2018 Volume 58 Issue 4 Pages 169-176
Alloy 625 has been used as a structural material for monopropellant thruster of artificial satellite, because Alloy 625 has good nitriding resistance and low cost than those of L-605 alloy as a conventional material for satellite use. The microstructural observation and investigation of tensile properties of alloy 625 before and after aging at 1173 K in N2 gas were conducted in order to evaluate the durability after using as a structural material of artificial satellite. Formation of a thin compound layer which consist of chromium nitride was observed on the surface of alloy 625 after aging at 1173 K in N2 gas. Precipitation of δ-phase (Ni3Nb) and carbides were detected at a grain boundary in aged alloy 625. Tensile strength and fracture elongation obtained in alloy 625 after aged at 1173 K for 1036.8 ks in N2 gas were 952 MPa and 36%, respectively. Fully satisfied tensile properties were maintained in alloy 625 after aged at 1173 K for 1036.8 ks in N2 gas, comparing with those of L-605 alloy.
