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由于母材含有大量气源,气孔是压铸镁合金激光焊最主要的问题。在不同的激光功率密度下,采用不同的热输入对压铸镁合金激光焊气孔形成规律进行了研究。在低激光功率密度(1.6×106W/cm2以下)焊接时,随着热输入的升高气孔率持续升高;在高激光功率密度(3.2×106W/cm2以上)焊接时,在一定热输入下气孔率出现极小值,由此增加或减少热输入都会造成气孔率的升高,但当热输入非常低时气孔率又出现降低的趋势,即不同激光功率密度下气孔率随焊接热输入的变化存在两种不同的规律。结合压铸镁合金母材中气源行为以及焊接热过程,对两种规律的形成原因进行了讨论和实验验证,研究发现获得低气孔率焊缝的关键是抑制压铸镁合金中原子氢的析出,使其以固溶形式继续存在于焊缝中。
As the base metal contains a large number of gas source, stomatal magnesium die-casting laser welding is the most important issue. At different laser power densities, different heat input were used to study the formation of stomatal formation in die-casting magnesium alloy laser welding. At low laser power density (1.6 × 10 6 W / cm 2 or less), the porosity increases continuously with the increase of heat input. At high laser power density (above 3.2 × 10 6 W / cm 2), under certain heat input When the heat input is very low, the porosity decreases again. That is to say, the porosity changes with the welding heat input at different laser power densities There are two different laws of change. According to the behavior of gas source and the welding thermal process in the base metal of die-casting magnesium alloy, the formation causes of the two regularities are discussed and verified. The key to obtain the weld with low porosity is to suppress the precipitation of atomic hydrogen in the die-cast magnesium alloy, So that it continues to exist in the form of solid solution in the weld.