Investigation of Austenite Reversion During Aging of 10-Nickel Modified Steel.

摘要

The formation of retained austenite in 10-Nickel Modified Steel has been investigated at various aging combinations of temperature and time over the range 900to 1200F and 0.5to 12.0hours. X-ray diffractometry analysis,using Mo (K sub alpha) radiation,was used to obtain data for the retained austenite measurements. Hardness data were used to correlate retained austenite with mechanical properties. Electron microscopic examination was conducted on specially-aged samples having a large grain size. The formation of retained austenite exhibited an Arhennius-type dependence on aging temperature and grain-boundary diffusion. Secondary hardening occurs for aging times less than one hour and aging temperatures less than 950F. Overaging occurs at longer times and higher temperatures. As aging times increase for aging temperatures below 1100F,the amount of retained austenite increases while the hardness decreases;however,above 1100F both the amount of retained austenite and hardness decrease. When heat treating at 1500F,an equilibrium grain size number of 2is at 100hours. As the actual grain size increased,both the amount of retained austenite and the hardness decreased.