4043铝合金电弧增材冷约束组织特征研究

Microstructure Characteristic of 4043 Aluminum Alloy Produced by Arc Additive Manufacturing Process With Forced Water Cooling Constraint

采用强冷约束辅助电弧增材方法制造4043铝合金薄壁墙体,并对薄壁试样的宏观成型及组织特征进行研究。结果表明,使用强冷约束装置后试样垂直度提高,表面成形精度得到明显改善;平均晶粒尺寸由不加强冷约束时的25μm减小为12μm,晶粒得到明显细化;施加约束后4043铝合金侧壁直接与约束装置接触,使得侧壁散热速度加快,侧壁产生胞状组织,中心为柱状组织且与增材方向呈一定角度生长。薄壁墙体底部到顶部硬度呈现递减规律,硬度平均值由不加约束时的48HV提高到58HV;横向晶粒分布为两侧呈胞状组织,中心区域为柱状组织,中心区域硬度比两侧低。

The 4043 aluminum alloy thin-wall was manufactured by arc additive manufacturing(AM)process with forced water cooling constraint,and the macro-appearance and microstructure of AM specimens were studied.The results revealed that the verticality of the sample and the surface forming precision were improved.The average grain size decreased from 25μm to 12μm when the water cooling constraint was used,and the grain size was obviously refined.When the water cooling constraint device was applied,the 4043 aluminum alloy lateral wall was directly in contact with the restraint device,and the heat quickly dissipated.Therefore,the columnar grain grew in a certain angle.The hardness decreased from the bottom to the top of the AM specimen,and the average value of hardness increased from 48HV without restriction to 58HV.The horizontal grain distribution was cellular grain on both sides,central region was columnar grain,and the hardness of central region was lower than that of both sides.