摘要
采用光学显微镜(OM)、能谱仪(EDS)、X射线衍射仪(XRD)、高温显微镜原位观察等实验手段,分析了ZG40Cr25Ni20奥氏体耐热钢烧损原因。结果表明,随着温度升高,奥氏体晶粒不断长大,碳化物Cr23C6不断形成和长大,碳化物中的Cr含量和碳化物硬度不断增加,奥氏体基体中的Cr含量不断减少。温度过高,碳化物溶解,形成孔洞,促进微裂纹沿晶界的扩展,奥氏体晶粒间的结合力逐渐减弱,基体发生过烧,钢的结晶组织遭到破坏,失去金属原有的塑性和强度,造成高温耐热管失效,孔洞和微裂纹的形成及扩展是材料失效的主要原因。此外,高温显微镜原位观察和热处理实验结果表明,ZG40Cr25Ni20耐热钢中碳化物的溶解温度为1030~1250℃。高温显微镜原位观察为碳化物溶解观察和耐热钢失效分析提供了一种新的方法。
Mechanism of burning loss of ZG40Cr25Ni20 austenitic heat-resistant steel was investigated by optical microscope （OM）, energy dispersive spectrometer （EDS） analysis, X-ray diffractioin （XRD） and in situ observation on laser scanning confocal microscopy （LSCM）. The results show that with the temperature increasing, austenite grain grows up, Cr23 C6 carbide forms and grows up and Cr content and microhardness of the carbides increase, whereas Cr content in austenite decreases. When the temperature is too high, carbides dissolve and holes form, which promotes the propagation of micro cracks along the grain boundaries, so the adhesion of the austenite grains gradually loses and overbnrning occurs in the matrix, which degrades the micro-structure and decreases the plasticity and strength of the steel. The formation and expansion of the holes and micro-cracks are responsible for the failure. In addition, in situ observation on LSCM and heat treatment experiments indicate that the dissolution temperature for the carbides in the experimental steel is 1030-1250 ℃. In situ observation on LSCM provides a new method for the behavior of carbide dissolution and failure analysis of heat-resistant steel.
作者
梁伟成
徐光
戴方钦
巫嘉谋
胡海江
LIANG Wei-cheng XU Guang DAI Fang-qin WU Jia-mou HU Hai-jiang(The State Key Laboratory of Refractories and Metallurgy, Wuhan University of Science and Technology, Wuhan 430081, China Hubei Collaborative Innovation Center for Advanced Steels, Wuhan 430081, China I-Iuangshi Sunny Totem Thermal Equipment Co Ltd, I-Iuangshi 435003, China)
出处
《材料热处理学报》
EI
CAS
CSCD
北大核心
2017年第2期77-82,共6页
Transactions of Materials and Heat Treatment
基金
国家高技术研究发展计划("863"计划)项目(2012AA03A504)
关键词
奥氏体耐热钢
碳化物
孔洞
裂纹
失效
austenitic heat-resistant steel
carbide
hole
crack
failure
