不同焊接方法下超细晶粒钢焊接接头研究

Research on Welded Joint of Ultra-fine Grain Steel under Different Welding Methods

用手工电弧焊和CO_2气体保护焊焊接超细晶粒钢WCX355,研究并对比了两种焊接方法下超细晶粒钢焊接接头。结果表明:由于采用的是2.5mm焊条、低的焊接电流和快的焊接速度,超细晶粒钢手工电弧焊焊缝区在电流较小时多呈等轴晶,随着电流的增大树枝状晶增多。而超细晶粒钢CO_2气体保护焊由于采用的电流较大,焊缝区均为树枝状晶。过热区的组织随焊接电流增大而增大,CO_2气体保护焊的过热区比手工电弧焊的过热区组织形貌分布更均匀。两种焊接方法下正火区均为比母材细小的铁素体和珠光体。两种焊接方法下,超细晶粒钢的焊接接头硬度均高于母材,未出现软化现象。

Ultra-fine grain steel WCX355 was welded by manual arc welding and CO2 gas shielded arc welding and welded joints of ultra-fine grain steel under two welding methods were researched in this paper. The result showed that weld zone microstructure of ultra-fine grain steel manual arc welding was equiaxed grain when current was low and dendritic crystal increased with current increasing because of using 2.5 mm electrode, low welding current and fast welding speed. Weld zone microstructure of ultra-fine grain steel CO2 gas shielded arc welding was dendritic crystal because larger current was used. Overheated zone microstructure increased with the increase of current. Microstructure morphology distribution of overheated zone of CO2 gas shielded arc welding was more uniform than manual arc welding. Normalized zone was ferrite and pearlite which was finer than base metal under two welding methods. Hardness of welded joint was higher than base metal and softening phenomena did not appear under two welding methods.