广州某石化厂重催装置安全阀弹簧发生了多处断裂，致使整套装置非计划停机。采用宏观检查、化学成分分析、硬度测试、金相检验、断口扫描电镜及能谱分析等方法，对弹簧断裂原因进行了分析。结果表明：弹簧表面长时间暴露在湿H₂S环境中，加之弹簧断裂区显微组织为硬而脆的马氏体，弹簧工作过程中受到较高的剪切应力；三者共同作用，使弹簧于表面偏析和夹杂物区域萌生应力腐蚀裂纹，裂纹不断扩展最终导致弹簧断裂失效。

The safety valve spring of a heavy oil catalysis cracking unit in a Guangzhou petrochemical plant fractured in several places, which caused the entire unit to be stopped unplanned. The fracture causes of the spring were analyzed by macroscopic inspection, chemical composition analysis, hardness test, metallographic examination, and fracture scanning electron microscope and energy spectrum analysis. The results show that the spring surface was exposed to the wet H₂S environment for a long time, the microstructure of the spring fracture zone was hard and brittle martensite, and the spring was subjected to high shear stress during the working process. Under the joint action of above three factors, stress corrosion cracks originated on the spring surface at the segregation and inclusion area. The cracks continued to expand and eventually led to fracture failure of the spring.