摘要
焊接接头软化是高速列车用6N01铝合金焊接时普遍存在的问题。采用脉冲熔化极气体保护焊(脉冲MIG焊)对8 mm厚6N01-T5铝合金进行焊接,结合温度测量曲线和显微硬度分布确定焊接接头的软化区对应的温度区间及其位置;通过差示扫描量热仪和透射电镜观察析出相的相变规律和形态,分析焊接接头的软化机理。结果表明,焊接接头软化最严重部位距焊缝中心约9 mm,最低硬度值为53 HV,与母材相比下降约34 HV;软化区析出粗大的β相,并且部分含O、Fe等杂质元素的析出相长大至微米级,析出强化效果严重减弱,导致接头发生软化。
The softening of welded joint is a common problem in the welding of 6N01 aluminum alloy tbr high speed trains. The welding of 8 nun thick 6N01-T5 aluminum alloy was carried out by pulse MIG welding.The temperature range and the location for the softening zone of the welded joint were determined by the temperature measurement curve and the microhardness distribution. The phase transformation and morphology of the precipitates were observed by differential scanning calorimeter and transmission electron microscope to analyze the softening behavior of the welded joint. The results show that the area of welded joint with the lowest microhardness value is about 9 mm far away from the weld center and the minimum microhardness of the sottening zone is 53 HV, which is 34 HV lower than that of the base metal. The coarse β phase is precipitated in the soitening zone, some precipitated phase containing O, Fe and other impurities grows to micron level, and the precipitation strengthening effect is weakened seriously, which causes the softening of the welded joint.
出处
《热加工工艺》
CSCD
北大核心
2017年第21期185-188,共4页
Hot Working Technology
基金
国家自然科学基金资助项目(51205106)
河北省自然科学基金项目(E2016208077)
关键词
6N01铝合金
软化现象
析出相
差示扫描量热仪
6N01 aluminum alloy
softening phenomena
precipitated phase
differential scanning calorimeter
