CHAPTER-1 INTRODUCTION 1

CHAPTER-1
INTRODUCTION
1. INTRODUCTION
Metal inert gas/metal active gas (MIG/MAG) welding is an arc welding process, the melting takes place by Joule effect and a continuous electric arc, where the additional metal is supplied by a roll of wire. The weld is made by falling successive drops on the weld puddle. Argon gas (MIG welding) or active gas, CO2 (MAG welding) are used as plasma for providing protective atmosphere for the weld metal, so that contamination between oxygen and nitrogen is avoided. Electric energy is supplied from the welding generator for melting between wire and work piece to weld. According to two different control modes the arc mode, where voltage supplied from the generator is controlled to reach a point chosen by the welder the short-circuit mode, where current flows at pre-defined law, in gas metal arc welding the molten metal drop detachment form an electrode have complex interactions between different physical phenomena. Some of the researchers have studied the electromagnetic effects and some studied the thermal effects and the fluid dynamics. It is an arc welding process where heat is generated for arc between the workpiece and a consumable electrode. A bare solid wire called electrode is continuously fed to the weld zone, it becomes filler metal as it is consumed. Gas metal-arc welding overcomes the restrictions of using electrode of limited length and overcomes the inability to weld in various positions, which is a limitation of submerged-arc welding. In gas metal arc welding, the variations of power supplies, shielding gases and electrodes have significant effects, resulting in different process variations. All important metals used in different commercial applications such as aluminum, copper, stainless steel and carbon steel can be joined by this MIG welding process by choosing appropriate electrode, shielding gas and different welding conditions. It has been very important to know the performance of a welding process over a wide range of input process parameters. MIG welding is such a welding process which is extensively used in the industries for its high precision and accuracy capability. But performance of the welding depends largely upon the parameters like voltage, current and also on type of work-piece materials, electrode material combinations. A large amount of research works have been noticed to find out the most suitable combination of input process parameters for a desired output. In our present study workpiece of mild steel material of grade High Carbon High Chromium steel has been used tolerances.

1.1 GAS METAL ARC WELDING PROCESS
Gas metal arc welding (GMAW) is the most widely used fusion welding process in industries. It has extensive application, particularly, in the automotive industry. For vehicle chases, load and suspension applications, GMAW provides high joint efficiency in volume production and light weight designs by welding thin plates of high strength steels with various thicknesses to create complex assemblies (Long et al. 2009). GMAW is an important component in many industrial operations (ErdalKaradeniz et al 2005). It is easily found in any industry whose products require metal joining in a large scale (Correia et al 2004). It establishes an electric arc between a continuous filler material electrode and weld pool, with shielding from an externally supplied gas, which may be an inert gas, an active gas or a mixture. The heat of the arc melts the surface of the base metal and the end of the electrode. Molten metal from the electrode is transferred through the arc to the work where it becomes the deposited weld metal (weld bead).

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1.2 IMPORTANT ISSUES IN ARC WELDING
In spite of the fact that arc welding is the most preferred joining process in all manufacturing sectors, it is not free from serious setbacks like residual stresses and distortions in weldments. Due to the highly localized transient heat input, considerable welding residual stresses and deformations (welding distortion, welding shrinkage, welding war page) occur during and after welding. Since arc welding process involves highly complex thermal cycles, it gives rise to incompatible strains which result in the evolution of residual stresses and distortion in the weldments. The presence of the residual stresses in the weldments seriously affects the welded structures, as it prevents the application of full designed loads to the welded structures during their service. Distortions and residual stresses resulting from welding represent significant problems in the accurate fabrication of large structures. Welding residual stresses may cause brittle fractures in the finished structure. High magnitude residual stress fields are problematic in a fatigue loaded context and may induce buckling behavior. These problems increase as material thickness is reduced and joint frequency is increased, in order to optimize the stiffness-to-weight ratio of welded structures. The tensile residual stresses which often exist in the weld zone induce the further opening up of cracks. Furthermore, these tensile residual stresses reduce the fatigue strength and corrosion resistance but the compressive residual stresses reduce the buckling strength of the welded structures. Whereas the effect of the residual stresses is the most severe in affecting the integrity of the welded joints, distortion becomes more pronounced in the overall structure, particularly in the case of joining very thin materials. Welding induced distortion not only degrades the performance but also increases the cost of a fabricated structure.
1.3 CHARACTERISTIC OF MIG WELDING:
Uses a consumable wire electrode during the welding process that is fed from a spool.
Provides a uniform weld bead.
Produces a slag-free weld bead.
Uses a shielding gas, usually – argon, argon – 1 to 5% oxygen, argon – 3 to 25% CO2 and a combination argon/helium gas.
Is considered a semi-automatic welding process.
Allows welding in all positions.
Requires less operator skill than TIG welding.
Allows long welds to be made without starts or stops.
Needs little cleanup.
1.4 BACK GROUND
Several kinds of methods and techniques are being used to increase the productivity of welding. The improvement of better, highly efficient and economical processes has always been targeted in the research work carried out in the industries and at the research institutes. Development of metal transfer is just one of the distinguishing features of a new technology for automated and robotassisted applications. Besides welding, the new technologies are also suitable for use in welding of sheet metal. The workpiece to be joined and all their weld zones remain ‘colder’ than they would do in conventional gas metal arc welding. The reduced thermal input leads to advantages such as low distortion and higher precision. Other significant benefits for users include the higher quality of the welded joints, freedom from spatters, the ability to weld light-gauge sheet and the capability of joining both galvanized sheets and steel to aluminum. The concept of GMAW was first introduced in the early 1900s and it was only in 1948 that it was made commercially accessible. At the outset it was considered to be a high current density, small diameter, bare metal electrode process using an inert gas for arc shielding. As a consequence, the word MAG was used and it is frequently used. Preceding process developments integrated operation at low-current and pulse direct current, application to a wide variety of materials, and the use of reactive gases (particularly CO2) and some mixtures of other inert gases. Other expansion has led to the formal acceptance of the expression GMAW for the process since MIG and MAG are used. A variety of GMAW uses metal core electrode which necessitate a gas shield to protect the molten weld pool from atmospheric contamination. This process can be operated in semiautomatic machine or automatic mode, and different commercial metal such as carbon steel, highstrength low alloy steel, stainless steel, aluminum etc can be welded in all location by choosing a suitable shielding gas, electrode, and welding variables. Until now: ‘spatter-free’ arc welding has been somewhat wishful thinking, the unavailability of up to the mark power sources created many hindrances in putting this method into application at the industrial level. It is only a few years back, since the modern electrode controlled power sources have been developed.

