某Q235钢天然气管道运行10 a后发生了泄漏, 采用表面宏观形貌观察、力学性能测试、金相检验、硬度及残余应力检验等方法分析了管道开裂的原因。结果表明: 管道的开裂为焊接质量存在严重问题而导致的脆性开裂; 焊接残余应力和工作应力、组装应力叠加形成的局部高应力是管道失效的根本原因; 采用适当的焊接工艺、焊后消除应力处理等措施, 可降低管道开裂的几率。

After using for 10 years, a Q235 steel natural gas pipeline leakage occured, the cracking cause was analyzed by macrograph examination, mechanical property testing, microscopic examination and residual stress testing. The results show that the cracking mode was brittle cracking caused by serious welding quality. Localized high stress formed by welding residual stress, work stress and assemble stress was the basic failure cause. Adopting appropriate welding process and eliminating stress after welding could reduce the risk of pipeline cracking.