Repair welding of broken gray cast iron pipes instead of applying lock-stitching method

摘要: The aim of this survey is to analyze the influence of shielded metal arc welding and post-weld heat treatment (PWHT) on repairing broken gray cast iron pipes instead of applying lock-stitching method. Although lock-stitching method is effective in repairing the broken pipes, it is very costly. Optical and scanning electron microscopy was conducted to characterize the fusion zone and the interfaces. Micro-hardness measurements and tensile test were applied to the weldments to investigate the effect of PWHT on mechanical properties of the joints. The results show that continuous cracks at the interface of weld metal (WM) and heat-affected zone (HAZ) can form in samples without PWHT because they are not ductile enough to accommodate the stresses during welding. A uniform hardness profile in different regions of the welded joints by applying proper PWHT is observed. PWHT at 700 °C results in a more …