摘要
利用慢应变速率拉伸试验研究了应变速率对X80管线钢在土壤模拟溶液中的应力腐蚀的影响。采用的模拟溶液以我国西北部碱性土壤的化学成分为基础,在不同应变速率条件下进行试验。样品断裂后利用扫描电镜对断口形貌以及断口侧面二次裂纹进行观察。研究结果表明:X80钢在1.0×10-6s-1应变速率下表现出最高的应力腐蚀敏感性。低于该应变速率下,应力腐蚀敏感性略有降低;而高于该应变速率下,应力腐蚀敏感性明显减小。不同应变速率下应力腐蚀敏感性的差异主要是由应力腐蚀过程中腐蚀和力学作用的影响程度不同造成。应变速率低于1.0×10-6s-1时,腐蚀作用影响更大,较长的腐蚀时间造成裂纹被腐蚀,裂纹扩展受到影响,因此应力腐蚀敏感性略有降低。当应变速率高于1.0×10-6s-1时,力学作用主导整个过程,形成的裂纹没有受到足够腐蚀的情况下,在力学作用下发生快速机械扩展、断裂,因此产生了明显降低的应力腐蚀行为。
Stress corrosion cracking susceptibility of X80 pipeline steel was investigated in a simulated soil solution using slow strain rate tensile （SSRT） tests. The simulated soil solution was based on the chemical compositions of alkaline Gansu soil in northwest of China. The tests were conducted at dif- ferent strain rates. The fracture surfaces and secondary cracks were observed using scanning electron microscopy （SEM）. The results showed that strain rates had an important role on SCC of X80 steel in simulated soil solutions. Corrosion and mechanical factors have different influences during the SCC processes at different strain rates, which results in the variety of SCC. There was the highest SCC susceptibility at the strain rate of 1.0×10^-6s^-1. Combined effect of corrosion and mechanics leads to high SCC susceptibility. When the strain rates were lower than 1.0 ×10^-6s^-, enough long corrosion time results in the corrosion of crack in this strain rate range. The crack propagation is restrained. Thus, slight decrease of SCC susceptibilities occurs. As the strain rates were higher than 1.0 ×10^-6s^-, SCC susceptibilities were low obviously. In this high strain rates range, the mechanical factors have more effect on SCC than corrosion factors, which mainly lead to mechanical fracture of speci-mens.
出处
《材料工程》
EI
CAS
CSCD
北大核心
2013年第3期77-82,共6页
Journal of Materials Engineering
基金
中国石油天然气股份有限公司科学研究与技术开发项目(2009110031001035)
