铝合金感应加热半固态重熔及复杂件触变成形

Semi-solid Microstructure Evolution of Aluminum Alloy Under Induction Heating and thixoforming of Complex Parts

目的研究铝合金半固态坯料在感应加热过程中的组织演变规律,并实现复杂构件近净成形。方法对7075-T6铝合金挤压棒料进行感应加热条件下的半固态等温处理,观察其微观组织演变规律,并对其进行金相分析,研究晶粒粗化机制;随后采用梯度感应加热坯料进行触变-塑变复合成形试验。结果晶粒随保温温度的升高,或保温时间的增加,尺寸逐渐增加;随保温时间的延长,晶粒圆整度逐渐增加。晶粒的长大主要以Ostwald熟化机制为主,合并长大为辅,且由于感应加热速率(5℃/s)较快,最终形成的晶粒较小。计算得出,晶粒在590,600,610,620℃时的晶粒粗化速率分别为165,226,309,497μm^3/s。采用梯度感应加热坯料,实现了某型铝合金尾翼构件的近净成形。结论适用于7075铝合金触变成形的感应加热工艺参数为:在610~620℃下保温5~10 min。集成感应加热半固态重熔处理和触变-塑变复合成形技术,可实现复杂构件近净成形。

This paper aims to study rules for microstructure evolution of semi-solid aluminum alloy blank in induction heating and achieve near-net forming of complex structure.Extruded7075-T6aluminum alloy was treated isothermally at semi-solid state in induction remelted condition to observe the rule of its microstructure evolution,analyze its metallographic phase and research the grain growth coarsening mechanism.Subsequently,the compound forming based on functional integration of plastic deformation and thixoformation was conducted based on the induction remelted slug.The grain size increased with the increase of holding temperature and holding time.The shape factor of solid grains also increased with the increase of holding time.Ostwald ripening was the dominant grain coursing mechanism.The grain sizes were relatively small because of high heating rate(5℃/s)of induction heating.In addition,the grain growth rates were165,226,309and497μm3/s at590,600,610and620℃,respectively.Near-net forming of aluminum alloy was achieved by induction remelted slug.The most appropriate induction heating parameters for thixoforming of7075aluminium alloy are:610~620℃for5~10min.Based on the integration of induction remelting and compounding forming technologies,complex components can be neat net shaped successfully.