Effect of the microstructure on the tribological properties of HIPed and PTA-welded Fe-based hardfacing alloy

This work focuses on the comparison of the tribological properties of Norem02, a Fe-based hardfacing elaborated by hot isostatic pressing (HIP), a pressure-assisted sintering technique and by plasma transferred arc welding (PTAW), a more conventional coating process. The influence of the microstructural modifications induced by the elaboration process is investigated. The aim of the present study is to assess the possibility of considering HIP as an effective alternative to more conventional hardfacing techniques. Wear tests were carried out using a pin-ondisk tribometer with ball-on-plate configuration under loads of 2, 5 and 10 N against a WC-Co ball counterpart. The worn tracks present typical marks of abrasive wear followed by oxidative but also adhesive ones. HIPed sample presents a dominance of oxidative and adhesive wear, while for sample elaborated by PTAW the dominant mechanism is abrasive wear. The results indicate that in the case of the HIPed alloy the wear resistance is generally increased and under a load of 10 N the wear rate of the HIPed Norem02 is reduced of about 5.5 times. The fine microstructure obtained by HIP, containing small globular carbides well dispersed in the matrix allows the alloy to better withstand the mechanical stresses occurring during the wear tests, reducing the surface damages.