Effects of Welding Speed on the Microstructure, Mechanical Properties and Corrosion Resistance of the Electron Beam Welded AISI 321 Plates

Abstract

The intention in this research work is to investigate the effect of welding speed in electron beam (EB) welded 18mm thick plates of AISI 321. In this work, an attempt is made to study the effect of two different welding speeds on the microstructure, mechanical properties and corrosion resistance of the welded joints. The results in the study show that bead width, reinforcement area, dendritic length and inert dendritic spacing vary for the different heat inputs. The microstructure conducted using optical microscope and scanning electron microscope (SEM) shows the presence of lathy and vermicular ferrites in the weld bead. In addition, the ferrite measurements and the X-ray diffraction (XRD) studies indicate the difference in the ferrite content of the two beads. The fusion boundary has the highest microhardness of about 171.9 HV. The maximum toughness of 129.3J was found at the top region of the weld. The percentage elongation in the tensile test had shown increase in the root region of the welds. The rate of intergranular corrosion in mm per year was calculated and was found to be 13% more in the in the welds with more heat input.