热老化316L不锈钢在模拟核电溶解氧/氢高温高压水中应力腐蚀裂纹扩展行为  

Stress Corrosion Cracking Behavior of Thermally Aged 316L SS in Simulated Oxygenated/Hydrogenated High Temperature and Pressure Water in Nuclear Power Plants

作　　者：吴文博 张志明[1,3] 王俭秋 韩恩厚[1,3] 柯伟 WU Wenbo;ZHANG Zhiming;WANG Jianqiu;HAN Enhou;KE Wei(Key Laboratory of Nuclear Materials and Safety Assessment,Institute of Metal Research,Chinese Academy of Sciences,Shenyang 110016,China;School of Materials Science and Engineering,University of Science and Technology of China,Shenyang 110016,China;Liaoning Key Laboratory for Safety and Assessment Technique of Nuclear Materials,Shenyang 110016,China)

机构地区：[1]中国科学院金属研究所,中国科学院核用材料与安全评价重点实验室,沈阳110016 [2]中国科学技术大学材料科学与工程学院,沈阳110016 [3]辽宁省核电材料安全与评价技术重点实验室,沈阳110016

出　　处：《材料导报》2020年第6期144-150,共7页Materials Reports

基　　金：国家重点研发计划(2017YFB0702100);国家自然科学基金(51771211);中国科学院前沿科学重点研究项目(QYZDY-SSWJSC012);中国科学院重点部署项目(ZDRW-CN-2017-1)~~

摘　　要：利用直流电位降(DCPD)和高温高压腐蚀测试系统,开展了热老化2 000 h的316L不锈钢(SS)样品在320℃、13 MPa的模拟核电-回路含1.5×10-3 B和2.3×10-6 Li的高温高压水中的应力腐蚀裂纹扩展速率(CGR)测试。结果表明,当溶液中的溶解氧(DO)含量从2×10-6逐步降低至10-6、5×10-7、10-7以及5×10-9时,热老化316L SS的CGR逐渐降低,其中DO降低至5×10-7以及更低时,CGR降低明显。当溶液由DO转为溶解氢(DH)时,CGR进一步降低。利用扫描电子显微镜(SEM)以及电子背散射衍射(EBSD),对测试后样品的断口形貌以及裂纹扩展路径进行了观察,断口呈现典型的沿晶应力腐蚀开裂(IGSCC)形貌。DO/DH的改变主要影响了裂纹尖端的传质过程以及裂纹尖端新鲜表面的再钝化过程,进而影响CGR。热老化2 000 h对316L SS的微观结构以及在高温高压水中的应力腐蚀CGR影响较小。The crack growth rate(CGR)of stress corrosion cracking(SCC)of thermally aged 316L stainless steel(SS)for 2000 h in simulated primary high temperature and high pressure water of 1.5×10-3 B and 2.3×10-6 Li at 320℃and 13 MPa is tested using direct current potential drop(DCPD)system and high temperature and high pressure corrosion test system.Results show the CGR of thermally aged 316L SS is decreased gradually with the dissolved oxygen(DO)content in the solution decreasing from 2×10-6 to 10-6,5×10-7,10-7 and 5×10-9.When the DO content decreasing from 5×10-7 to the lower,the CGR of SCC is decreased significantly.The CGR is further decreased,when the solution is changed from DO to dissolved hydrogen(DH).Scanning electron microscopy(SEM)and electron back scattering diffraction(EBSD)are used to observe the fractures and crack propagation paths of the tested specimens.SCC fracture mainly presents a typical characteristic of intergranular stress corrosion cracking(IGSCC).The change of DO/DH mainly affects the mass transfer process of cracks tip and the repassivation process of the bare surface at cracks tip,which further affects the CGR.The thermal aging of 316L SS for 2000 h has a small effect on its microstructure and CGR of SCC in high temperature and high pressure water.

关 键 词：溶解氧/溶解氢 热老化 不锈钢 高温高压水 应力腐蚀开裂 裂纹扩展速率 

分 类 号：TG172.82[金属学及工艺—金属表面处理]