通过宏观和微观检验、化学成分分析、硬度测试以及能谱分析等方法,对ADC10压铸铝合金汽车变速箱体中出现硬质点的原因进行了分析。结果表明:硬质点的产生是由于熔融铝液中的氧化物或含钛型金属化合物在压铸过程中随同铝液一起注射进入模具型腔并最终保留在零件内部。其后机械加工时,硬质点的存在致使刀具损坏,机械加工难以正常进行,严重时导致变速箱体报废。最后提出改进铝液的前处理工艺,避免氧化物或金属化合物进入模具型腔,可有效防止硬质点的产生。

The reason of hard spots were analyzed in die casting transmission case of ADC10 aluminum alloy by means of macroscopic and microscopic examination, chemical composition analysis, hardness testing, energy spectrum analysis and so on. The results showed that the hard spots were due to the oxidizing material or metallic compounds containing titanium, together with liquid aluminum injected in mould cavity and finally reserved inside of the section in the process of die-casting. After that, in the machining operation, the existence of hard spots caused damage of cutter, which caused cutting hardly to work normally, It even may cause seriously damage to scrap transmission case. To improve the pre treatment process of liquid aluminum, avoiding oxidizing material or metallic compound entered mould cavity, this would be effective to prevent the generation of hard spots.