1.5. NORMAL MIG METHOD
In MIG/MAG welding method, an arc is established between a continuous fed filler ire(consumable) electrode and the work piece. The electrode is fed automatically from the machine, through a liner, then out of a contact tip in the MIG/MAG gun. The weld metal is protected from the atmosphere by a flow of an inert gas, or gas mixture. The contact tip is hot or electrically charged, when the trigger is pulled and melts the wire for the weld puddle (figure1). After proper settings are made by the operator, the arc length is maintained at the set value, despite the reasonable changes that would be expected in the gun-to-work distance during normal operation. This automatic arc regulation is achieved in one of the two ways. The most common method is to utilize a constant-speed (but adjustable) electrode feed unit with a variable-current (constant-voltage) power source. Welding currents of 50 amperes up to more than 600 amperes are commonly used at welding voltages of 15V to 32V 6. As the gun-to-work relationship changes, which instantaneously alters the arc length, the power source delivers either more current (if the arc length is decreased) or less current (if the arc length is increased). This change in current will cause an equivalent change in the electrode melt-off rate, thus maintaining the desired arc length. The second method of arc regulation utilizes a constant-current power source and a variable-speed, voltagesensing electrode feeder. In this case, as the arc length changes, there is a corresponding change in the voltage across the arc. As this voltage change is detected, the speed of the electrode feed unit will change to provide either more or less electrode per unit of the time. This method of regulation is usually limited to larger electrodes with lower feed speeds. The characteristics of the GMAW process are best described by reviewing the three basic means by which metal is transferred from the electrode to the work: short-circuiting transfer, globular transfer, or spray transfer. The type of transfer is determined by a number of factors, the most influential of which are:

Figure 1.3 Typical process connection

•Magnitude and type the of welding current
•Electrode diameter
•Electrode composition
•Electrode extension beyond the contact tip of tube
•Composition of shielding gas
•Power supply output.
In short-circuit welding, small droplets of molten wire, heated when shortcircuited, flow together to make a puddle as they touch the base metal. The inert gas flows out of the gun cools and keeps the weld puddle shielded from the atmosphere. 7, 8Short circuit gas metal arc welding is characterized by regular contact between the electrode and the weld pool. Droplet growth occurs in the arcing period, whereas, during the contact period, metal transfer from the electrode to the work piece takes place. The cyclic behavior of the process can be described in terms of the short circuit time, the arc time or the short circuit frequency. As the arc does not burn during the short circuit period, the overall heat input is low compared to open arc welding. Therefore, GMAW-S always results in a small, fast-freezing weld pool, and, therefore, the process is especially suited for joining thin sections, for out-of-position welding and for bridging root openings.

1.6 WELDING ENERGY AND HEAT INPUT
In GMAW a sufficient amount of power (energy transferred per unit time) and energy density is applied to the electrode and this cause melting. Heat input is a relative measure of the energy transferred per unit length of weld. It is an important characteristic because it influences the cooling rate, which may affect the mechanical properties and metallurgical structure of the weld and the HAZ .Heat input is typically calculated as the ratio of the power (i.e., voltage x current) to the velocity of the heat source as follows:
Q = ?
1000V
60??
13
Q = Heat input (kJ/mm)
? =Welding voltage (volts)
I = welding current (amps) V = Travel speed (mm/min) ? = efficiency factor for GMAW is
0.8 14.
The above equation is useful for comparing different welding procedures for a given welding process. Heat input increases, the rate of cooling decreases for a given base metal thickness. These two variables interact with others such as material thickness; specify heat, density and thermal conductivity. The thermal diffusivity of the base material plays a large role in the HAZ, if the diffusivity is high, the material cooling rate is high and the HAZ is relatively small. Conversely, a low diffusivity leads to slower cooling and a larger HAZ.

1.7 WELDING MATERIALS
The GMAW process can be operated in semi-automatic and automatic modes. All commercially important metals, such as carbon steel, high-strength low-alloy steel, stainless steel, and aluminum, copper, and nickel alloys can be welded in all positions by this process if appropriate shielding gases, electrodes, and welding parameters are chosen.

1.8 APPLICATIONS
The MIG/MAG process proved itself highly useful for rationalized welding of unalloyed and low-alloy structural steels, today it can be best put to use for aluminum alloys, high quality structural steels, and stainless steel. This is due to the pulsed and dips transfer arcs techniques. Despite of the type of arc, MIG/MAG displays significant advantages over other welding processes. These include good deposition rate, deeper fusion penetration, simple handling and total mechanization, in addition to high productivity. With the arrival of programmed welding, gas-metal arc welding has become the predominant process choice. The process of MIG/MAG is getting wider applications in the areas of high-production and automated applications i.e. ship building industry, pipelines, tack welding, pressure vessels, gas cylinders welding and maintenance repairs.

1.9 SCOPE OF THE PROJECT
The main objective of the project is during welding process we have to get the minimum changes in the physical properties and no metallurgical defect is present. Defect free welding process should be made. To achieve a good weldment we will be working with many samples and quality checks with destructive and non destructive testing in this experimental work .

CHAPTER-2
LITREATURE REVIEW
Izzatul Aini Ibrahim1,1 et.al were analyzed GMAW process is leading in the development in arc welding process which is higher productivity and good in quality. They were studied, the effects of different parameters on welding penetration, microstructural and hardness measurement in mild steel that having the 6mm thickness of base metal by using the robotic gas metal arc welding are investigated. The variables that choose in this study are arc voltage, welding current and welding speed. The arc voltage and welding current were chosen as 22, 26 and 30 V and 90, 150 and 210 A respectively. The welding speed was chosen as 20, 40 and 60 cm/min. The penetration, microstructure and hardness were measured for each specimen after the welding process and the effect of it was studied. As a result, it obvious that increasing the parameters value of welding current increased the value of depth of penetration. Other than that, arc voltage and welding speed is another factor that influenced the value of depth of penetration. The microstructure shown the different grain boundaries of each parameters that affected of the welding parameters.
D.S. Yawas,2 et.al were investigated fatigue behavior of welded austenitic stainless steel in 0.5 M hydrochloric acid and wet steam corrosive media has been investigated. The immersion time in the corrosive media was 30 days to simulate the effect on stainless steel structures/equipment in offshore and food processing applications and thereafter annealing heat treatment was carried out on the samples. The findings from the fatigue tests show that seawater specimens have a lower fatigue stress of 0.5 _ 10_5 N/mm2 for the heat treated sample and 0.1 _ 10_5 N/mm2 for the unheat-treated sample compared to the corresponding hydrochloric acid and steam samples. The post-welding heat treatment was found to increase the mechanical properties of the austenitic stainless steel especially tensile strength but it reduces the transformation and thermal stresses of the samples. These findings were further corroborated by the microstructural examination of the stainless steel specimen.

