Weld Profile Optimization on Weld Speed & arc ...

Jour of Adv Research in Dynamical & Control Systems, 11-Special Issue, July 2017

Weld Profile Optimization on Weld Speed & arc Length Parameters of TIG Welding on Al-SiC Composite Sivachidambaram Pichumani, PhD Research Scholar, School of Mechanical Engineering, SASTRA University, Thanjavur, India. E-mail:[email protected] Raghuraman Srinivasan, Professor, School of Mechanical Engineering, SASTRA University, Thanjavur, India. E-mail:[email protected]

Abstract--- Study & optimization on the effects of TIG welding parameters of welding speed & arc length on weld profile and weld bead appearance of Al-SiC composite are experimentally carried out to achieve the optimal weld condition. Mathematical model is developed using Design Expert® statistical software for predict and optimizing the experimental results using regression equations. From the weld profile & weld bead appearance, arc length of 2mm with a welding speed of 2mm/s results in maximum weld penetration. Increase in arc length & welding speed reduces the welding depth & increases in weld width. From the mean effect study it is observed that Arc length has higher effect on weld depth & weld width than the welding speed.

I.

Introduction

In metal matrix composite, aluminium metal matrix is easy for processing because of its lower melting temperature, lower density and corrosion resistance properties. In aluminium matrix the most commonly used reinforcement are SiC, TiB2, TiC, B4C [1]. Due to higher hardness of SiC and small density difference between aluminium & SiC, facilitates for usage of SiC as more widely used reinforcement for aluminium [2]. Stir casting process is one of the mainly used processes for the manufacturing of aluminium silicon carbide (AlSiC) composite. It gives homogeneous mixture of aluminium metal matrix with silicon carbide particle reinforcement [3]. It is the most suitable and economical way of producing Al-SiC composite while compared to other manufacturing processes such as powder metallurgy route and spray coating process [4]. Aluminium - silicon carbide composite material is well known for its good wear resistance [5] and higher strength to weight ratio [6]. Gas Tungsten Arc Welding (GTAW) also known as Tungsten Inert Gas (TIG) welding shows high quality weld compared with other arc welding processes. Non ferrous metals requires quality weld with reduced defects and improved mechanical properties, hence TIG is more suitable for welding of Al-SiC composite [7].

II.

Experimentation

Autogenous welding is performed on Al-8%SiC composite material with a plate thickness of 5mm using ADOR CHAMPTIG 300AD welding machine. Other welding parameters considered during welding are provided in table 1. Table 1: Welding Parameters Parameter Condition Current type AC current Welding current 100A Electrode diameter 3.2 mm Electrode material 2% Th - Tungsten electrode Argon flow rate 18 l/min Argon flow pressure 1 Kg/cm2 Macro structure is revealed through etching the welded samples using strong acidic solution of (100ml HF, 50ml HCl, 30ml HNO3 and 20ml H2O). This macro structures observed are recorded using high magnification digital camera. Macro structure shows the weld profile such as weld depth, weld width and weld bead appearance.

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III.

Results & Discussion

The influence of welding speed & arc length on weld bead of the weldment during TIG welding of Al-SiC composite observed during experimentation is represented in the following figures. From figure 1, it is inferred that increased arc length increases weld width under the following condition. Arc length of 1mm has lesser weld width of 3.5mm and arc length of 3mm has greater weld width of 5mm. Arc length of 2mm shows weld width of 4mm.

Figure 1: Weld Bead Appearance at Various Arc Length and Welding Speed 1 In figure 2, arc length of 3mm with welding speed of 3mm/s shows higher weld width of 5mm compared with the other two welding condition. Arc length of 1mm and welding speed of 2.5mm/s results in slightly reduced weld width of 4mm. Arc length of 2mm and welding speed of 3mm/s has 4.5mm weld width. Macro structures observed from figure 3 are tabulated in table 2.

Figure 2: Weld Bead Appearance at Various Arc Length and Welding Speed 2

Figure 3: Macro Structure for Different Arc Length and Welding Speed

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Table 2: CCTIG Weld Profile for Various Arc Length and Welding Speed

IV.

Conditions

Weld depth (mm)

Weld width (mm)

Weld depth to width ratio

Arc Length 2mm, Welding Speed 2mm/s Arc Length 1mm, Welding Speed 3mm/s Arc Length 3mm, Welding Speed 2.5mm/s Arc Length 2mm, Welding Speed 3mm/s Arc Length 3mm, Welding Speed 3mm/s Arc Length 1mm, Welding Speed 2.5mm/s

2 1.5 1 2 1.5 1.5

3.5 4 5 4.5 5 4

0.57 0.38 0.20 0.44 0.30 0.38

Mathematical Model

Effect of welding speed, arc length & the interaction effects on weld depth & weld width are studied using Design Expert® statistical software. Regression equations developed are shown in table 3. Correlation co-efficient shows that the weld depth and weld width are consistent. These regression equations are used to optimize the welding speed and arc length in order to obtain the maximum weld depth with minimum weld width. R – Regression equation A – Welding speed B – Arc length r2 – Correlation coefficient Table 3: Regression Equation for Weld Profile Response Weld depth Weld width

Regression equation(R) R=1.6-(0.05*A)-(0.25*B)+(0.25*A*B) R=2.35+(0.4*A)+(0.5*B)

Correlation coefficient (r2) 0.91 0`94

Table 4: Mean Effect Study Level 1 2 3 Delta Rank Percentage

Welding Speed 8.275 2.175 3.831 6.1 1 53.31

Arc Length 3.838 6.782 1.439 5.343 2 46.69

Figure 4: Weld Depth – (arc length vs. welding speed) Table 4 shows the mean effect study on welding speed and arc length of weld profile. It is observed that the welding speed has slightly higher effect of 53.31% than the arc length of 46.69% on the weld profile. From figure 4 and 5, increase in arc length & welding speed reduce the welding depth & increases in weld width. Arc length has higher effect on weld depth & weld width than the welding speed.

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Figure 5: Weld Width – (arc length vs. welding speed) Desirability graph in figure 6 represents the optimized parameters of arc length of 2mm & welding speed of 2mm/s for TIG welding. Increase in arc length leads to increase in weld width but reduces the weld depth & depth to width ratio. Increase in welding speed, reduces the weld depth and weld width with slight reduction in depth to width ratio.

Figure 6: Desirability – (arc length vs. welding speed)

V.

Conclusion

In Tungsten Inert Gas (TIG) welding, study on welding speed & arc length on weld profile and weld bead appearance are experimentally carrie optimized welding conditions. Macro structure observed using higher magnification camera shows maximum weld depth of 2mm, minimum weld width of 3.5mm wit d out mathematical model has been developed to obtain h a clean weld bead appearance using the TIG welding parameter of arc length of 2mm & welding speed of 2.5mm/s. Increase in arc length & welding speed reduces the welding depth & increases the weld width. Arc length has higher effect on weld depth & weld width than the welding speed. .

Acknowledgment The authors express their sincere gratitude to the Vice-Chancellor of SASTRA University for allowing us to pursue our research work in the School Mechanical Engineering.

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