摘要
对一次汽缸接管封堵堵板泄漏事故进行了分析,通过金属元素化验、金相检验和显微硬度检验等手段对开裂的焊缝接头进行取样检验,推导出焊缝为整圈未焊透结构,焊接工艺执行不到位是焊缝失效开裂的最重要的原因,焊接接头熔合线I型碳化物析出和粗晶区淬硬的马氏体组织对焊接接头造成不利影响,同时机组参与调峰产生交变应力加速了部件的开裂失效。对ZG15Cr2Mo1钢的焊接性使用碳当量法进行了计算,碳当量Ceq为0.85%~1.09%,大于焊接性好的钢种碳当量数值两倍,焊接性较差,需要通过焊前预热,控制层间温度,采用小的线能量来防止裂纹产生。镍基冷焊具备这些特点,但异种钢焊接热膨胀系数不同,不适合用于温差应力过大工况。结合汽缸壁厚大和接管短的结构特点,对焊接工艺进行了重新制定,采用定制中频线圈和红外联合多种加热方式进行焊后热处理,解决了现场热处理难度大的问题。采用圆形堵头和同材质对接焊缝的结构形式重新对接管进行了封堵,成功完成了汽缸泄漏部位的焊接修复。
The leakage accident of a cylinder nozzle plugging plate is analyzed.The cracked weld joint is sampled and inspected by metal element test,metallographic examination and microhardness test.It is deduced that the weld is a whole ring incomplete structure,and the most important reason for the failure and cracking of the weld is that the welding process is not implemented properly,The martensite structure of the fusion line I-type carbide precipitation and coarse grain zone hardening has a negative effect on the welding joint.Meanwhile,the unit participates in peak regulation and produces alternating stress to accelerate the cracking failure of the parts.The weldability of ZG15 Cr2 Mo1 steel is calculated by carbon equivalent method.CEQ is 0.85%~1.09%,which is more than twice the carbon equivalent value of the steel with good weldability,and the weldability is poor.It is necessary to preheat before welding,control the temperature between layers and adopt small line energy to prevent cracks.The cold welding of nickel base has these characteristics,but due to the different thermal expansion coefficient of different steel welding,It is not suitable for the condition of excessive temperature difference stress.Combined with the structural characteristics of large cylinder wall thickness and short nozzle,the welding process is re formulated.The heat treatment after welding is carried out by using customized intermediate frequency coil and infrared heating method.which solves the problem of difficult heat treatment on site.The pipe was re blocked by the structure of circular plug and butt weld of the same material,and the welding repair of the leaking part of the cylinder was successfully completed.
作者
昃刚
巩振泉
杨一盈
董玲
牟法海
Ze Gang;Gong Zhenquan;Yang Yiying;Dong Ling;Mu Fahai(Hebei Jiantou Energy Science and Technology Research Institute Co.,Ltd.,Shijiazhuang 050000,Hebei,China)
出处
《电站辅机》
2022年第2期10-15,24,共7页
Power Station Auxiliary Equipment
关键词
汽缸焊接
镍基焊缝
泄漏分析
同质热焊
焊接工艺
cylinder stator welding
Nickel base weld
Leakage analysis
Homogeneous hot welding
welding technology
