锻造活塞裙用4032d高硅铝合金棒材生产工艺研究

Study on production process of forging piston skirt with 4032d high-silicon aluminum alloy rod

针对4032d高硅铝合金生产中常出现初晶硅聚集、共晶硅尺寸大、气孔夹杂严重、机械加工性能差、力学性能低等问题,在熔铸过程分别采用多种变质剂处理熔体试验,采用不同的精炼、净化处理试验方案;试验研究铸锭均匀化处理制度、挤压工艺和挤压棒材热处理工艺制度。得出锻造活塞裙用4032d高硅铝合金棒材合理的生产工艺：加质量分数为0.6%的复合钠盐变质处理熔体,变质处理前用N2、Cl2混合气体精炼,变质处理后用N2气精炼,采用隔热膜铸造法,生产出几乎无初晶硅、共晶硅细小、气孔夹杂少的铸锭;铸锭均匀化温度500℃~515℃,棒材挤压温度420℃,固溶处理温度510℃,时效制度165℃3h。

To eliminate the problems happened during forging 4032d high-silicon aluminum alloy,such as：primary crystal silicon aggregation,large eutectic silicon size,poor machining property and low mechanical properties,the following measures have been adopted during melting and casting,for instance：various transformative agents,different refining and cleaning methods,homogenizing processes and extruding technologies have been investigated for the rod stock.Heat treatment systems of the extruded rod,which is the stock of piston skirt,have been tested.The reasonable production processes of 4032d high-silicon aluminum alloy rod have been got.It means that 0.6% of compound sodium salt as transformative agent put in the melt.N2＋Cl2 mixed gas has been used for refining before transformation and N2 has been used after it for refining.Heat-isolation cast mold was used.And the ingot produced with these technologies is almost without primary crystal silicon but with tiny eutectic silicon and little gas-inclusions.The homogenization temperature is 500℃-515℃.The extrusion temperature is 420℃,solution heat treatment is 510℃,and the aging temperature is 165℃ with 3 hours holding.