650℃时效Super 304H耐热钢的显微结构与高温拉伸性能  

Microstructure and high-temperature tensile properties of Super 304H heat-resistant steel after ageing at 650℃

作　　者：陈国宏[1] 潘家栋[2] 刘俊建[1] 王家庆[1] 白小龙[2] 张建华[2] 张涛[1] 汤文明[2] 

机构地区：[1]安徽省电力科学研究院,安徽合肥230601 [2]合肥工业大学材料科学与工程学院,安徽合肥230009

出　　处：《材料热处理学报》2013年第5期103-109,共7页Transactions of Materials and Heat Treatment

基　　金：安徽省电力科学研究院技术开发基金(103-413426)

摘　　要：研究了650℃不同时间时效Super 304H钢的显微组织及高温拉伸力学性能特征,探讨其高温拉伸断裂机制。结果表明:高温时效Super 304H钢中析出ε富铜相、Nb(C,N)和M7C3等析出相颗粒。时效初期,M7C3相优先在晶界析出,Super 304H高温强度显著提高,但塑性快速下降。在时效300～500 h时,由于M7C3相逐渐粗化,其高温强度及塑性下降较快。继续时效导致细小ε富铜相和Nb(C,N)相在奥氏体晶内持续析出、弥散分布,其高温强度及塑性逐渐稳定。时效态Super 304H钢高温拉伸断裂呈剪切断特征。采用应力三轴度理论解释了650℃时效Super 304H钢的高温拉伸变形行为及拉伸断裂机制。Microstructure and high-temperature tensile mechanical properties of Super 304H steel after ageing at 650 ℃ for different time were studied, and high-temperature tensile fracture mechanism of the aged steel was also investigated. The results show that the particles, such as Cu-rieh e-phase, Nb （C, N） and M7 C3 cacbides, are precipitated during ageing. In the initial ageing stage, M7 C3 carbide particles preferentially distribute along austenite grain boundaries, leading to the increase of l＇iigh-temperature strength and the decrease of high-temperature plasticity. During ageing for time from 300 h to 500 h, the M7 C3 particles gradually coarsen, leading to the decrease of both high temperature strength and plasticity of the steel. As increasing the ageing time, the continuous precipitation and dispersive distribution of the Cu-rich e-phase and Nb（C, N） particles inside austenite grains inhibits the decrease of the high-temperature strength and plasticity, so the high-temperature mechanical properties of the steel gradually turn to be stable. High-temperature tensile fracture of the Super 304H steel aged at 650 ℃ is in a shearing fracture mode, which is explained in terms of a stress triaxiality theory.

关 键 词：Super 304H耐热钢 高温时效 显微组织 高温力学性能 应力三轴度 

分 类 号：TG142.73[一般工业技术—材料科学与工程]