Mechanical properties and microstructural analysis of 304 stainless steel by TIG welding

Abstract

Gas tungsten arc welding is the process repairing and widely used in heavy engineering for joining metal. It can be uses for various type of metal and application. The aim of this project is to study the effects of 304 stainless steel with 3 mm thickness on mechanical properties and its microstructure analysis using gas tungsten arc welding method. The variables set up in this project were current, gas flow rate and welding direction upon rolling direction of stainless steel sheet. Type of filler metal used in this project was ER 308L with 1.6 diameter. Testing that carried out were tensile test, Vickers macro hardness test with 10 kgf load and microstructure analysis by using optical microscope. The maximum percentage difference in ultimate tensile strength between longitudinal and transverse welding was 15 %. From the mechanical properties procedures, the strength of the weld metal was obtain. The highest tensile strength were found at longitudinal welding with 820 MPa by using 80 A and 12 l/m gas flow rate. Meanwhile for hardness testing, the most important zone to be focused were heat-affected zone (HAZ) and weld metal (WM). The highest hardness value of weld metal were found at longitudinal welding which is 185 HV. The integrity of the welding tested by using tensile test and hardness test with different amount of current and gas flow rate.