X90管线钢焊接接头氢致开裂敏感性研究  

Investigation of Hydrogen-induced Cracking Susceptibility of X90 Pipeline Steel Welded Joints

作　　者：严春妍[1] 周倩雯 张浩[1] 姜心怡 易思 张可召 YAN Chunyan;ZHOU Qianwen;ZHANG Hao;JIANG Xinyi;YI Si;ZHANG Kezhao(College of Mechanical and Electrical Engineering,Hohai University,Changzhou 213022;School of Materials Science and Engineering,Zhejiang University,Hangzhou 310013)

机构地区：[1]河海大学机电工程学院,常州213022 [2]浙江大学材料科学与工程学院,杭州310013

出　　处：《机械工程学报》2023年第24期83-94,共12页Journal of Mechanical Engineering

基　　金：国家自然科学基金(51804097);江苏省科研与实践创新计划(B200203154)资助项目。

摘　　要：X90管线钢在石油天然气管道中具有广泛应用前景,其焊接接头在服役过程中存在氢致开裂(Hydrogen induced cracking,HIC)倾向。采用电化学氢渗透试验和预充氢慢应变速率拉伸试验(Slow strain rate tensile test,SSRT),对X90管线钢焊接接头的氢捕获效率和氢致开裂敏感性进行了研究。利用场发射扫描电子显微镜(Field emission scanning electronic microscope,FE-SEM)对试样断口形貌及裂纹处夹杂物进行观察和分析,采用氢微印技术(Hydrogen microprint technique,HMT)对显微组织中氢的局部分布和聚集进行分析。结果表明,不同充氢电流密度下,X90管线钢焊接接头SSRT试样的断裂位置均为焊缝,其氢致开裂敏感性明显高于母材。与X90管线钢母材相比,焊缝中氢扩散系数较小,氢浓度、可逆和不可逆氢陷阱密度均较高。焊缝中的针状铁素体、贝氏体组织晶界及其亚晶界和夹杂均是有效的氢捕获陷阱,具有较高的氢捕获效率;焊缝中尺寸大于2μm夹杂物的数量多于母材,氢致裂纹易在富Al、富S、富Si夹杂和金属基体的界面处产生。X90 pipeline steel has extensive application prospects in the construction of oil and gas pipelines,but its welded joint is sensitive to hydrogen induced crack(HIC)in the service process.The hydrogen trapping efficiency and HIC susceptibility of X90 pipeline steel welded joint were investigated using the electrochemical hydrogen permeation test and the hydrogen pre-charged slow strain rate tensile test(SSRT).Fracture morphology and the inclusions in the cracked area were observed and analyzed using field emission scanning electronic microscope.Local hydrogen distribution and accumulation in the microstructures were visualized using the hydrogen microprint technique(HMT).The results show that the SSRT specimens of the welded joint fractured in the weld metal under all the charging current densities.The welded joint was more susceptible to HIC than the X90 base metal.The weld metal exhibited smaller effective hydrogen diffusion coefficient Deff,higher hydrogen concentration C0,reversible hydrogen trap sites density Nrand irreversible hydrogen trap sites density Nir than that of X90 base metal.Acicular ferrite(AF),grain boundaries,bainitic lath boundaries and inclusions in the X90 weld metal were effective hydrogen traps inducing high trapping efficiency.The amount of inclusions with the size>2μm in the weld metal is higher than that in the X90 base metal.The interfaces between inclusions enriched in Al,S and Si and the metal matrix were favored sites for HIC nucleation.

关 键 词：X90管线钢 夹杂 显微组织 氢陷阱 

分 类 号：TG172[金属学及工艺—金属表面处理]