Statistical analysis on influence of groove patterns on the mechanical strength of friction-welded SAE1018 steel

This research work focuses on the impact of various groove pattern, groove depth, and their combination on SAE 1018 mild steel rod friction welded mechanical properties. SAE 1018 steel was used, with a modified vertical milling machine with parameters of the Taguchi's L9 Orthogonal array used in the welding process. The groove pattern and groove depth which provides maximum UTS were determined with the help of ‘Minitab 17 software analysis’. The parameters with the best characteristics of measurement system were grooves made on the stationary and rotating specimens, equal to 1.5 mm groove depth, and hash pattern. The initial optimization predicted the UTS to be 542 MPa however the experimental analysis resulted in a value of 564 MPa which is greater than the base material UTS of 436 MPa. It was also observed from ANOVA that the groove on both specimens had the greatest effect on the UTS percent contribution of 58.65% followed by the depth and pattern percent contribution of 20.42% and 13.55% respectively. Hardness analysis pointed to the maximum microhardness value of 300 HV at the weld center and the minimum value of 200 HV at 15 mm from the center. The difference in hardness between the two rotating and the two stationary discs was ascribed to increased frictional and plastic flow on the rotating side. XRD characterization of the samples supported the findings of the presence of both α-Fe and FeO phases for all the samples and MnO was detected primarily in the Z Groove pattern.