METHOD OF MAKING LARGE-SIZED AUSTENITIC STAINLESS FORGED STEEL

摘要

PURPOSE: To realize to make the structure of the titled large-sized forged steel esp. having large thickness fine-grained without impeding the complete solid solution of the secondary phases and Cr carbide, by heat-treating the steel after being hot-forged for solution heat treatment, while omitting cooling it to a low temp., mechanical working and reheating, and then toughening it in water. ;CONSTITUTION: After steel is finally finish hot-forged, it is heated and held at 900W1,080°C for solution heat treatment without cooling it below 850°C, and then toughened in water. Accordingly, the precipitation of the secondary phases, e.g. sigma and δ ferrite phases, and Cr carbide after the hot-forging is very little, since the steel is not affected by thermal hysteresis such as cooling and reheating after the hot-forging. As a result, the heat treatment for solid solution after the hot-forging can be executed at a relatively low temp. suited to the formation of fine-grained structure laying emphasis rather on making the fine-grained structure rather than on the solid-solution heat treatment of the secondary phases and Cr carbide.;COPYRIGHT: (C)1983,JPO&Japio