Experimental analysis of tensile strength in Stainless Steel-304 and Mild Steel-1144 on various process parameters of gas metal arc welding by using Taguchi technique

Experimental analysis of tensile strength in Stainless Steel-304 and Mild Steel-1144 on various process parameters of gas metal arc welding by using Taguchi technique

Experimental analysis of tensile strength in Stainless Steel-304 and Mild Steel-1144 on various process parameters of gas metal arc welding by using Taguchi technique

1Vijay, 2Arshad Mujtaba Azad, 3Ravinder Chaudhary

Student M.Tech Manufacturing Student YIET Yamunanagar. Assistant Professor in Mechanical at YIET Yamunanagar. Assistant Professor in Mechanical at SKIET, Kurukshetra.

1. INTRODUCTION

   Welding is a fabrication process that joins materials permanently, usually similar or dissimilar metals by the use of heat causing fusion with or without the application of pressure. Arc welding among these welding processes is the most popular welding process the world over. Arc welding in its present form appeared on the industrial scene in 1880s. Arc welding however, was not accepted for fabrication of critical components till about 1920. However, the demand for large scale production of heavy items like ships, pressure vessels, construction of bridges etc. provided the necessary impetus for welding to come of age and the Second World War firmly established it as the major fabrication process.

   Fig 1.1: Principal Of Metal Arc Welding.

   The figure 1.1 shows the principal of Metal Arc Welding process. In arc welding processes an electric arc between an electrode and a workpiece or between two electrodes is utilized to heat the joint to be welded. Most of these processes use some shielding gas while others employ fluxes or coatings to protect the weld pool from ill effects of the atmosphere. Welding processes widely used in industry include oxy- acetylene, manual metal arc or shielded metal arc (SMAW), submerged arc (SAW), gas metal arc (GMAW), gas tungsten arc (GTAW), resistance and thermit welding.

   Lu and Kou (Ref. 3) measured power and current density distributions using a split copper block. Based on the analysis by the Abel inversion method, the shape of power and current distribution were found out to be Gaussian density functions, so the arc shape could be described by the total magnitudes (i.e., total heat input and current) and Gaussian distribution parameters. the shape of the weld pool and bead shape are also strongly affected by the flow of plasma in the welding arc. The forces exerted by the arc plasma jet on the weld pool are the arc stagnation pressure and drag force. Arc pressure acts on the weld pool surface in the normal direction, depressing the molten deposit. Arc pressure density distribution on the weld pool surface has also been investigated for GTAW.

   The mechanism was studied by Heiple and Roper. They proposed that the final weld shape can be significantly altered by variations of the surface active elements (e.g., sulfur) that changes the direction of surface tension gradient induced flow (Marangoni flow) in GTA welding conditions. Based on understanding the well known forces and heat input in the weld pool, many researchers simulated arc welding processes and studied weld pool convection, the formation of the weld pool and molten droplets, droplet transfer, and solidified weld bead shape. The idea of solving for the shape of the free surface of a fluid volume as a static energy minimization problem. Wang and Tsai investigated the dynamics of periodic filler droplets impinging onto weld pool and phase change,

   using VOF technique that can handle a transient deformed weld pool surface and the continuum model (Kuk et al. 2004, Murugan and Parmar, 1994).GMAW welding process overcome the restriction of using small lengths of electrodes and overcome the inability of the submerged-arc process to weld in various positions. By suitable adjusting the process parameters, it is possible to weld joints in the thickness range of 1- 13 mm in all welding position . (Jang et al. 2005, Praveen and Yarlagadda, 2005).The American Welding Society refers to the process Gas Metal Arc Welding process to cover inert as well as active shield gasses. GMAW is basically a semi automatic process arc lengths of electrode and the feeding of the wire are automatically controlled. The welding operators job is reduced to positioning the gun at a correct angle and moving it along the seam at a controlled travel speed. Hence less operator skill is required with this process as compare to TIG and manual metal arc process. Yet basic training is required in the setting up of the equipment and manipulation of the gun must be provided to the operator to ensure quality GMAW welding. Lowke et ul. simplified the model by putting boundary conditions for elrctric potentiai into the rod electrode. In their model, they solved the mas cmtinuity and consemation equations for momentum and energy only They neglectcd the cathode sheath between the electrode and the arc. Although in this model thcre is no need to pre-define the cathode çurrent density. the rcsults are dependent to some extent on the cathode surfxe temperature.

