Study on the high temperature creep deformation and fracture behaviors of Inconel 625 deposited metal

The creep behaviors of as-welded Inconel 625 deposited metal were studied over broad ranges of temperature (600 °C–900 °C) and stress (50 MPa–500 MPa), and the corresponding deformation mechanisms and fracture behaviors after rupture were investigated by various techniques. The results showed that the average slope of the creep life and the stress fitting curve was −0.159 (600 °C–800 °C), which was almost the same as that of the cast 625 alloy (−0.16). However, the slope decreased at 900 °C. According to transmission electron microscopy (TEM) observations, the dominant creep deformation mechanism transformed from shearing and climbing of dislocations at 600 °C, 700 °C and 800 °C/200 MPa to cross-slip of dislocations at 800 °C/80 MPa and 900 °C. The fracture behaviors were characterized by optical microscopy (OM) and scanning electron microscopy (SEM). With increasing temperature, the fracture behavior changed from mixed to intergranular. Similarly, the fracture behavior changed with increasing applied stress at 800 °C. At 600 °C, 700 °C and 800 °C/200 MPa, the carbides and intermetallic compounds produced microcracks, which eventually led to fractures. However, at 900 °C and 800 °C/80 MPa, the aggregation of micropores was the main cause of grain boundary failure.