Palmqvist fracture toughness of a new wear-resistant weld alloy

The Palmqvist fracture toughness method was applied in a new fashion to measure the fracture toughness of a new wear-resistant alloy in both a powder product for plasma-transferred arc (PTA) welding and a wire product for metal inert gas (MIG) welding. Cracks were observed at high loads with a linear relationship between load and crack length indicating that only Palmqvist cracks occurred in the alloys. The fracture toughness for the no-preheat and preheat PT40 welds are 15.6±0.3 Mpa m^1/2 and 17.6±0.1 MPa m^1/2, respectively, and for the no-preheat and preheat MG40 welds are 12±1 MPa m^1/2 and 20.5±0.2 MPa m^1/2, respectively. Observations of the cracks show evidence of ligaments indicating that the toughness mechanism is due to crack bridging. The microstructural scale and morphology correlates with the fracture toughness, and as the structural scale decreases, the fracture toughness increases.