304不锈钢法兰紧固双头螺柱开裂原因分析  

Failure Analysis on Cracking of 304 Stainless Steel Flange Fastening Double-headed Stud

作　　者：姚添 马卫锋 王贻斌 唐军 任俊杰 王珂 党伟 聂海亮 梁晓斌 YAO Tian;MA Weifeng;WANG Yibin;TANG Jun;REN Junjie;WANG Ke;DANG Wei;NIE Hailiang;LIANG Xiaobin(State Key Laboratory for Performance and Structure Safety of Petroleum Tubular Goods and Equipment Materials,CNPC Tubular Goods Research Institute,Xi′an,Shaanxi 710077,China;Hancheng Branch of PetroChina Coalbed Methane Co.Ltd.,Hancheng,Shaanxi 715400,China;Changqing Oilfield Branch NO.6 Gas Production Plant,Xi′an,Shaanxi 710018,China)

机构地区：[1]中国石油集团工程材料研究院有限公司,石油管材及装备材料服役行为与结构安全国家重点实验室,陕西西安710077 [2]中国石油煤层气有限责任公司韩城分公司,陕西韩城715400 [3]长庆油田分公司第六采气厂,陕西西安710018

出　　处：《石油管材与仪器》2023年第3期71-75,共5页Petroleum Tubular Goods & Instruments

摘　　要：某沿海分输站卧式分离器液位计9根304不锈钢法兰紧固双头螺柱发生了开裂失效。为了确定该批双头螺柱开裂原因,对其进行了裂纹宏观形貌分析、材料化学成分分析、裂纹形貌金相分析、断口形貌扫描电镜分析和断口表面成分能谱分析。结果表明,失效双头螺柱材料的碳元素含量较高,不符合GB/T 3098.6—2014标准的要求。失效双头螺柱材料的晶粒度为3.0~5.0级。失效双头螺柱中的裂纹为沿晶开裂裂纹,且主裂纹附近存在树枝状微裂纹。开裂裂纹表面含有可导致奥氏体不锈钢发生应力腐蚀开裂的氯元素。因此,失效双头螺柱开裂为氯离子导致的应力腐蚀开裂。建议沿海环境条件下应选用双相不锈钢或超纯铁素体不锈钢等材料的双头螺柱。Nine 304 stainless steel flange fastening double-headed studs cracked in the horizontal separator level gauge of a coastal sub-transmission station.In order to clarify the cracking causes,the macroscopic morphological analysis,material chemical composition analysis,metallographic analysis,fracture scanning electron microscopy and energy spectrum analysis were carried out.The results show that the carbon content of the failed double-headed studs is high,which does not meet the requirements of GB/T 3098.6—2014 standard.The grain size grade was in the range of 3.0 to 5.0 with coarse grains.The crack in the failed double-headed studs is along the crystal boundary and there were dendritic microcracks near the main crack.The fractures contain chlorine element that easily induces stress corrosion cracking of austenitic stainless steel.Therefore,the cause of the double-headed stud cracking is stress corrosion cracking triggered by chloride ions.It is recommended that double-headed studs with matreials such as double-phase stainless steel or ultra pure ferroite stainless steel should be used under coastal environment.

关 键 词：304不锈钢 双头螺柱 应力腐蚀开裂 

分 类 号：TE988[石油与天然气工程—石油机械设备]