2. METHODOLOGY ADOPTED

   1. aguchi Technique: Taguchi method is applied for the current study for Experimental analysis of tensile strength in Stainless Steel-304 and Mild Steel-1144 on various process parameters of gas metal arc welding by using Taguchi technique. Professor Taguchi developer of robust designs and advocates a philosophy of quality engineering that is broadly applicable. The fundamental principle of robust design is to improve the quality of a product by minimizing the effect of the causes of variation without eliminating the causes.Professor Genichi Taguchi introduced his approach using experimental design for

      • Designing products or processes so that they are robust to environmental condition.

      • Designing/developing products so that they are robust to component variation.

      • L-9 orthogonal array is selected for the current research work.

   B. Material Used

   In the present study Stainless Steel-304 and Mild Steel- 1144 is selected as a workpiece for working on Gmaw The Electrode Used Is E-6010 cellulosic ,E6012 rutile. Welding is performed on Stainless Steel and Mild Steel flat plate of 100*75*8 dimension By using( Uttam arc

   welding transformer) Welding machine. The different electrodes use for the process is arc of diameter 3mm.

   2. Experimental set up

   The purpose of this study is analysing the effect of tensile strength on GMAW in Stainless Steel-304 and Mild Steel-1144. Tensile testing, also known as tension testing, is a fundamental material test in which a sample is subjected to uniaxial tension until failure. The results from the test are commonly used to select a material for an application. The pieces welded by welding machine using different electrodes.is as shown in the figure below.

   Fig. 1.2 Typical SMAW Welded with E-6012(Rutile)

   Electrode

   The different electrodes use for the process is arc of diameter 3mm. eighteen no. of pieces welded by welding machine using different electrodes. In the present study, three 3-level process parameters i.e. Arc current, Arc voltage and welding speed are considered. The values of the welding process parameters are listed in Table .L-9 orthogonal parameters are selected for the present research work.anova is also performed and is as shown in below discussion.

   Table 1: Parameters & their levels

   A

   Parameters	Code	Level 1	Level 2	Level 3
   Welding Current (Amp)	85	95	110
   Arc Voltage (Volt)	B	30	32	34
   Welding Speed (mm/sec)	C	3.57	3.82	5.74

   After using this value on minitab software design of experiment i.e L-9 Orthogonal array is prepared which is shown as below :-

   RUN	CURRENT (amp)	VOLTAGE (volt)	SPEED(mm/SEC)
   1	85	30	3.57
   2	85	32	3.82
   3	85	34	5.74
   4	95	30	3.82
   5	95	32	5.74
   6	95	34	3.57

   Table 2 : Design of Experiments

   7	110	30	5.74
   8	110	32	3.57
   9	110	34	3.82

   Table 1.2: analysing the tensile strength on various process parameters

   Sr. No	Current	Voltage	Speed	Tensile Strength Kgf /mm2
   1	85	30	3.57	422.11
   2	85	32	3.82	423.37
   3	85	34	5.74	424.63
   4	95	30	3.82	425.71
   5	95	32	5.74	424.89
   6	95	34	3.57	425.93
   7	110	30	5.74	427.01
   8	110	32	3.57	428.51
   9	110	34	3.82	431.73

   In this study we noticed that how tensile strength vary by changing the above parameter i.e. welding current etc. E6010 electrode coating by 40% cellulose 25% titanium oxide, 20% mg silicon, 15% Fe-Mn bonded with sodium or potassium silicate.

3. RESULTS AND DISCUSSIONS Experimental set up show the effect of the three control factors on tensile strength. The S/N ratio response table and response graphs are shown for S/N ratio for tensile strength is shown Fig.3.