M.N.Chougule3 et.al were carried out Gas metal arc welding (GMAW) controls the metal from the wire rod by developing the arc as well as by controlling the input process parameters. High heating at a one location during welding and further rapid cooling generates residual stress and distortion in the weld and base metal. In the last few decades, various research efforts have been directed towards the control of welding process parameter aiming at reducing residual stress and distortion they are strongly affected by many parameters like structural, material and welding parameters. Such welding failure can be minimized by controlling the weld heat input. The distribution of the temperature in weld joint of AISI202 grade high strength steel is investigated by Finite Element Method (FEM) using ANSYS software and experiment has been performed to verify the developed thermomechanical finite element model using the GMAW process. Basic aim of our paper is to analyse temperature distribution and residual stresses in dissimilar metal welded plates to avoid future failure in material because experimental process is costly. The behavior of weld zone is affected by variation in temperature distribution, microstructure and mechanical properties of the material. The residual stress gradient near the fusion zone is higher than in any other location in the surrounding area. Because of this stress gradient, cold crack at the fusion zone in high strength steel occur. The main objective of this simulation is the determination of temperatures and stresses during and after the process. Temperature distributions define the heat affected zone (HAZ) where material properties are affected. Stress calculation is necessary because high residual stresses may be caused fractures, fatigue which causes unpredictable failures in regions near the weld bead region.
LI YAJIANG4 et.al were experimentally analyzed distribution of the residual stress in the weld joint of HQ130 grade high strength steel was investigated by means of finite element method (FEM) using ANSYS software. Welding was carried out using gas shielded arc welding with a heat input of 16 kJ/cm. The FEM analysis on the weld joint reveals that there is a stress gradient around the fusion zone of weld joint. The instantaneous residual stress on the weld surface goes up to 800 ~ 1000 MPa and it is 500 ~ 600 MPa, below the weld. The stress gradient near the fusion zone is higher than any other location in the surrounding area. This is attributed as one of the significant reasons for the development of cold cracks at the fusion zone in the high strength steel. In order to avoid such welding cracks, the thermal stress in the weld joint has to be minimized by controlling the weld heat input.
Q.Wang5 et.al were carried out influences of parameters of tungsten inert gas arc welding on the morphology, microstructure, tensile property and fracture of welded joints of Ni-base superalloy have been studied. Results show that the increase of welding current and the decrease of welding speed bring about the large amount of heat input in the welding pool and the enlargement of width and deepness of the welding pool. The increase of impulse frequency has the same effect on the microstructure compared with the increase of welding current. The effect of welding parameters on the tensile strength and fracture was analyzed. It is found that the root of welding joint is unwelded when the welding current is lower, so that the strength and elongation of welded joint are inferior. And the more welding defects in the welding zone and the more hard and brittle phase precipitates in the overheated zone when the welding current is too high. Consequently, the strength and plasticity go up first and then go down, i.e. they have a peak value with welding current increasing. In addition, the decrease of impulse frequency is beneficial to the strength of the welded joint.
G. Magudeeswaran6 were studied activated TIG (ATIG) welding process mainly focuses on increasing the depth of penetration and the reduction in the width of weld bead has not been paid much attention. The shape of a weld in terms of its width-to-depth ratio known as aspect ratio has a marked influence on its solidification cracking tendency. The major influencing ATIG welding parameters, such as electrode gap, travel speed, current and voltage, that aid in controlling the aspect ratio of DSS joints, must be optimized to obtain desirable aspect ratio for DSS joints. Hence in this study, the above parameters of ATIG welding for aspect ratio of ASTM/UNS S32205 DSS welds are optimized by using Taguchi orthogonal array (OA) experimental design and other statistical tools such as Analysis of Variance (ANOVA) and Pooled ANOVA techniques. The optimum process parameters are found to be 1 mm electrode gap, 130 mm/min travel speed, 140 A current and 12 V voltage. The aspect ratio and the ferrite content for the DSS joints fabricated using the optimized ATIG parameters are found to be well within the acceptable range and there is no macroscopically evident solidification cracking
Fanrong Kong7 et.al were investigated a model based on a double-ellipsoidal volume heat source to simulate the gas metal arc welding (GMAW) heat input and a cylindrical volume heat source to simulate the laser beam heat input was developed to predict the temperature field and thermally induced residual stress in the hybrid laser–gas metal arc (GMA) welding process. Numerical simulation shows that higher residual stress is distributed in the weld bead and surrounding heat-affected zone (HAZ). Effects of the welding speed on the isotherms and residual stress of the welded joint are also studied. It is found that an increase in welding speed can reduce the residual stress concentration in the as-weld specimen. A series of experiments has been performed to verify the developed thermo-mechanical finite element model (FEM), and a qualitative agreement of residual stress distribution and weld geometrical size is shown to exist.
N. Akku?18 et.al were studied is to realize a simulation of arc welding using Finite Elements Analysis (FEA). In general, thin steel metals are used in the automotive and machine industries and the distortion after arc welding is more evident, because of the lack of quality in the product this creates problems. It is important to predetermine these problems before welding process. One way of the prediction of welding process is “try and see”. But this may need high cost and time. Therefore, Finite Element Method is very often used today to monitor and predict the welding process. In order to do this, MSC.Marc-Mentat program was used to simulate the arc welding process by 3-D modeling in terms of temperature distribution and distortions. Then, the results of experiments were compared to that of obtained in the simulation. The comparison of the results revealed familiarity between the presented FE model and experiments
J. Dutta9 et .al were investigated reveals an elaborate analysis of variation of thermal properties of high carbon steel plate butt joints formed by DC Gas Tungsten Arc (GTA) welding. Experiment has conducted to predict the two dimensional temperature cycle developed. To find out the heat flux distribution, Gaussian Heat source model has been implemented. Carslaw-Jaeger’s mathematical model has been incorporated to estimate the variation of thermal conductivity. To portray the change in specific heat at different locations from the fusion boundary at experimental temperatures, Thin plate model has been utilized. Heat loss due to convection, radiation and evaporation have been studied. To estimate total heat loss from weld joint at different locations a method has been proposed and Vinokurov’ s empirical correlation has been used for validation. At very close region (36mm from fusion boundary) to heat affected zone all thermal properties have shown significant variation based on experimental results. From the analysis of heat loss an optimum temperature has been observed and it is helpful to define the range of convection and radiation heat loss phenomena.
R. Ahmad 10 et.al were studied the effect of a post-weld heat treatment (PWHT) on the mechanical and microstructure properties of an AA6061 sample welded using the gas metal arc welding (GMAW) cold metal transfer (CMT) method. The CMT method was used because the method provides spatter-free welding, outstanding gap bridging properties, low heat input and a high degree of process flexibility. The welded samples were divided into as-welded and PWHT samples. The PWHTs used on the samples were solution heat treatment, water quenching and artificial aging. Both welded samples were cut according to the ASTM E8M-04 standard to obtain the tensile strength and the elongation of the joints. The failure pattern of the tensile tested specimens was analysed using scanning electron microscopy (SEM). A Vickers microhardness testing machine was used to measure the hardness across the joints. From the results, the PWHTs were able to enhance the mechanical properties and microstructure characteristics of the AA6061 joints welded by the GMAW CMT method.

