摘要
某75 t/h燃煤锅炉主蒸汽管道主汽阀门在现场检验过程中,发现阀体腹部位置存在一区域硬度值超标现象,且该区域硬度值明显高于阀体其他部位。通过对该区域进行宏观检查、磁粉检测、化学成分分析、金相组织检验和硬度检验,根据试验结果得出该主汽阀阀体硬度值异常区域应为补焊区域,该区域产生的主要原因应是阀门在成型及热处理后进行了局部挖补处理,挖补后对该部位进行打磨,与基体表面平齐,但挖补后未对该区域进行消应力热处理,造成该区域硬度值超标。焊补区域存在较大的残余应力及界面应力的作用下回火脆性更加敏感,运行中在自重载荷和振动载荷作用下,极易在界面部位诱发微裂纹的生成及扩展,从而导致阀门的泄漏失效。根据试验结果给出相应的建议,并为检验人员提供一种在线检测阀门补焊的方法。
During the field inspection of the main steam valve of the main steam pipe of a 75t/h coal-fired boiler,it is found that the hardness value of an area at the valve body abdomen exceeds the standard,and the hardness value of this region is significantly higher than that of other parts of the valve body.Through macroscopic inspection,magnetic particle inspection,chemical composition analysis,metallographic examination and hardness test are studied of this area,according to the test results,it is concluded that the area with abnormal hardness value of the main steam valve body should be a repair welding area.The main reasons for this area are that the valve has been locally patched after forming and heat treatment.After patching,the part should be polished to be flush with the substrate surface,However,after patching,heat treatment was not carried out to release stress in this area,which caused the hardness value of this area to exceed the standard.The tempering brittleness is more sensitive under the action of large residual stress and interface stress in the weld repair area.Under the action of weight and vibration during operation,it is very easy to induce and propagate microcracks at the interface,leading to the leakage failure of the valve.The corresponding suggestions are given according to the test results,and an online inspection method for valve repair welding is provided for inspectors.
作者
周公文
田裕
焦红军
李强
Zhou Gongwen;Tian Yu;Jiao Hongjun;Li Qiang(Taian Special Equipment Inspection Institute,Taian,Shandong 271001,China)
出处
《机电工程技术》
2023年第9期234-237,共4页
Mechanical & Electrical Engineering Technology
关键词
主汽阀阀体
组织异常
补焊
硬度超标
界面应力
main steam valve body
abnormal organization
repair welding
excessive hard
