STUDIES ON THE EFFECTS OF MULTIPASS WELDING ON MECHANICAL PROPERTIES OF MILD STEEL ON SMAW JOINT

Abstract

The modern industries are still relying on welding to join two metals by fusion between the base metal and the filler material. In this Research, the focus is the multi-pass welding, as this technique is used when it exceeds the limitations of two-pass welding technique and is widely used in the industry like oil and gas, constructions and productions. The study on the effects of multi-pass welding on the mechanical properties of mild steel on shielded metal arc welding (SMAW) joint will unravel a better understanding on multi-pass welding by different types of filler material and number of welding passes. The design of experiment (DOE) for this study is two-level ANOVA which will be an essential tool to determine the outcome of this study. In detail, two-level ANOVA technique is used where two types of electrodes (E6013 and E7016) and two different numbers of passes (3 passes and 5 passes). The base material for this study is mild steel as it has good weldability and the specimens will undergo tensile and hardness test in order to obtain experimental results. After all the results are taken, all data computed and analysed using full factorial design of experiment. The outcome of the multi-pass study can be concluded that there are significant differences in the factors that were analysed. The interaction between electrode and passes shows that the interaction is not parallel with each other. Tensile strength and hardness of welded metal however there are no differences in hardness when the passes increased. The results for Rockwell Hardness test shows that the highest hardness recorded is 83.69 HRG for 3 passes, while UTS recorded was 569.46 MPa for 5 passes, both using electrode E7016. Based on the response optimizer done with Full Factorial Design of Experiment, electrode E7016 is the ideal electrode used in this study for hardness and tensile