摘要
研究了AL6XN超级奥氏体钢在650-750℃和120-220 MPa应力水平下的高温蠕变特性,以及300和600℃不同恒应变幅值条件下的疲劳特性。结果表明,AL6XN具有优越的高温蠕变抗力,其蠕变激活能Q为327 kJ/mol,蠕变应力指数为5.23。结合变形微结构观察结果表明,AL6XN的蠕变机制为位错攀移和滑移机制。在一定应变量下,AL6XN在600℃时疲劳试验的应力水平高于300℃的应力水平,同时随着应变量的增加和温度的升高,其疲劳寿命显著降低;600℃疲劳试验后仅形成位错缠结,疲劳裂纹扩展断口存在典型的疲劳辉纹,无明显二次裂纹。以上结果表明,AL6XN疲劳裂纹扩展行为与其动态应变时效有关。
High-temperature creep and fatigue behaviors of AL6XN super austenite steel were studied at 650-750 ℃ and 120-220 MPa, and 300 ℃ and 600 ℃ with different strain amplitudes, respectively. The results show that the values of stress exponent and Q for high-temperature creep are estimated to be 5.23 and 327 kJ/mol, respectively. Based on TEM observations, the mechanism of creep was considered as the dislocation climb and glide mode. The stress level of AL6XN steel in the fatigue-test at 600 ℃ is larger than that at 300 ℃, and the cycling life decreases obviously with increasing temperature and strain amplitude. TEM observations revealed dislocation tangles, rather than dislocation cells in the steel after the fatigue-test at 600 ℃, and the typical stria- tions on the fracture surfaces without the secondary cracks are observed by SEM, which is related to the dynamic strain aging occurred in the AL6XN austenitic steel.
出处
《原子能科学技术》
EI
CAS
CSCD
北大核心
2009年第6期509-513,共5页
Atomic Energy Science and Technology
基金
国家重点基础研究发展计划资助项目(2007CB209803)
