摘要
高Cr(9%~12%,质量分数)马氏体耐热钢因其较高的热导率、较低的热膨胀系数以及优异的高温蠕变强度等优点而被认为是超超临界火电机组关键设备升级改造的主选材料。然而,服役过程中高Cr马氏体耐热钢高温蠕变强度的不断弱化严重影响了其安全可靠性。以往提升高Cr马氏体耐热钢高温蠕变强度的主要手段是通过合金成分优化设计来促进沉淀相弥散析出,但单一析出强化效应对蠕变强度的提升效果非常有限。近年来,位错-沉淀相-界面协同强化效应在提升高Cr马氏体耐热钢高温蠕变性能方面表现出显著效果。其原理是通过形变热处理引入位错来促进多种沉淀相弥散析出,同时通过控制相变来细化板条组织,增强位错、沉淀相及界面3者之间的交互作用,从而实现多类蠕变强化效应的协同提升。本文总结了高Cr马氏体耐热钢的协同强化机制及形变热处理组织调控,从高温蠕变强度提升角度回顾了合金成分的优化历程,阐述了热处理过程中的相变行为及高温组织退化机理,对比分析了单一析出强化效应及形变热处理后位错-沉淀相-界面协同强化效应对其高温蠕变强度的影响规律,并基于焊接接头蠕变失效行为探索了形变热处理对焊接热影响区的组织调控机制,以期为高Cr马氏体耐热钢及其他火电机组用沉淀型强化耐热钢的材料设计及工程应用提供指导。
By virtue of their high thermal conductivity,low thermal expansion coefficient,and excellent high-temperature creep strength,high-Cr(mass fraction:9%-12%)martensitic heat-resistant steels are the putative main constituents of the key equipment in ultra-supercritical(USC)power plants.However,the harsh environment caused by enhancing the steam parameters has recently challenged the hightemperature properties and the continually deteriorating creep strength during service has seriously threatened the safety and reliability of these steels.Previously,the creep strength of high-Cr martensitic heat-resistant steels was enhanced by optimizing the alloying compositions to promote the dispersed precipitation of strengthening phases,but the enhancement effect of reinforced single-precipitate strengthening is limited.In recent years,synergistic strengthening reinforcement of dislocation-precipitate-interface has emerged as a promising solution because the introduced dislocations promote various precipitations and the phase transformation can be controlled to tailor the lath structure,thus reinforcing the dislocationprecipitate-interface interactions and synergistically enhancing various strengthening effects.This paper overviews the synergistic strengthening of dislocation-precipitate-interface and microstructure control in high-Cr martensitic heat-resistant steels subjected to thermo-mechanical treatments.The review covers alloying optimization to improve the creep strength,the phase transformations during heating treatments,and the mechanism of microstructural degradation at high temperatures.It also compares the effects of single-precipitate and synergistic strengthening processes on creep strength and introduces microstructure control in welded joints by thermo-mechanical treatments in terms of creep failure behaviors.This research aims to guide the design and engineering applications of high-Cr martensitic heat-resistant steels and other precipitate-strengthening heat-resistant steels for USC power plants.
作者
张竟文
余黎明
刘晨曦
丁然
刘永长
ZHANG Jingwen;YU Liming;LIU Chenxi;DING Ran;LIU Yongchang(State Key Laboratory of Hydraulic Engineering Simulation and Safety,School of Materials Science and Engineering,Tianjin University,Tianjin 300354,China)
出处
《金属学报》
SCIE
EI
CAS
CSCD
北大核心
2024年第6期713-730,共18页
Acta Metallurgica Sinica
基金
国家自然科学基金项目No.52034004
国家重点研发计划项目No.2022YFB3705300。
关键词
高Cr马氏体耐热钢
高温蠕变强度
协同强化
形变热处理
组织调控
high-Cr martensitic heat-resistant steel
high-temperature creep strength
synergistic strengthening
thermo-mechanical treatment
microstructure control
