模拟深海环境下高强钢焊缝阴极保护研究

目的研究海水中阴极极化电位下高强钢焊缝氢脆断裂的规律,确定合理的阴极保护电位区间。方法通过模拟深海压力环境,采用慢应变速率拉伸试验(SSRT)、电化学测量方法和腐蚀失重试验进行研究,结合电子显微镜对断口形貌进行观察。结果模拟深海4.50 MPa压力环境下,随着阴极保护电位负移,高强钢焊缝保护度逐渐提高,在极化电位为-0.77 V(vs Ag/Ag Cl/海水,下同)时,材料的保护度达到90%。在-0.71~-0.95 V的电位区间内,高强钢焊缝断裂的方式为韧性断裂;在-1.00 V电位下,高强钢焊缝断裂的方式为脆性断裂;在极化电位不超过-0.96 V时,材料的氢脆系数不超过25%。结论高强钢焊缝在深海环境下的合理保护电位区间为-0.77~0.96 V。

Cathodic Protection Research of High-strength Steel Welding Line in Simulated Deep-sea Environment

Objective To study the law of hydrogen embrittlement breaking for high-strength steel welding seam under cathodic polarization in sea water, and determine then a reasonable cathodic protection potential range can be determined. Methods By simulating the deep sea pressure environment, the author used slow strain rate tensile tests (SSRT), electrochemical measurement methods and corrosion weight loss test were adopted to study the law and, combined with the fracture morphology was observed by electron microscopy. Results The conclusions were drawn as follows: aAs cathodic protection potential shifted toward negative, shifting the protection degree of high-strength steel welding seam gradually increased under in simulated deep sea pressure environment at 4.50 MPa. When the polarization potential was applied at applied by -0.77V(vs Ag/AgCl/ sea water , the same below), the protection degree of the material get got to 90%. When it wasWithin at -0.71(Ecorr)~ -0.95 V potential range, high-strength steel welding seam was mainly subjected to ductile fracture. When the potentialit was applied at -1.00V, fracture morphology showed typical hydrogen embrittlement. When the polarization potentialit was positive than the potential of was not over -0.96 V, the hydrogen embrittlement coefficient of the material does did not exceed 25%. Conclusion There by the reasonable protection range of high-strength steel welding seam was determined at -0.77 ~ 0.96 V under deep -sea environment.