摘要
利用三维原子探针(3DAP)研究了超超临界电站锅炉过热器/再热器管材Super304H在650℃时效富Cu相的析出行为.结果表明,富Cu相的析出经历了富Cu原子偏聚区的快速形成以及Cu原子不断聚集到富Cu偏聚区中而渐变形成富Cu相.富Cu相的析出速率极快,时效仅5 h富Cu相已明显析出.随时效时间的延长在富Cu相中逐步排斥出其它元素,使Cu原子成为富Cu相的主要组成元素.时效500 h富Cu相中Cu原子的浓度已经达到90%,时效1000 h富Cu相仍然保持纳米级的尺度且均匀分布,对Super304H耐热不锈钢具有非常好的强化作用.
Super304H austenitic heat resistant steel is based on 18/8 Cr-Ni stainless steel alloyed mainly with 3%Cu and a small amount of Nb combined with N,which is used as superheater/reheater tubes in ultra-super critical（USC） power plants all over the world,due to its good combination of elevated temperature strength with hot corrosion resistance.The excellent high temperature strengths of this steel are mainly contributed by the precipitation strengthening effect of fine Cu-rich phase.Comprehensive study of the characteristic of Cu-rich phase is very important to understand strengthening effect on this steel.However,the Cu-rich phase is very fine and difficult to be detected at the beginning of precipitation.In this paper,three dimensional atom probe（3DAP） was used to study the early stage of precipitation behavior and the composition change in Cu-rich phase of Super304H aged at 650℃for different times after solution treatment at high temperature.Cu-rich phase is formed from Cu-rich segregated rigion by the concentration of Cu atoms in it at very beginning stage of aging.Homogeneously distributed Cu-rich phase precipitates with about 1 nm radius are obviously detected after aging at 650℃for 5 h.With increasing aging time,Cu-rich phase is growing slowly while other elements in the Cu-rich phase decreased obviously.The copper element has almost concentrated to 90%in the center part of Cu-rich phase after 500 h aging.The homogenous distribution of fine Cu-rich phase in austenitic matrix effects excellent hardening with increasing aging time.The stability of fine Cu-rich phase is one of the most important reasons for keeping good strength of Super304H heat resistant steel at high temperature.
出处
《金属学报》
SCIE
EI
CAS
CSCD
北大核心
2010年第9期1141-1146,共6页
Acta Metallurgica Sinica
基金
国家自然科学基金重点资助项目50931003~~
