The Effect of Heat Input on the Mechanical and Corrosion Properties of AISI 304 Electric ARC Weldments

Abstract

The mechanical and corrosion performances of austenitic stainless steels arc weld joints in service environments have been established to be influenced by the process parameters used in carrying out the welding process. In this work, the mechanical and corrosion resistance of electric arc weld joints of AISI 304 was investigated at varying process parameters. The welding was carried out using ESAB LHF 400 industrial welding machine. The microstructure of the weld joints was examined using optical microscopy and scanning electron microscopy. The micro-hardness and tensile strength of the welded samples were determined with the aid of Vickers micro-hardness tester and Instron universal testing machine respectively. The electrochemical corrosion of the samples in 3.5% NaCl solution was investigated using potentiostat. The results revealed that good quality arc weld joints are obtainable at a welding current range of 90-130 A and welding speed of 1.7-4.0 mm/s. The microstructure of the weld joints comprises austenite and delta-ferrite phases. The hardness value of the weld joints (ranging within 234-275 HV0.1) was found to decrease with increase in the heat energy per unit length of weld. The optimal ultimate tensile stress of 550 MPa was obtained at a heat energy input of 9680 J/mm, whereas the value obtained for the as-received AISI 304 is 560 MPa. The corrosion performance of the arc weld joints is close to that of the as-received AISI 304. However, the corrosion performance of the weld joints decreased with increase in the heat energy input.