The Effect of Quenching Mediums on Heat Treatment Properties of Multi-pass Welding of 0.3%C-Cr Mo V Steel

Abstract

AbstractThis paper brings out the correlation between microstructure and mechanical properties of 0.3% C-CrMoV steel, welded with manual gas tungsten arc welding (GTAW) process with a combinations of weld parameters as per the principle of Taguchi’s design of experiments (DOE). After welding the test plates, test specimens were cut from it, hardened and tempered, quenched in forced air, water, and oil. Test samples were drawn from these combinations and microstructure evaluation was studied. Mechanical properties like hardness, tensile strength, yield strength, %elongation, % reduction in area, and impact strength were evaluated. The fracture morphology features of failed impact specimens were observed using scanning electron microscope. The mechanical properties of the weldment were compared and it was observed that, the test specimens quenched in oil give maximum UTS 1430 MPa, water quenching gives 1395 MPa, and forced air cooling gives 1260 MPa. Maximum weld strength obtained with the combinations of root gap of 1 mm, number of passes two or three and oil as quenching medium. All the tensile test specimens are broken outside the weldment during tensile testing. The maximum impact properties were obtained from the test plates welded in annealed condition with multi-pass welding, which was 52 J. When forced air was used as a quenching medium, with multi-pass welding, it gives lower tensile strength and higher percentage elongation and impact strength. This study was an attempt to optimize the weld parameters, heat treatment methods, quench mediums, and correlate mechanical properties with microstructure.Keywords0.3%C-CrMoV steelGTAWUTSHardeningTemperingQuenching mediums