高碳奥氏体耐热钢晶间腐蚀行为与纳米化快速脱敏的研究进展  

Research Progress on Intergranular Corrosion Behavior and Rapid Desensitization by Surface Nanocrystallization of High-carbon Austenitic Heat-resistant Steel

作　　者：王锐坤 周晴雯 高岩[3] WANG Rui-kun;ZHOU Qing-wen;GAO Yan(School of Mechanical and Electrical Engineering,Guangzhou University,Guangzhou 510006,China;School of Science,Harbin Institute of Technology(Shenzhen),Shenzhen 518055,China;School of Materials Science and Engineering,South China University of Technology,Guangzhou 510641,China)

机构地区：[1]广州大学机械与电气工程学院,广州510006 [2]哈尔滨工业大学(深圳)理学院,广东深圳518055 [3]华南理工大学材料科学与工程学院,广州510641

出　　处：《表面技术》2022年第3期1-11,50,共12页Surface Technology

基　　金：国家自然科学基金(51471072);广东省基础与应用基础研究基金(2019A1515011683)。

摘　　要：在传统304不锈钢基础上开发的高碳奥氏体耐热钢Super304H具有优异的高温性能,被大量应用于制造超超临界火电机组的过热器管和再热器管,然而其高碳含量带来的高晶间腐蚀敏感性问题已成为影响Super304H钢安全运行的关键因素。为此,研究人员从Super304H奥氏体耐热钢管材的成分优化、热处理工艺改进,特别是脱敏自愈合工艺调控与机理等几个方面进行了研究,寻求降低该材料晶间腐蚀敏感性的方法。在简介奥氏体耐热钢晶间腐蚀机理的基础上,重点综述了近年来Super304H钢晶间腐蚀防护各类对策的研究进展。目前传统的选取C含量下限、添加Nb稳定化元素和双固溶处理等常规手段,都无法有效遏制Super304H钢在高温服役过程中因M_(23)C_(6)的快速形成而引发的高晶间腐蚀敏感性,只能另辟蹊径。通过采用表面喷丸纳米化工艺,不仅加快富铬碳化物M_(23)C_(6)的形成,而且也促进了贫铬区的自愈合,实现了快速脱敏的目标。然而,严重的塑性变形组织在高温时效早期便出现富铬sigma相快速析出的异常现象,导致Super304H钢的腐蚀性能劣化。对此,进一步调节喷丸处理的工艺参数,在避免sigma相析出的前提下获得贫铬区快速脱敏自愈合的最优脱敏工艺,并维持了纳米晶的稳定性,而且所进行的脱敏处理没有对不锈钢的均匀腐蚀性能带来负面影响。最后展望了奥氏体耐热钢晶间腐蚀防护技术在超超临界机组领域的发展方向。The high-carbon austenitic stainless steel Super304H developed on the basis of traditional 304 stainless steel has excellent high-temperature performance and is widely used as superheater and reheater tubes in the ultra supercritical units.However,its high intergranular corrosion sensitivity (IGCS) caused by the high carbon content has become a key issue affecting the safe operation of the ultra supercritical units.Researchers have made a comprehensive studies,like composition optimization,improvement of heat treatment and adjustment of self-healing technics,trying to seek an effective method to reduce the IGCS of Super304H steel.After a brief introduction of the mechanism of intergranular corrosion of austenitic stainless steel,this paper focused on the research progress of various countermeasures for intergranular corrosion protection of Super304H steel in recent years.Conventional methods such as selecting the lower limit of C content,adding Nb stabilizing element and double solution treatment were found to be not able to curb completely the IGCS caused by the formation of M_(23)C_(6)of Super304H steel,so another way has to be explored.Surface nanocrystallization by shot peening (SP) was found to accelerate the formation of M_(23)C_(6)and the healing of chromium depleted zones of Super304H steel,and as a result,rapid desensitization could be obtained.However,severely deformed microstructure by SP triggered the abnormal precipitation of chromium-rich sigma phase during aging,resulting in the deterioration of intergranular corrosion resistance of the steel.Therefore,a critically unsaturated SP process that could avoid the abnormal sigma-phase precipitation was investigated by optimizing the SP technics.The obtained SP process is the optimal one for rapid self-healing and desensitization in the chromium-depleted zones of Super304H steel.Meanwhile,the surface nanocrystalline can keep a good thermal stability and the desensitization treatment does not have a negative impact on the uniform corrosion performance of t

关 键 词：奥氏体耐热钢 晶间腐蚀 表面纳米化 快速脱敏 临界变形量 

分 类 号：TG174[金属学及工艺—金属表面处理]