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本文通过化学成份、金相组织与断口分析,并进行机械性能、断裂韧度与应力腐蚀倾向测试,结合超高压管的实际运行条件,分析了使用14年的4340钢超高压管的失效原因。结果表明,由于超高压管外壁冷却水中含氧量过高,使管外壁受腐蚀而萌生裂纹,并进一步扩展,最终导致裂纹穿透管壁而引起泄漏失效。对裂纹的扩展,腐蚀疲劳起了主要作用。
Based on the chemical composition, microstructure and fracture analysis, mechanical properties, fracture toughness and stress corrosion propensity test, combined with the actual operating conditions of the ultrahigh pressure pipe, the causes of the failure of the 4340 ultrahigh pressure pipe in 14 years were analyzed. The results show that due to the high oxygen content in the cooling water of the outer high-pressure pipe, the outer wall of the pipe is eroded and then cracked and further expanded, eventually causing the crack to leak through the pipe wall. The crack expansion, corrosion fatigue played a major role.