Papers by Author: Chun Guo Zhang

Abstract: The present work dealt with the fatigue and residual stress (RS) effects of a soft buffer layer (BL) between the parent metal and the weld metal (WM) on welded high-strength low-alloy (HSLA) steel. Six strategies were pursued by varying BL thickness and changing U-notch position with respect to the WM in extended-compact tension specimen. The U-notch position was changed to study the effect of welding RS field, acting along the fatigue crack growth path. The welded HSLAs with BLs strategies were compared to the specimens without BLs strategies, before and after releasing RS respectively. The results demonstrated that the incorporation of a thin BL of 4 mm significantly reduced the fatigue crack growth rate (da/dN) when the RS in the welded HSLA was released by machining a U-notch in the WM. A thick BL of 10 mm was found to be beneficial to fatigue resistance when a U-notch was in the PM.

Abstract: Fatigue crack growth properties of Bisplate 80, a high strength low alloy (HSLA) steel, with extensive weld repair have been studied. Fatigue cracking becomes relevant if extensive abrasive wear damage is repaired through welding because of the change in material properties. In this study, extended compact tension (E-CT) specimens of Bisplate 80 with and without weld repair, and with and without a buffer layer between the weld and parent material are used to evaluate the fatigue crack growth behaviour. Fatigue crack growth rates are closely monitored at the interface regions between the weld, buffer layer and parent metal. Detailed SEM observations are also conducted at those locations. It is expected that the experimental results can provide useful information on the optimum weld repair conditions of HSLA.