CHAPTER –3
WELDING PROBLEM ON PRESSURE VESSEL STEEL
3.1 PROBLEM IDENTIFICATION
In many cases the welder needs only to know the techniques of actual welding and does not need to be concerned about the type or grade of steel being welded. This is because a large amount of steel used in fabricating a metal structure is low Carbon or plain carbon steel (also called mild steel). When welding these steels with any of the common arc welding processes like Stick Mig or Tig there are generally few precautions necessary to prevent changing the properties of the steel.
Steels that have higher amounts of Carbon or other alloys added may require special procedures such as preheating and slow cooling, to prevent cracking or changing the strength characteristics of the steel. The welder may be involved in following a specific welding procedure to ensure weld metal and base metal has the desired strength characteristics.
3.2 THE EFFECT OF WELDING ON CARBON STEEL
? Steel is an alloy, or metallic mixture, containing primarily iron. A variety of other metals, such as carbon, are used to promote certain properties in the alloy. Carbon has a strengthening effect when added to iron.
3.2.1Carbon Rating
? There are different types of steel available, including several varieties of carbon steel. Low-carbon steel contains a maximum concentration
of 0.3 percent carbon, while high-carbon steel contains a maximum concentration of 1 percent carbon.
3.2.2 Carbon in Steel
? Carbon strengthens steel, but also reduces its ductility, or pliability. The low ductility of high-carbon steel makes it more difficult to weld.
3.2.3 Effects of Welding on High-Carbon Steel
? When welding high-carbon steel, a high concentration of martensite may form in the weld. Martensite makes the metal extremely brittle, causing a weak weld that may break as soon as it cools.
3.2.4 Welding High-Carbon Steel
According to ESAB Welding and Cutting, Inc., a low hydrogen electrode must be used when welding high-carbon steels. Additionally, annealing, or heating, the metal prior to welding slows the cooling process and prevents the concentration of martensite. Post heating will also reduce stress and strengthen the weld.
3.3 WELDING EFFECTS:
In the correct sense of the word, a defect is a rejectable discontinuity or a flaw of rejectable nature. Certain flaws acceptable in one type of product. A defect is definitely a discontinuity, but a discontinuity need not necessarily be a defect. Acceptance or rejection of flaws is based on different factors and to mention a vital few are:
Stresses to which the parts will be subjected during service.
Type of material used.
The temperature and pressure to which the parts will be stressed.
Its thickness.
The environment (corrosive or non-corrosive).
Safety.
Consequences of failure.
Cost and accessibility for repair, etc
Acceptance standards dictate the type of inspection and testing the weld is subjected to before giving a judgment. The quality control in charge shall analyse whether the flaws are inherent because of the process or are due to the processing or service conditions. It is of immense importance to see that the base material used for fabrication shall be of good quality and attested materials are demanded in the manufacture of space vehicles and ships, submarines, pressure vessels, power boiler components, heavy duty cranes, structures, bridges, etc, wherein the failure of weld will lead to loss of life, money and reputation.
The weld defects can be broadly classified into two types. They are:
Planar defects/ two dimensional defects.
Voluminar defects / three dimensional defects.
Planar defects such as crack, lack of fusion, lack of penetration, severe undercut are critical in nature and involve lack of bonding and are not tolerated to any exent. Voluminar defects such as slag inclusion, cavities, pores ,etc are tolerated to a certain extent depending on the product class. Geometric defect such as excess reinforcement, under fill or under flush, root concavity are also permitted to a certain extent. If they from sharp notches, they are smoothened out wherever accessible to avoid stress concentration.
3.4 GENERAL REASONS FOR DEFECTS
The importance of weld quality is increasingly felt as we go ahead with the fabrication of sophisticated products using higher strength materials combined with critical design consideration. However, defects are likely to be present in materials produced at economic cost. Defects are generally introduced because of:
Lack of know how and experience.
Welding process characteristics.
Base metal composition.
Defective welding filler metals.
Joint design.
Welding environment (wind, fit up, temperature, etc.)

3.5 TYPE OF DEFECTS AND THEIR SIGNIFICANCE
Defects in weldments in general can be classified as follows:

3.5.1 Defects Involving Inadequate Bonding
Lack of fusion
Incomplete penetration

3.5 2 Foreign Inclusions
Slag
Oxide films
Tungsten

3.5.3 Geometric Defects
Undercut
Excessive reinforcement
Burn through or excessive penetration
Distortion
Improper weld profile

3.5.4 Metallurgical defects
Cracks
Gas porosity
Arc strikes
Embrittlement
Structural notches

3.6 METALLURGICAL DEFECTS
CRACKS:
Cracks are the linear ruptures of the metal under stress. Sometimes they appear large and frequently they are narrow separations. The major classification of cracks is:
Hot cracking
Cold cracking
Micro fissuring
Base metal cracking
Crater cracking.

3.6.1 Reason For Cracking
Base metal composition
Welding process characteristics
Defective welding filler materials
Welding environment
Joint design
Cracking may occur in:
i) Weld metal ii) Heat affected zone

3.6.2 Hot Cracking:
Hot cracking occurs at elevated temperature during cooling and solidifying from the molten stage. The main causes are the restraint on the joint and the presence of higher carbon and sulphur. The other reason is segregation of weld metal due to bead shape. Hot cracks are inter-granular. To avoid hot cracks, it is essential to keep these joints with least restraint and to have least amount of heat input. Proper matching of electrodes and cooling rate will reduce the probabilities of cracking. The cracks on the craters of weld metal are examples for hot cracking.
MPI or LPI are used to detect surface cracks while ultrasonic testing is suitable for internal cracks.

3.6.3 Cold Cracking:
Cold cracking in steels refers to cracking which occurs even after a few days. In general, cold cracking starts in the Heat Affected Zone (HAZ) of the weld metal. It is primarily associated with combined effects of hydrogen, restraint and martensite formation. Increasing the carbon content in the base metal and the manganese content in the weld metal also prompts cold cracking. To minimize cracking it is essential to use low hydrogen electrodes and pre heating. Usually MPI for ferrous materials and LPI for non ferrous materials are used to detect these cracks at surface.

