高强双相不锈钢活塞杆开裂原因分析  

Crack cause analysis of high strength duplex stainless steel piston rod

作　　者：郑凯 钟振前[1,3] 曹文全 林双平[1,3] 高群[1,3] ZHENG Kai;ZHONG Zhenqian;CAO Wenquan;LIN Shuangping;GAO Qun(NCS Testing Technology Co.,Ltd.,Beijing 100081,China;Institute for Special Steels,Central Iron and Steel Research Institute Co.,Ltd.,Beijing 100081,China;Failure Analysis Center,Centre Iron and Steel Research Institute Co.,Ltd.,Beijing 100081,China)

机构地区：[1]钢研纳克检测技术股份有限公司,北京100081 [2]钢铁研究总院有限公司特殊钢研究院,北京100081 [3]钢铁研究总院失效分析中心,北京100081

出　　处：《冶金分析》2023年第1期88-93,共6页Metallurgical Analysis

摘　　要：一种高强双相不锈钢活塞杆在加工完成后的存放过程中开裂。实验通过金相显微镜、扫描电子显微镜(SEM)、拉伸试验机、冲击试验机、硬度仪等手段,对其开裂原因进行了分析。结果表明:活塞杆横向和纵向强度均较高,纵向抗拉强度最高达1145 MPa;布氏硬度为HBW347,高于设计要求(HBW241-285)上限21.8%;但横向韧性较低,断后伸长率最低2.0%,仅为标准要求下限值14%的14.3%,平均冲击吸收能量只有5.8 J,仅为标准规范下限值60 J的10.5%。活塞杆材料合金元素符合标准要求,活塞杆组织为回火马氏体+细条带状铁素体,但氢含量达5.4×10-6(质量分数),高的氢含量导致在内部形成氢致延迟微裂纹是其纵向开裂的主要原因,条带状铁素体恶化了活塞杆的横向力学性能,对开裂起一定的促进作用。建议优化冶炼和热加工工艺,与此同时在活塞杆加工之前增加去氢退火,降低原材料中氢含量,以最大程度降低氢致延迟开裂倾向。The cracking of one high strength duplex stainless steel piston rod occurred during storage.The causes were analyzed in experiments by the means of metallographic microscope,scanning electron microscope(SEM),tensile testing machine,impact testing machine and hardness tester.The results showed that both transverse and longitudinal strength of piston rod was high.The maximum longitudinal tensile strength was up to 1145 MPa.The Brinell hardness was HBW347,which was 21.8%higher than the upper limit of design requirement(HBW241-285).However,the transverse toughness was relatively low.The lowest percentage elongation after fracture was only 2.0%,which was only 14.3%of the lower limit of standard requirement(i.e.,14%).The average impact absorbed energy was only 5.8 J,which was 10.5%of the lower limit specified in the standard(i.e.,60 J).The alloying elements in piston rod material met the standard requirement.The structure was tempered martensite+thin strip ferrite.But the content of hydrogen was up to 5.4×10-6(mass fraction).High hydrogen content caused hydrogen induced delay microcrack internally,which was the main reason to cause longitudinal cracking.The stripped ferrite deteriorated the transverse mechanical property of piston rod,which had certain promoting effect on the cracking.It was suggested to optimize the smelting and heat treatment process.Meanwhile,the dehydrogenization annealing should be also added before processing of piston rod to reduce the hydrogen content in raw material,thus to reduce the tendency of hydrogen induced delay cracking at the greatest extent.

关 键 词：高强双相不锈钢 活塞杆 回火马氏体/铁素体 氢脆 不锈钢 韧性 

分 类 号：TF[冶金工程]