Prevention of delayed cracking of iron based hardfacing welds

Longitudinal and transverse cracks were observed to occur on the surface of Norem hardfacing welds for a period of time after welding. The welds were mainly cracked by hot cracking. To prevent the weld from cracking, a hammer peening process was employed to mitigate its tensile stress. A scanning electron microscope (SEM), equipped with the electron backscatter diffraction (EBSD) capability, was used to study the phase and carbide distribution in the weld. The results showed that the hammer peening process could help prevent crack propagation by reducing the welding residual stress and inducing a great number of low angle grain boundaries. The microstructures and micro-hardness of the peening-treated welds are also compared to the as-welded specimens in this paper to demonstrate the efficacy of the peening process to prevent weld from cracking.