CHAPTER-4
SELECTION OF MATERIAL
4.7.1CHEMICAL PROPERTIES
Table 4.1 Chemical properties
Element Content (%)
Iron, Fe 60
Chromium, Cr 23
Nickel, Ni 14
Manganese, Mn 2
Silicon, Si 1
Carbon, C 0.20
Phosphorous, P 0.045
Sulfur, S 0.030

4.7.2 PHYSICAL PROP ERTIES
Table 4.2 Physical properties
Properties Metric Imperial
Density 8 g/cm3 0.289 lb/in³
Melting point 1455°C 2650°F

4.7.3 APPLICATION
Grade 309 stainless steel is used in the following applications:
Boiler baffles
Furnace components
Oven linings
Fire box sheets
Other high temperature containers.
CHAPTER-5
EXPERIMENTAL DESIGN
5.1 TAGUCHI INTRODUCTION
Basically, experimental design methods were developed original fisher. However experimental design methods are too complex and not easy to use. Furthermore, a large number of experiments have to be carried out when the number of the process parameters increases, to solve this problem, the Taguchi method uses a special design of orthogonal arrays to study the entire parameter space with a small number of experiments only. The experimental results are then transformed into a signal– to – noise (S/N) ratio to measure the quality characteristics deviating from the desired values Usually, there are three categories of quality characteristics in the analysis of the S/N ratio, i.e., the–lower–better, the–higher–better, and the–nominal–better. The S/N ratio for each level of process parameter is compared based on the S/N analysis. Regardless of the category of the quality characteristic, a greater S/N ratio corresponds to better quality characteristics.
Therefore, the optimal level of the process parameters is the level with the greatest S/N ratio Furthermore, a statistically significant with the S/N and ANOVA analyses, the optimal combination of the process parameters can be predicted. Finally, a confirmation experiment is conducted to verify the optimal process parameters obtained from the parameter design.There are 3Signal-toNoise ratios of common interest for optimization of Static Problems. The formulae for signal to noise ratio are designed so that an experimenter can always select the largest factor level setting to optimize the quality characteristic of an experiment. Therefore a method of calculating the Signal-To-Noise ratio we had gone for quality characteristic. They are

Smaller-The-Better,
Larger-The-Better, 3. Nominal is Best.
SMALLER IS BETTER
The signal-to-noise (S/N) ratio is calculated for each factor level combination. The formula for the smaller-is-better S/N ratio using base 10 log is:
S/N = -10*log(S (Y2)/n)
Where Y = responses for the given factor level combination and n = number of responses in the factor level combination.

LARGER IS BETTER
The signal-to-noise (S/N) ratio is calculated for each factor level combination. The formula for the larger-is-better S/N ratio using base 10 log is:
S/N = -10*log(S(1/Y2)/n)
Where Y = responses for the given factor level combination and n = number of responses in the factor level combination.

NOMINAL IS BEST
The signal-to-noise (S/N) ratio is calculated for each factor level combination. The formula for the nominal-is-best I S/N ratio using base 10 log is:
S/N = -10*log (s2)
Where s = standard deviation of the responses for all noise factors for the given factor level combination

5.2 DESIGN OF EXPERIMENT
Table 5.1 Process parameters and their levels
Levels Process parameters AMPS VOLT BEVEL?
1 140 18 55
2 160 20 65
3 180 22 70

MINITAB-16 SOFTWARE

Figure 5.1 Minitab software

5.3 DESIGN OF ORTHOGONAL ARRAY
First Taguchi Orthogonal array is designed in minitab-16 to calculate S/N ratio and means which steps is given below.Create Taguchi Design is selected as shown in figure. Then a window of Taguchi design is opened.To start Minitab, click shortcut of Minitab on Desktop of computer. A window is opened in computer as shown in Figure,

Figure 5.2 Create Taguchi Design

5.4 AN ORTHOGONAL ARRAY L9 FORMATION (INTERACTION)
AMPS VOLT BEVEL?
140 18 55
140 20 65
140 22 70
160 18 65
160 20 70
160 22 55
180 18 70
180 20 55
180 22 65
CHAPTER 6DESTRUCTIVE AND NON DESTRUCTIVE TESTS
6.1 INTRODUCTION OF HARDNESS
There are three types of tests used with accuracy by the metals industry; they are the Brinell hardness test, the Rockwell hardness test, and the Vickers hardness test. Since the definitions of metallurgic ultimate strength and hardness are rather similar, it can generally be assumed that a strong metal is also a hard metal. The way the three of these hardness tests measure a metal’s hardness is to determine the metal’s resistance to the penetration of a non-deformable ball or cone. The tests determine the depth which such a ball or cone will sink into the metal, under a given load, within a specific period of time. The followings are the most common hardness test methods used in today`s technology:
6.1.1 ROCKWELL HARDNESS TEST
Rockwell Hardness systems use a direct readout machine determining the hardness number based upon the depth of penetration of either a diamond point or a steel ball. Deep penetration indicated a material having a low Rockwell Hardness number.
However, a low penetration indicates a material having a high Rockwell Hardness number. The Rockwell Hardness number is based upon the difference in the depth to which a penetrator is driven by a definite light or “minor” load and a definite heavy or “Major” load.
The ball penetrators are chucks that are made to hold 1/16″ or 1/8″ diameter hardened steel balls. Also available are ¼” and ½” ball penetrators for the testing of softer materials.
There are two types of anvils that are used on the Rockwell hardness testers. The flat faceplate models are used for flat specimens. The “V” type anvils hold round specimens firmly.
Test blocks or calibration blocks are flat steel or brass blocks, which have been tested and marked with the scale and Rockwell number. They should be used to check the accuracy and calibration of the tester frequently.
Using the “C” Scale;
Use a Diamond indenter
Major load: 150 Kg, Minor load: 10 Kg
Use for Case hardened steel titanium, tool steel.
Do not use on hardened steel
6.1 HARDNESS VALUE IN HRB
SAMPLES S1 S2 S3 S4 S5 S6 S7 S8 S9
SS309 80 73 82 89 82 84 90 86 95

6.2 IMPACT TEST
Izod impact strength testing is an ASTM standard method of determining impact strength. A notched sample is generally used to determine impact strength. Impact is a very important phenomenon in governing the life of a structure. In the case of aircraft, impact can take place by the bird hitting the plane while it is cruising, during take – off and landing there is impact by the debris present on the runwayAn arm held at a specific height (constant potential energy) is released. The arm hits the sample and breaks it. From the energy absorbed by the sample, its impact strength is determined.The North American standard for Izod Impact testing is ASTM D256. The results are expressed in energy lost per unit of thickness (such as ft-lb/in or J/cm) at the notch. Alternatively, the results may be reported as energy lost per unit cross-sectional area at the notch (J/m² or ft-lb/in²). In Europe, ISO 180 methods are used and results are based only on the cross-sectional area at the notch (J/m²).The dimensions of a standard specimen for ASTM D256 are 4 x 12.7 x 3.2 mm (2.5″ x 0.5″ x 1/8″). The most common specimen thickness is 3.2 mm (0.125″), but the width can vary between 3.0 and 12.7 mm (0.118″ and 0.500″).The Izod impact test differs from the Charpy impact test in that the sample is held in a cantilevered beam configuration as opposed to a three point bending configuration.
6.2.1 IMPACT STRENGTH
In our Project Impact Strength determined through impact testing machine by charpy method.
Specification of the machine and Size of the specimen
EnergyRange = 0 – 300 J
Least Count (1 Division) = 2J
Specimen size = 10 X 10 X 55 mm
Notch = V NOTCH
Notch Depth = 2mm

