摘要
某炼厂S-Zorb装置进料换热器一根管箱法兰螺栓发生断裂。为了解螺栓失效和断裂产生原因,以便制定有效防护措施,避免影响正常生产和确保设备运行安全,采用宏观检验、材质分析、力学性能检测、金相组织分析、扫描电镜及元素能谱分析对断裂原因进行深入探究。结果显示,断裂螺栓表面微观呈现准解理形貌。由此判断,螺栓断裂原因为:因热处理不充分导致微观金相组织晶粒粗大且分布不均,长期使用后合金成分发生偏析,使得基材硬度和冲击韧性变差,再加上断裂部位长期处于应力集中区,产生了疲劳裂纹,在拉应力和扭矩作用下,发生了脆性断裂。基于上述分析结论,建议对螺栓进行恢复性能热处理,并选用合适的热处理工艺细化组织晶粒,从而提高材质的机械性能。
A bolt on the channel head flange of the feed heat exchanger in an S-Zorb unit fractured at a refinery.To identify the cause of the bolt failure and fracture,thereby formulating effective protective measures to prevent disruption to normal production and ensure operational safety of the equipment,an in-depth investigation was conducted through macroscopic inspection,material composition analysis,mechanical property testing,metallographic examination,scanning electron microscopy(SEM),and energy-dispersive X-ray spectroscopy(EDS)analysis.The results indicate that the fracture surface of the bolt presents a quasi-cleavage morphology.It is therefore concluded that the bolt fracture occurred due to the following causes:insufficient heat treatment led to a coarse and unevenly distributed grain structure in the metallographic microstructure.After prolonged ser-vice,component segregation occurred within the alloy,which resulted in reduced hardness and impact toughness of the base material.In addition,prolonged exposure to stress concentration in the fracture region resulted in fatigue crack initiation.Under the action of tensile stress and torque,brittle fracture occurred.Based on the above analytical findings,restorative heat treatment should be implemented for the bolts,specifying appropriate thermal processes to refine the grain structure,thereby improving the mechanical properties of the material.
作者
于慧文
刘希武
包振宇
李辉
Yu Huiwen;Liu Xiwu;Bao Zhenyu;Li Hui(SINOPEC Engineering Group Luoyang R&D Center of Technology,Luoyang,Henan,471003)
出处
《石油化工设备技术》
2025年第4期1-6,I0001,共7页
Petrochemical Equipment Technology
基金
中国石油化工股份有限公司(批准号:CLY23026)资助的课题。
关键词
25Cr2MoVA
螺栓断裂
力学性能
金相组织
热处理
25Cr2MoVA steel
fracture failure of bolts
mechanical properties
metallographic microstructure
heat treatment
