20Cr32NiNb钢热壁集气管的失效分析

Failure Analysis of 20Cr32NiNb Steel Hot Outlet Manifold

某厂CO转化炉热壁集气管在服役2a后发生早期开裂,通过断口宏观观察、扫描电镜观察、化学成分分析、力学性能测试等对开裂集气管进行了失效分析。结果表明:集气管的失效形式为蠕变开裂;由于集气管长期在高温下服役,大量蠕变孔洞在晶界处萌生,并在高温和应力作用下不断长大,相邻蠕变孔洞间相互连接或融合,形成裂纹,在应力作用下,裂纹沿晶界不断扩展并最终导致集气管的开裂。

The hot outlet manifold of CO reformer used in a factory cracked prematurely after its service for 2 a.The failure analysis of the cracked outlet manifold was performed by macroscopic observation of the fracture,scanning electron microscope observation,chemical composition analysis and mechanical property tests.The results show that the failure type of the outlet manifold was creep cracking.Because the outlet manifold served at high temperature for a long time,creep cavities generated along grain boundaries and grew gradually at high temperature and stress.The adjacent cavities connected or merged together to form cracks.Cracks propagated gradually and finally the outlet manifold cracked under the stress.