Table 6.2 Impact strength
Materials TEST PLATE Average in joules
SS309 S1 20
S2 20
S3 37
S4 14
S5 19
S6 17
S7 16
S8 11
S9 17

6.2.2 EXPERIMENTAL DATA
Table 6.2 S/N ratios values for the Impact strength
T.NO Designation AMPS VOLT BEVEL IMPACT SNRAT
1 A1B1C1 140 18 55 20 26.0206
2 A1B2C2 140 20 65 20 26.0206
3 A1B3C3 140 22 70 37 31.3640
4 A2B1C2 160 18 65 14 22.9226
5 A2B2C3 160 20 70 19 25.5751
6 A2B3C1 160 22 55 17 24.6090
7 A3B1C3 180 18 70 16 24.0824
8 A3B2C1 180 20 55 11 20.8279
9 A3B3C2 180 22 65 17 24.6090
Figure-6.1 specimen

NON-DESTRUCTIVE TESTING
6.3 ULTRASONIC TESTING
Non-destructive Test and Evaluation is aimed at extracting information on the physical, chemical, mechanical or metallurgical state of materials or structures. This information is obtained through a process of interaction between the information generating device and the object under test. The information can be generated using X-rays, gamma rays, neutrons, ultrasonic methods, magnetic and electromagnetic methods, or any other established physical phenomenon.The process of interaction does not damage the test object or impair its intended utility value. The process is influenced by the physical, chemical and mechanical.NDT Methods range from the simple to the intricate. Visual inspection is the simplest of all. Surface imperfections invisible to they may be revealed by penetrate or magnetic methods. If serious surface defects are found, there is often little point in proceeding further to the more complicated examination of the interior by other methods like ultrasonic or radiography.The principal NDT methods are Visual or optical inspection, Dye penetrant testing, Magnetic article testing, Radiography testing and Ultrasonic testing.
ASNT – American Society for Nondestructive Testing
ISNT – International Society for Nondestructive Testing
CWI – Certified Welding Inspector
NDT – Non Destructive testing
NDE – Non Destructive Evaluation
NDI – Non Destructive Inspection
Level –I work under the supervision.
Level-II Calibrate, Test, Interpret and evaluate with respect to code and standard.
Level –III Establish techniques and procedure for specific process
6.3.1 TYPES OF NDT:
Visual Testing- Ultraviolet. Infrared and visible light
Penetrate testing
Electromagnetic testing
Magnetic particle Testing
Acoustic Emissions
Ultrasonic testing
Radiography (RT) – X rays , Gamma rays & Beta particles
6.3.2 ULTRASONIC TESTING
Ultrasonic testing (UT) is a family of non-destructive testing techniques based on the propagation ofultrasonic waves in the object or material tested. In most common UT applications, very short ultrasonic pulse-waves with center frequencies ranging from 0.1-15 MHz, and occasionally up to 50 MHz, are transmitted into materials to detect internal flaws or to characterize materials. A common example is ultrasonic thickness measurement, which tests the thickness of the test object, for example, to monitor pipework corrosion.Ultrasonic testing is often performed on steel and other metals and alloys, though it can also be used onconcrete, wood and composites, albeit with less resolution. It is used in many industries including steel and aluminium construction, metallurgy, manufacturing, aerospace, automotive and other transportation sectors.Concrete Ultrasonic inspection is a nondestructive method in which beams of high frequency sound waves are introduced into materials for the detection of subsurface flaws in the material. The sound waves travel through the material with some attendant loss of energy and are reflected at interfaces (cracks or flaws). The reflected beam is displayed and then analyzed to define the presence and location of flaws or discontinuities.Ultrasonic testing is used to find out the size and location of the defects. The most commonly used ultrasonic testing technique is pulse echo, wherein sound is introduced into a test object and reflections are returned to a receiver from internal imperfections or from the parts geometrical surfaces.
6.3.3APPLICATION OF NDT
Nuclear, space, aircraft, defense, automobile, chemical and fertilizer industries.
Heat exchanger, Pressure vessels, electronic products and computer parts.
High reliable structures and thickness measurement.
6.3.3.1 SPECIFICATION
UT instrument : PX 20
Transducer angle : 45o
Technique : pulse Echo
Size : 100mm x 100mm
Material : SS309
Range : 100mm

UT TEST EQUIPMENTS:

Figure – 6.2 ultrasonic CRT screen
TABLE 6.4: APPLICATION WAVES
Testing Method Typical Applications
Shear waves Inspection of welds, plates, pipes, tubing and complex geometry of forging and castings
Surface waves Inspection of surface defects
Plate Waves Detection of laminations in thin materials, lack of bonding in composite materials

Figure-6.3 ultrasonic test equipment
6.3.4 ULTRASONIC RESULT
TABLE 6.5: ULTRASONIC TEST REPORT
S.NO ITEM NO /
LOCATION MATERIAL
Components THICKNESS INDICATIO
NS RESULT
1. TP-1 SS309 10MM – ACCEPT
2. TP-2 – ACCEPT
3. TP-3 ICP &Por REJECT
4. TP-4 – ACCEPT
5. TP-5 – ACCEPT
6. TP-6 – ACCEPT
7. TP-6 – ACCEPT
8. TP-6 Cr REJECT
9 TP-9 – REJECT

6.3.4.1LEGENDS:
NI –No Indications Cr – crack
Inc – Inclusion EP – Excess penetration
SI – Slag U/C – Undercut
Por – Porosity Con – Concavity
Lam – Lamination Lof – Lack of fusion
Lop – Lack of penetration ICP – Incomplete penetration
6.4 MICROSCOPE IMAGE ANALYSER
Microscope image processing is a broad term that covers the use digital image processing of  techniques to process, analyze and present images obtained from a microscope . Such processing is now commonplace in a number of diverse fields such as medicine, biological research, cancer research, drug testing, metallurgy, etc. A number of manufacturers of microscopes now specifically design in features that allow the microscopes to interface to an image processing system.

