B^+级(ZG25MnCrNi)铸钢件缺陷常温焊补工艺试验研究

Study on welding to mend the defects in the B^+ class(ZG25MnCrNi) cast steel in normal temperature

车辆转向架B+级(ZG25MnCrNi)铸钢容易在生产中产生裂纹、缩松与缩孔、夹砂等铸造缺陷。针对缺陷的状况,采用模拟大铸钢件的裂纹和缩松与缩孔两种方法,在室温进行了焊补工艺试验研究。测定了焊补接头的硬度分布,观察了相应部位的金相组织,得出:采用不预热焊补模拟裂纹缺陷,在接头近表面HAZ区容易出现淬硬的马氏体组织,硬度值高,由于多道多层焊道的相互热影响,硬度降低,组织一般为铁素体和贝氏体组织;而不预热焊补模拟缩松与缩孔等缺陷,硬度值不高。因此,裂纹焊补时应该采用预热和保温缓冷,缩松与缩孔等缺陷焊补时不预热。

Some defects such as crackle,shrinkage and porosity,sand inclusion,and so on,could be find in the B^＋ Class （ZG25MnCrNi） cast steel bogie of vehicle.Two ways to simulate to weld the crackle,shrinkage and porosity in the big cast steel components in normal temperature,are used.The hardness distribution of the weld is measured.The micro-structure of the weld is observed.The results show that when welding with no preheat,hard Martensite could be found in the HAZ of the cap weld.In muhilayer weld,the hardness become lower and the micro-structure become Ferrite and Bainite.To weld the shrinkage and porosity defects,welding with no preheat could be used because the hard Martensite seldom could be find.