热挤压对喷射沉积7055铝合金显微组织和力学性能的影响

Effect of hot extrusion on microstructures and mechanical properties of spray-formed 7055 aluminum alloy

采用全自动控制往复喷射成形工艺制备工业规格7055铝合金锭坯，研究热挤压工艺对喷射成形7055铝合金的显微组织和力学性能的影响。采用电子背散射衍射技术对经不同热挤压后7055铝合金的织构进行研究。结果表明，喷射沉积锭坯组织为等轴状晶粒，均匀细小（30～50gm），基体中不存在枝晶型偏析。由于喷射沉积工艺本身的特点，在合金中存在大量的显微疏松缺陷。沉积锭坯经过热挤压致密化后，合金力学性能显著提高，抗拉强度巩为390MPa，伸长率6为13．3％，表明热挤压工艺可有效消除疏松缺陷，从而充分发挥出喷射沉积工艺的优越性。EBSD分析表明，挤压后沿着挤压轴方向形成丝织构，主要为（001）与（111）两种织构。

A large-scale 7055 A1 alloy billet was prepared by fully automatic controlled reciprocating spray forming technology. The initial microstructure and the effect of subsequent hot extrusion on the microstructures and mechanical properties of the 7055 alloy were studied. Texture of 7055 aluminum alloy after hot extrusion at different extrusion ratio was studied by electron back-scatter diffraction （EBSD） technology. The results show that the as-deposited billet has an equiaxed grain and homogeneous structure with a grain size of 30-50 pm and there is no dendrite segregation structure. Due to the characteristics of spray deposition process, there are a large number of micro-porosity defects in the alloy matrix. The ultimate tensile strength of as-deposited materials after hot extrusion rises to 390 MPa, and the elongation is 13.3%, which indicates that hot extrusion process can effectively eliminate the porosity defect. The result of electron back-scatter diffraction （EBSD） show that there exist （111） and （001） textures along the direction of extrusion axis in the hot extruded aluminum alloy bars.