Software Used:METALPLUS
6.4.1 specifications:-
Objective lens :5X,10X,20X,50X
Eye piece :10X
Magnification range :50X-500X
Figure-6.3 specimen

6.4.1MICROSCOPIC ANALYSIS IMAGES

S1

S2

S3

S4

S5

S6

S7

S8

S9
CHAPTER 7
RESULTS AND DISCUSSION
7.1 MPACT STRENGTH FOR EACH LEVEL OF THE PROCESS
TABLE : 7.1.1 Response Table for Signal to Noise Ratios-Larger is better
Level AMPS VOLT BEVEL
1 27.80 24.34 23.82
2 24.37 24.14 24.52
3 23.17 26.86 27.01
Delta 4.63 2.72 3.19
Rank 1 3 2

TABLE: 7.1.2 Response Table for Means
Level AMPS VOLT BEVEL
1 25.67 16.67 16.00
2 16.67 16.67 17.00
3 14.67 23.67 24.00
Delta 11.00 7.00 8.00
Rank 1 3 2

TABLE: 7.1.3 Factor Information
Factor Type Levels Values
AMPS fixed 3 140,160,180
VOLT fixed 3 18,20,22
BEVEL fixed 3 55, 65, 70

TABLE:7.1.4 Analysis of Variance
Source DF Seq SS Adj SS F P % OF Contribution
AMPS 2 206.00 103.000 14.71 0.064 48
VOLT 2 98.00 49.000 7.00 0.125 23
BEVEL 2 114.00 57.000 8.14 0.109 26
Error 2 14.00 7.000 3
Total 8 732.00 100

Regression Equation
IMPACT = 19.000 + 6.67 AMPS_140 – 2.33 AMPS_160 – 4.33 AMPS_180 –
2.33 VOLT_18 – 2.33 VOLT_20 4.67 VOLT_22 – 3.00 BEVEL_55 –
2.00 BEVEL_65 + 5.00 BEVEL_70
GRAPH FOR SN RATIO
180
160
140
25.0
22.5
20.0
17.5
15.0
22
20
18
70
65
55
A
M
P
S
Mean of Means
V
O
L
T
B
E
V
E
L
Main Effects Plot for Means
Data Means

180
160
140
25.0
22.5
20.0
17.5
15.0
22
20
18
70
65
55
A
M
P
S
Mean of Means
V
O
L
T
B
E
V
E
L
Main Effects Plot for Means
Data Means

Fig: 7.1 Main effectsplot for SN Ratio
GRAPH FOR MEANS
180
160
140
28
27
26
25
24
23
22
20
18
70
65
55
A
M
P
S
Mean of SN ratios
V
O
L
T
B
E
V
E
L
Main Effects Plot for SN ratios
Data Means
Signal-to-noise: Larger is better

180
160
140
28
27
26
25
24
23
22
20
18
70
65
55
A
M
P
S
Mean of SN ratios
V
O
L
T
B
E
V
E
L
Main Effects Plot for SN ratios
Data Means
Signal-to-noise: Larger is better

Fig; 7.2 Main effectsplot for means

————— 4/9/2018 5:50:19 AM ————————————————————

Welcome to Minitab, press F1 for help.

Taguchi Analysis: IMPACT versus AMPS, VOLT, BEVEL

Response Table for Signal to Noise Ratios
Larger is better

Level AMPS VOLT BEVEL
27.80 24.34 23.82
24.37 24.14 24.52
23.17 26.86 27.01
Delta 4.63 2.72 3.19
Rank 1 3 2

Response Table for Means

Level AMPS VOLT BEVEL
25.67 16.67 16.00
16.67 16.67 17.00
14.67 23.67 24.00
Delta 11.00 7.00 8.00
Rank 1 3 2

General Linear Model: IMPACT versus AMPS, VOLT, BEVEL

Method

Factor coding (-1, 0, +1)

Factor Information

Factor Type Levels Values
AMPS Fixed 3 140, 160, 180
VOLT Fixed 3 18, 20, 22
BEVEL Fixed 3 55, 65, 70

Analysis of Variance

Source DF Adj SS Adj MS F-Value P-Value
AMPS 2 206.00 103.000 14.71 0.064
VOLT 2 98.00 49.000 7.00 0.125
BEVEL 2 114.00 57.000 8.14 0.109
Error 2 14.00 7.000
Total 8 432.00

Model Summary

S R-sq R-sq(adj) R-sq(pred) 2.64575 96.76% 87.04% 34.37%

Coefficients

Term Coef SE Coef T-Value P-Value VIF
Constant 19.000 0.882 21.54 0.002
AMPS
140 6.67 1.25 5.35 0.033 1.33
160 -2.33 1.25 -1.87 0.202 1.33 VOLT
18 -2.33 1.25 -1.87 0.202 1.33
20 -2.33 1.25 -1.87 0.202 1.33 BEVEL
55 -3.00 1.25 -2.41 0.138 1.33
65 -2.00 1.25 -1.60 0.250 1.33

Regression Equation

IMPACT = 19.000 + 6.67 AMPS_140 – 2.33 AMPS_160 – 4.33 AMPS_180 – 2.33 VOLT_18 2.33 VOLT_20
+ 4.67 VOLT_22 – 3.00 BEVEL_55 – 2.00 BEVEL_65 + 5.00 BEVEL_70
7.1.1 CONFORMATION OF TEST :-
Impact is larger-the-better type quality characteristic. Therefore higher values of hardness are considered to be optimal. It is clear from Graph that hardness of is highest atFirst level of Welding Current, third level of Welding Voltage and third level of Welding Bevel. Process parameters and their selected optimal levels are given below:
Welding Current A (1) 140 A
Welding Voltage B (3) 22 V
Welding bevel angle C (3) 70
7.2 HARDNESS TEST RESULT AND DISCUSION
Taguchi Analysis: HARDNESS versus AMPS, VOLT, BEVEL
TABLE : 7.2.1 Response Table for Signal to Noise Ratios-Larger is better
Level AMPS VOLT BEVEL
1 37.87 38.71 38.41
2 38.58 38.08 38.60
3 23.17 26.86 27.01
Delta 1.24 0.69 0.19
Rank 1 2 3

TABLE: 7.2.2 Response Table for Means
Level AMPS VOLT BEVEL
1 78.33 86.33 83.33
2 85.00 80.33 85.67
3 90.33 87.00 84.67
Delta 12.00 6.67 2.33
Rank 1 2 3

TABLE: 7.2.3 Factor Information
Factor Type Levels Values
AMPS fixed 3 140,160,180
VOLT fixed 3 18,20,22
BEVEL fixed 3 55, 65, 70

168846542989500GRAPH FOR SN RATIO
Fig: 7.3 Main effectsplot for SN Ratio
GRAPH FOR MEANS
1612265532765000

