摘要
研究了自行设计的高强钢 30CrMnSi2NiNb在稍高于Ms点温度经不同等温时间处理后的组织和力学性能。结果发现 ,随等温时间的延长 ,强度和硬度先下降后稍有上升 ,塑性和耐延迟断裂性能则先升高后稍有降低。当等温时间为 30～ 6 0min时 ,强度和硬度为最低而塑性和耐延迟断裂性能达到最高 ,此时抗拉强度约为 15 0 0MPa ,KISCC值约为 2 5MPa·m1/ 2 。组织观察和分析表明 ,随等温时间的延长 ,贝氏体转变趋于完全 ,贝氏体含量增加 ,马氏体含量降低 ,残留奥氏体含量先增加而后降低。可见 ,通过选择合适的等温工艺 ,可以使 30CrMnSi2NiNb钢中的残留奥氏体含量增加 。
The high strength steel 30CrMnSi2NiNb was developed by ourself.The microstructures and mechanical properties of this steel were investigated after isothermal quenching for different isothermal holding time.It was found that with increase of isothermal holding time,the strength and hardness is decreased firstly and then slightly increased,whereas the plasticity and delayed fracture resistance are increased firstly and then slightly decreased,showing an opposite trend with that of strength and hardness.For an isothermal holding time of about 30～60min,the strength and hardness are at the minimum values and the plasticity and delayed fracture resistance are reached the maximum values.The minimum ultimate tensile strength is nearly 1500MPa,and the maximum K ISCC value is about 25MPa·m 1/2 .Microstructure observation showed that the microstructure of isothermally quenched steel 30CrMnSi2NiNb is composed of bainite,martensite and retained austenite,the volume fraction of which changed in a similar trend with plasticity with the increase of isothermal holding time.Therefore,the delayed fracture resistance of steel 30CrMnSi2NiNb could be improved by selecting sutiable isothermal processing parameters resulting in an improvement in the fraction of retained austenite.
出处
《金属热处理》
CAS
CSCD
北大核心
2002年第2期12-16,共5页
Heat Treatment of Metals
基金
973国家重大基础研究项目 (G1 9980 61 50 3)
关键词
高强钢
等温时间
复相组织
延迟断裂
力学性能
high strength steel
isothermal holding time
mixed microstructure
delayed fracture
