Abstract: In order to obtain the phosphating process and parameters suitable for the BIW with different ratio of steel and aluminum, the phosphating process and parameters for BIW have been examined experimentally. The experimental are analyzed to find the key points of the phosphating process applicable to steel-aluminum composite BIW.Specifically,when the surface area of aluminum alloy is less than or equal to 20% of the total surface area of the BIW, the aluminium alloy and steel parts can be phosphated in the same bath, whereas the surface area is more than 20%, a two-step pretreatment process should be used.

Key words: steel-aluminum composite BIW, pretreatment, phosphatization, passivation, two-step pretreatment process

摘要： 为找到适合处理钢铝不同混合比例下的磷化工艺及参数，对钢铝混合金属车身的磷化工艺及参数进行了实验研究，通过分析验证数据找到了不同铝合金材料用量条件下磷化工艺过程的关键点，当应用铝合金材料表面积不超过车身总表面 ２０％时，可以使用钢铝同槽磷化工艺，但当超过车身总表面积 ２０％时，需要使用磷化钝化二步法工艺。

关键词: 钢铝混合车身, 前处理, 磷化, 钝化, 二序工艺