Research on Microstructure and Mechanical Property of S30432 Supreheater Pipe Aged at 700°C

The microstructure and performance of S30432 supreheater pipe were investigated before and after it is aged 3000 h at 700°C. A lot of twins disappeared after aging, M₂₃C₆ particles precipitated along the grain boundary and MX particles precipitated near the dislocation. After the endurance experiment of the aged pipe, M₂₃C₆ precipitations with the size of about 50 nm pinned dislocations and the cavity appeared on the grain boundary. The aged S30432 supreheater pipe showed the ductile fracture. Increasing temperature made the inter‐granular fracture transfer the quasi‐cleavage fracture and the equiaxed morphology change the parabola morphology. The strength of the untreated specimen decreased with the temperature increasing. The hardness and the impact energy of the aged specimen were larger than those of the untreated specimen. Tensile strength and elongation of untreated specimen were larger than that of aged specimen.