AN INVESTIGATION INTO THE AISI 304 ELECTRIC ARC WELDING FOR OPTIMUM MECHANICAL AND CORROSION PERFORMANCE

Abstract

The mechanical and corrosion performance of austenitic stainless steels arc weldments hasbeen established to be directly related to the process parameters used in carrying out thewelding. In this work, the mechanical and corrosion resistance of electric arc weldments ofAISI 304 was investigated for varying process parameters. Electric arc welding of 304austenitic stainless steel samples was carried out using ESAB LHF 400 industrial weldingmachine at different process parameters. The microstructure of the weldments 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 testerand Instron universal testing machine, respectively. The electrochemical corrosion of thesamples in 3.5% NaCl solution was investigated, using potentiostat. The results revealed that good quality arc welded joints were obtainable at a welding current range of between 90-130A and welding speed of 1.7-4.0 mm/s. The microstructure of the weldments comprisesaustenite and delta-ferrite phases. The hardness value of the weldments (ranging within234-275 HV0.1) was found to decrease with increase in heat input per unit length of weld. Theoptimal ultimate tensile stress of 520 MPa was obtained at a heat input of 9680 J/mm,whereas the value obtained for the as-received AISI 304 is 544 MPa. The corrosion performance of the arc weldments is close to that of the as-received AISI 304. However, the corrosion performance of the weldments decreased with increase in the heat input.