通过外加电流阴极保护下的慢应变速率试验,结合组织观察和电化学极化曲线测试,对比研究了X90钢母材和焊接接头在库尔勒和北京土壤模拟溶液中的氢脆敏感性。结果表明:X90钢母材组织晶粒细小,而焊接接头的熔合线及热影响区粗晶区的晶粒相对粗大;在-0.9,-1.1 V(相对于饱和甘汞电极SCE)阴极保护下,母材在两种土壤模拟溶液中均表现出较低的氢脆敏感性;在同样的阴极保护电位下,X90钢焊接接头的氢脆敏感性明显高于母材,且其在库尔勒土壤模拟溶液中的氢脆敏感性高于在北京土壤模拟溶液中。在阴极保护条件下,材料的组织粗大、不均匀、高强度及土壤环境的高矿化度都会增加材料发生氢脆的风险,其中高矿化度环境是主要因素。

Hydrogen embrittlement susceptibility of base metal and welded joint of X90 steel in Korla and Beijing soil simulation solutions was studied in comparison by slow strain rate test (SSRT) under impressed current cathodic protection, in combination with microstructure observation and electrochemical polarization curve testing. The results show that the X90 steel base metal had fine grains, while the fusion line and coarse-grained zone of the heat-affected zone (HAZ) had relatively coarse grains for the welded joint of X90 steel. Under the cathodic protection at -0.9, -1.1 V (vs. SCE), the base metal showed low hydrogen embrittlement susceptibility in both soil simulation solutions. The hydrogen embrittlement susceptibility of welded joint was significantly higher than that of the base metal at the same cathodic protection potential, and the hydrogen embrittlement sensitivity in the Korla soil simulation solution was higher than that in the Beijing soil simulation solution. Under cathodic protection, the risk of hydrogen embrittlement would be increased by the coarse structure, uneven structure, high strength of materials and the high salinity of soil environment, among which high salinity of soil environment was the main factor.