25Cr12Ni5Mo钢热疲劳损伤特性研究

Study on thermal fatigue damage characteristics of 25Cr12Ni5Mo steel

采用自约束热疲劳试验方法研究了热处理工艺(1#、2#、3#)对25Cr12Ni5Mo钢热疲劳损伤性能影响。结果表明,随着循环周次的增加平均损伤因子以指数规律增长,三种热处理制度获得的试样平均损伤因子由大到小依次为3#、2#、1#。表面微裂纹取向研究表明,裂纹首先产生在试样的棱角处,然后沿径向和高度方向扩展,在1000周次以内三种试样上均没有明显的主裂纹,众多短小的微裂纹排列成有序的"台阶"状,大于循环周次1000时,"台阶"随着循环周次的增加"搭接"在一起逐步发展成主裂纹。

With the self-restricting test method, the influence of heat treatment conditions on thermal tatigue damage charactensucs of 25Cr12Ni5Mo steel was investigated. The results indicate that the mean damage parameter has an exponential relationship with the increase in number of thermal cycles. The sequence of the mean damage parameters is 3#〉2#〉1#. Tropism of Surface microcracks shows that microcracks initially emerge at the specimen edges and comers, which expand along radial and height. Main cracks were not observed on all of specimen surface before 1000 cycles, a lot of step-like microcracks forms regularly, these ＂steps＂ then join together into main cracks with number of thermal cycle longer than 1000 cycles.