Experimental Investigation and Process Parameter Optimization of Ss316 Weld in GMAW using Taguchi Grey Relational Analysis

Abstract

This paper focuses on the Gas Metal Arc welding (GMAW) of SS316 and optimization of its process parameters through Grey Relational Analysis (GRA) Technique. The variables selected for investigation are current, torch travel speed, gas flow rate and feed rate of filler wire. Experimental runs are designed using L18 orthogonal Taguchi approach. The quality of the weld is ensured by assessing Impact Strength, Hardness and Ultimate Tensile Strength (UTS). When travel speed is 35 cm/min, material deposition and penetration are excellent which resulted in better weld strength. Phase transformation occurs in welded zone from alpha ferrite to martensite, owing to this the hardness value of weld zone is higher than the Heat Affected Zone (HAZ). The results revealed that the higher gas flow rate leads to a reduction in the area of HAZ, which results in better toughness value. The fractography is studied with the aid of Scanning Electron Microscope (SEM). Plastic flow, dimples and shear lip formation are clearly visible in SEM. The maximum weld strength is obtained when welded at current of 140 A, gas flow rate of 15 l/min, travel speed of 35 cm/min and the wire feed at the rate of 4 m/min.

Keywords- GMAW, Taguchi, GRA, Mechanical properties, HAZ, SEM