【作者】 祖方遒； 刘海明； 余瑾； 王强；

【Author】 ZU Fang-qiu, LIU Hai-ming, YU Jin, WANG Qiang (School of Materials Science and Engineering, Hefei university of technology, Hefei, Anhui 230009)

【机构】 合肥工业大学材料科学与工程学院；

【摘要】 在传统的等温淬火工艺条件下,强(硬)度及塑(韧)性往往不能同时得到很好的兼顾。为了进一步同时提高硬度和韧性,采用了两步法等温淬火热处理工艺,即在低温盐浴保温适当时间后再经高温盐浴保温淬火,使基体先在低温过冷度较大时大量形核,再经高温保温使基体组织具有含量较高的残余奥氏体,细化组织进而提高力学性能。本文先通过在不同低温保温时间下的组织对比,确定较佳的低温盐浴保温时间,然后进行传统的等温淬火和两步法热处理工艺试验。通过两种工艺的结果对比,新的等温淬火工艺(两步法)使铸件得到了较为理想的组织和性能。更多还原

【Abstract】 Because of the traditional austempering (single austempering process) heat treatment process, it can not acquire higher hardness combined with higher toughness. In order to improve the hardness and toughness simultaneously, the heat treatment process of two - step austempering was adopted. At first, the ADI was austempered in lower temperature salt bath. After austenitized for a moment, it was immerged into higher temperature salt bath immediately. So nucleation was acquired easily in condition of higher supercooling and matrix has higher volume fraction of retained austenite after austempering in higher temperature salt bath, it has finer ferrit and austenite and this results in higher properties. In this paper, the optimum austempering time in lower temperature salt bath was determined by comparison of different microstructure with different austempering time. Then the traditional and two - step heat treatment processes were tried out, test results showed that two - step austempering process has resulted in significant improvement in hardness and toughness of the material over the conventional single - step austempering process.更多还原