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研究了真空电子束焊接热效应对AZ91D和AZ31B镁合金焊缝显微硬度的影响机制,实验结果表明,真空电子束焊接热效应对AZ91D、AZ31B镁合金焊缝均有不同程度的强化作用。当焊接热输入较大时,影响AZ91D镁合金焊缝硬度的主要因素为因Mg元素烧损而产生的强化相变化,焊接热输入越大,焊缝中的Mg元素烧损增加,使Al元素含量(质量分数,下同)逐渐增加,从而在焊缝中生成了更多的强化β相,使焊缝硬度得到提高,产生的强化相越多,焊缝硬度相对越大;当焊接热输入较小时,影响AZ31B镁合金焊缝硬度的主要因素为焊后冷却速度,焊接热输入越小,焊后冷却速度越快,焊缝晶粒越细小,焊缝硬度相对越大。
The effects of vacuum electron beam welding heat effect on the microhardness of AZ91D and AZ31B magnesium alloy weld were studied. The experimental results show that the vacuum electron beam welding thermal effect has different degree of strengthening effect on AZ91D, AZ31B magnesium alloy weld. When the welding heat input is large, the main factor affecting the weld hardness of AZ91D magnesium alloy is the strengthening phase change due to the loss of Mg element. The greater the welding heat input, the more the loss of Mg element in the weld increases, Content (mass fraction, the same below) is gradually increased, resulting in the weld to generate more enhanced β phase, so that the weld hardness is increased, resulting in more strengthening phase, the weld hardness is relatively large; when the welding heat input The main factors that influence the hardness of AZ31B magnesium alloy weld are the cooling rate after welding, the smaller the welding heat input, the faster the cooling rate after welding, the finer the weld bead and the larger the hardness of the weld.