   Main Effects Plot for SN ratios

   Data Means

   As we obtained from the minitab software that according to the design of experiment the value of tensile strength is for (424.63 N/mm2) at( 85 Amp) current & (431.77 N/mm2) at (110amp). The behavior can also be represented on mean graph as shown in the figure above . The value of tensile strength increases with increase the current and elongation percentage is also increase. On increasing the voltage supply the tensile strength goes on increasing and reach to maximum value at 428.32 at higher value of voltage this is due to the fact that as we increase the voltage supply the current increases that is used in SMAW welding, the bigger the Al materials produced especially on weld metal area. However in HAZ area, the dense material produced on 110 A. The other influencing factor on tensile strength is current in SMAW. There is close relation between the welding current and mechanical proper-ties of weld metal on one hand and normalising temperatures and mechanical properties on the other hand. In general, The current variables used are 85,95,110 effect so much on the base metal as the current increase hardness also increase. As the heat input increases the temperature gradient of the solidifying weld metal in-creases. Also, the shape and size of weld pool is signifi-cantly affected by heat input, the weld pool becomes elongated as the heat input increases. formation of columnar dendrites in the weld metal and also increases the level of residual stress in the weld metal.

   Residual Plots for T.STRENGTH

   Normal Probabilit y Plot Versus Fit s

   99

   0.2

   Residual

   90

   Percent

   0.0

   50 -0.2

   10 -0.4

   52.650

   52.625

   Current

   Voltage

   1

   -1.0

   -0.5

   0.0

   Residual

   0.5

   1.0

   -0.6

   423

   426

   Fitted Value

   429

   432

   52.600

   Mean of SN ratios

   52.575

   52.550

   Speed

   85

   52.650

   52.625

   95 110 30 32 34

   6.0

   Frequency

   4.5

   3.0

   1.5

   0.0

   Hist ogram Versus Order

   0.2

   Residual

   0.0

   -0.2

   -0.4

   -0.6

   -0.6

   -0.4

   -0.2

   0.0

   0.2

   1 2 3 4 5 6

   7 8 9

   52.600

   52.575

   52.550

   Residual

   Observation Order

   3.57

   3.82

   5.74

   The residuals plots vs tensile strength is given in the

   Signal-to-noise: Larger is better

   Fig 3 : Effect of control factors on tensile strength for s/n ratio

   Main Effects Plot for Means

   Voltage

   Current

   Data Means

   figure above in very first figure process parameters are randomly distributed on the straight line which shows the goodness of fit.

4. CONCLUSION

429.0

427.5

426.0

Mean of Means

424.5

423.0

429.0

427.5

426.0

424.5

423.0

85

Speed

3.57

95

3.82

110 30 32 34

5.74

In this paper influence of process parameters on tensile strength was investigated. The parameters affecting the response were obtained using ANOVA and the graph was plotted. From the analysis, it is concluded that:

1. From the above discussion it is concluded that tensile strength is increased with the increasing of current and voltage

2. Secondly as the weld speed is increasing

   Fig 4 : Effect of control factors on tensile strength for means

   The tensile strength first increase upto a limit of 428 bt then rapidly goes on decreasing mode.

3. For wire crater depth (d), µm, weld speed rate is the most significant parameter with 3.57 to

3.82 contribution.

REFERENCES

[1]. Heiple, C. R., and Roper, J. R. 1982. Mechanism for minor element effect on GTA fusion zone geometry. Welding Journal 61(4): 97-s to 102-s. 8. Heiple, C. R., and Burgardt, P. 1985. Effects of SO2 shielding gas additions on GTA weld shape. Welding Journal 64(6): 159-s to 162-s.

[2]. Lu, M., and Kou, S. 1988. Power and current distributions in gas tungsten arc welding. Welding Journal 67(2): 29-s to 34-s.

[3]. Wang, Y., and Tsai, H. L. 2001. Impingement of filler droplets and weld pool dynamics during gas metal arc welding process. Int. J. of Heat and Mass Transfer 44: 20672080. 22. Chiang, K. C., and Tsai, H. L.

1992.Shrinkage-induced fluid flow and domain change in two-dimensional alloy solidification. Int. J. of Heat and Mass Transfer 35: 17631770.

[4]. J. M. Kuk, K. C. Jang, D. G. Lee, I. S. Kim, Effects of temperature and shielding gas mixture on fatigue life of 5083 aluminum alloy, Journal of Materials Processing Technology, 2004, Vol. 155-156, , pp.1408-1414.

[5]. P. Praveen, P.K.D.V. Yarlagadda, M.J. Kang, Advancements in pulse gas metal arcwelding, Journal of Materials Processing Technology Vol. 164-165, 2005, pp.1113-1119.

[6]. K. Sindo, Welding Metallurgy, 2nd Edition, John Wiley & Sons, New York, 2003, pp. 199-206.