新型耐热钢的高温低周疲劳性能

研究了新型锅炉用耐热钢ＨＣＭ２Ｓ钢和Ｐ９１钢的高温低周疲劳性能．结果表明，ＨＣＭ２Ｓ钢和Ｐ９１钢均为循环软化材料．通过ＴＥＭ分析发现：ＨＣＭ２Ｓ钢的循环软化与富碳小岛中的马氏体板条回复、稳定位错胞的形成和Ｍ６Ｃ的生成有关，Ｐ９１钢的循环软化则与位错密度降低、位错重新分布引起的强化作用减弱有关，而Ｍ２３Ｃ６粗化只是Ｐ９１钢初始软化后，其强度不断降低的一个原因．同时，还给出了ＨＣＭ２Ｓ钢和Ｐ９１钢的应变－寿命方程

Low Cycle Fatigue Behavior of Heat Resistant Steels at High Temperature

Low cycle behavior is investigated for two types of heat resistant steels HCM2S and P91 at high temperature. They exhibited rapid initial cyclic softening followed by gradual softening until macroscopic crack growth occurred. The initial softening of HCM2S steel was due to the recovery of martensite laths in carbon rich islands, resulting in the formation of stable dislocation cells and M 6C particles. The initial softening of P91 steel was attributed to a combination annihilation and rearrangement. The gradual loss of strength followed by initial softening was associated with the coarsening of M 23 C 6 Phase. Fatigue life equations for HCM2S and P91 as a function of strain range are also presented.