Fig: 7.3 Main effectsplot for SN Ratio
7.2.1 CONFORMATION TEST:-
Hardness is larger-the-better type quality characteristic. Therefore higher values of hardness are considered to be optimal. It is clear from Graph that hardness of is highest at third level of Welding Current, third level of Welding Voltage and Second level of Welding Bevel . Process parameters and their selected optimal levels are given below
Welding Current A (3) 180 A
Welding Voltage B (3) 22 V
Welding bevel angle C(2) 65
7.3 HARDNESS ,IMPACT TEST RESULT AND DISCUSION
Taguchi Analysis: HARDNESS,IMPACT versus AMPS, VOLT, BEVEL
TABLE 7.3.1 S/N ratios values for the HARDNESS,IMPACT
T.NO Designation AMPS VOLT BEVEL IMPACT HARDNESS SNRAT
1 A1B1C1 140 18 55 20 80 28.7676
2 A1B2C2 140 20 65 20 73 28.7166
3 A1B3C3 140 22 70 37 82 33.5695
4 A2B1C2 160 18 65 14 89 25.8267
5 A2B2C3 160 20 70 19 82 28.3583
6 A2B3C1 160 22 55 17 84 27.4449
7 A3B1C3 180 18 70 16 90 26.9576
8 A3B2C1 180 20 55 11 86 23.7677
9 A3B3C2 180 22 65 17 95 27.4824
TABLE : 7.3.2 Response Table for Signal to Noise Ratios-Larger is better
Level AMPS VOLT BEVEL
1 37.87 38.71 38.41
2 38.58 38.08 38.60
3 23.17 26.86 27.01
Delta 1.24 0.69 0.19
Rank 1 2 3
TABLE: 7.3.3 Response Table for Means
Level AMPS VOLT BEVEL
1 78.33 86.33 83.33
2 85.00 80.33 85.67
3 90.33 87.00 84.67
Delta 12.00 6.67 2.33
Rank 1 2 3
7.3.1 CONFORMATION OF TEST:-
Snice we required larger-the-better type quality characteristic. Therefore higher values of are considered to be optimal. It is clear from Graph that hardness of is highest at third level of Welding Current, third level of Welding Voltage and Second level of Welding Bevel . Process parameters and their selected optimal levels are given below
Welding Current A (1) 140 A
Welding Voltage B (3) 22 V
Welding bevel angle C(3) 70
7.4 ULTRASONIC TEST :-
TABLE -7.4.1 UT REPORT
S.NO ITEM NO /
LOCATION MATERIAL
Components THICKNESS INDICATIO
NS RESULT
1. TP-1 SS309 10MM – ACCEPT
2. TP-2 – ACCEPT
3. TP-3 ICP &Por REJECT
4. TP-4 – ACCEPT
5. TP-5 – ACCEPT
6. TP-6 – ACCEPT
7. TP-6 – ACCEPT
8. TP-6 Cr REJECT
9 TP-9 – REJECT
7.4.1 CONFORMATION OF TEST :-
From the above results we can conclude that the sample pieces with the combinations A1B3C3, A3B2C1 and A3B3C2 doesn’t qualified for the test and rejected and thus we can exclude from the process optimization parameters since they are unfit
CHAPTER 8
CONCLUSION
Based on the investigation following conclusion are drawn MIG Welding process is very successful to join SS309. Based on the S/N ratio analysis and ANOVA, the process parameters which significantly affects the IMPACT andHARDNESS was current,bevel and Voltage.
The optimum value was predicted using MINITAB 17 software.
The effect of parameters on penetration can be ranked has , current ,bevel and voltage.
Argon gas has shielding gas has been found to work satisfactory.

In this approach the third combinationsA1B3C3(140A 22v 70) is predicted as the optimized values within the constrained limits for toughness in impact
In this approach the third combinationsA1B3C2(180A 22v 65) is predicted as the optimized values within the constrained limits for hardness
The experimental results confirmed the validity of the used Taguchi method for enhancing the welding performance and optimizing the welding process parameters in MIG welding on SS309.

From UT we can conclude that the sample pieces with the combinations A1B3C3, A3B2C1 and A3B3C2 doesn’t qualified for the test and rejected and thus we can exclude from the process optimization parameters since they are unfit
MIG welding can be used successfully to join SS309. The processed joints exhibited better mechanical and metallurgical characteristics. The joints exhibited 90-95% of parent material’s Hardness value.
The specimen failures were associated depending upon the improper changes of heat value. In our experiment we found out the input parameter value 140 AMPS VOLT-18 Bevel angle -55º the best value and it does not create any major changes and failures in the testing process
The toughness value of the MIG welded dissimilar steel was comparatively higher value (140 AMPS VOLT-18 Bevel angle -55º) than other value. It also induces high tensile strength. Finally we concluded that in this project investigation the 140 AMPS VOLT-18 Bevel angle -55º is the best parameter for Disimilar-10 MM thickness plate for obtain the good weldment state
According to the Taguchi’s design and optimized parameter is value for Impact strength the 10 mm plate of dissimilar steel 140 AMPS VOLT-22 Bevel angle -65º

CHAPTER-9
REFERENCE
J. Dutta Department of Mechanical Engineering, National Institute of Technology Karnataka, Surathkal, India*Corresponding EXPERIMENTAL and analytical investigation of thermal parameters Developed in high carbon steel joints formed by gta welding
Vishnu V.S Numerical Analysis of Effect of Process Parameters on Residual Stress in a Double Side TIG Welded Low Carbon Steel Plate. IOSR Journal of
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M.Pal Pandi,et al Thermal Analysis on Butt Welded Aluminium Alloy AA7075
Plate Using FEM International Journal of Engineering Research (ISSN:23196890)(online),2347-5013(print)Volume No.3, Issue No.2, pp : 116-120.
M SUNDAR Assessment of residual stress and distortion in Welding by finite element method proceedings of the International conference on mechanical engineering 2005
N. AKKUS Thermomechanical Analysis of Arc Welded Joint by Finite
Element Method International Congress on Advances in Welding Science and Technology for Construction, Energy and Transportation Systems (AWST – 2011) 24-25 October 2011, Antalya, Turkey
FANRONG KONG Numerical and experimental study of thermally induced residualstress in the hybrid laser–GMA welding process Journal of Materials Processing Technology
LI YAJIANG Finite element analysis of residual stress in the welded zone of a high strength steel Key Laboratory of Liquid Structure and Heredity of Materials,
Ministry of Education, Shandong University,Jinan 250 061, China
M.N.CHOUGLULE Experimental and analytical study of thermally induced residual stresses for stainless steel grade using gmaw process. 5th International & 26th All India Manufacturing Technology, Design and Research Conference (AIMTDR 2014) December 12th -14th, 2014, IIT Guwahati, Assam, India
S.KOU Welding Thin Plates of Aluminum Alloys A Quantitative Heat-Flow Analysis
A. ANCA 3d-thermo-mechanical simulation of welding process Mec´anica Computacional Vol. XXIII, pp. 2301-2318 G.Buscaglia, E.Dari, O.Zamonsky (Eds.) Bariloche, Argentina, November 2004
L.A.JAMES Fatigue-Crack Propagation Behavior of Several Pressure Vessel
Steelsand Weldments
A.D WILSON Properties and behaviours of modern A 387 cr-Mo steels
APPALA NAIDU Hot Corrosion Studies on Welded dissimilar Boiler steel in Power plant environment under cyclic condition. International Journal of ChemTech ResearchCODEN( USA): IJCRGG ISSN : 0974-4290 Vol.6, No.2, pp 1325-1334, April-June 2014
A.RASOOL Influence of post weld heat treatment on the HAZ of low alloy steel weldments .The American society of Mechanical Engineers

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