摘要
利用光学显微镜、扫描电镜及透射电镜对571℃、24.5 MPa条件下服役40 000 h的主蒸汽P91钢管道弯管段和直管段的组织进行了观察,并测试了其力学性能。结果表明,弯管段的硬度、拉伸强度较直管段严重偏低;组织对比发现,弯管段的马氏体组织较直管段发生严重的板条宽化,而且碳化物和亚晶粗化长大,位错密度降低,马氏体转变成铁素体。分析认为,热处理工艺不当导致弯管段出现块状铁素体是导致P91钢管弯管段长期服役后硬度和强度偏低的主要原因。
Microstructure of both the straight and the bending section of main steam P91 steel pipe served under the condition of 571 ℃ and24. 5 MPa for 40 000 h was studied by optical microscope( OM),scanning electron microscope( SEM) and transmission electron microscope( TEM),and corresponding mechanical properties was also tested. The results show that the hardness and the tensile strength of the bending section are much lower than those of the straight section,compared with the martensitic microstructure of the straight section,the microstructure of the bending section is characteristic of martensitic lath widening,subgrains and carbides coarsening as well as transformed ferrite with low dislocation density. It is analyzed that the blocky ferrite produced by improper heat treatment is mainly responsible for lower hardness and strength in the bending section after long-term service.
出处
《金属热处理》
CAS
CSCD
北大核心
2015年第6期54-60,共7页
Heat Treatment of Metals
基金
南方电网公司科技项目(K-GD2014-162)
关键词
P91钢管
长时服役
显微组织
力学性能
P91 steel pipe
long term service
microstructure
mechanical properties
