Effects of tempering temperature on fatigue crack propagation behavior of high-strength low-alloy D6AC steel plasma arc welds

The objective in this study was to elucidate fatigue crack propagation in D6AC steel plasma arc weldments (PAWs) that underwent post-weld (PW) tempering at 300 °C, 450 °C, or 600 °C. PW tempering at 600 °C was shown to enhance the refinement of the microstructure and thereby increase resistance to the growth of fatigue cracks. Surfaces with fatigue fracturing presented quasi-cleavage planes and intergranular fracture modes. The zigzag nature of the crack path (i.e., crack deflection) may contribute to the retardation of fatigue crack propagation.