Evaluating Microstructural and Hardness Variations in Time Dependent Multipass Welded Mild Steel
This paper investigates the microstructural induced hardness variation in multirun welded plain carbon steel at different interpass time. Beveled 16mm thick mild steel samples were welded in 2 and 4 passes at interpass time of 90, 120 and 240s respectively via manual metal arc. The result showed that the differences in hardness values of the fusion zone and heat affected zone reduce as interpass time increases for both 2 and 4 runs. The effect was however quite distinct in the 4 runs welding cycle. In the 2 run cycle, the fusion zone and heat affected zone merge at 100 seconds; while in the 4 runs cycle, the merging occurred at 25 seconds; indicating that the higher the multipass, the shorter the time required to produce uniformity in hardness and structural homogeneity. Thereby increasing the resistance of the weld to crack susceptibility and failure. At these instances, the microstructure revealed fine grained pearlite interpassed in martensite.
Prof. A.O. Akii Ibhadode, A.I. Igbafe and B.U. Anyata
M. O. H. Amuda et al., "Evaluating Microstructural and Hardness Variations in Time Dependent Multipass Welded Mild Steel", Advanced Materials Research, Vols. 62-64, pp. 345-351, 2009