【摘要】 采用单辊熔体旋转冷却法,在400～500℃温度下进行热挤压,制得超细晶7075铝合金棒材;然后对其组织、力学性能以及拉伸断口等进行测试和分析。结果表明,采用快速凝固方法能显著地细化晶粒,制备的带材平均晶粒尺寸小于1μm。超细晶带材经热挤压得到的棒材与传统铸造热挤压棒材相比,晶粒得到了显著细化,力学性能更优。随着热挤压温度升高,棒材组织逐渐致密,虽然晶粒有所粗化,但强度和塑性仍有所提升;在挤压温度为500℃时,热挤压棒材获得最优的力学性能,其抗拉强度为517.1 MPa,断后伸长率为23.2%;与传统铸造热挤压相比,抗拉强度提高了12.0%,伸长率提高了51.6%。更多还原

【Abstract】 7075(Al-Zn-Mg-Cu)ultrafine-grained aluminum alloy ribbon was prepared by single roller melt rotary cooling method,and hot extrusion was performed at 400～500 ℃to obtain ultrafine grain 7075 aluminum alloy bar.The microstructure,mechanical properties and tensile fracture of the extruded bar were tested and analyzed.Scanning electron microscopy(SEM)analysis indicates that the rapid solidification method can refine significantly the grains,and the average grain size of the prepared ribbon is less than 1μm.The back-scatter diffraction(EBSD)results demonstrate that the bar obtained by hot extrusion from the ultrafine grain ribbon presents a significantly finer grain and better mechanical performance than the conventional cast hot extruded bar.Under the test conditions,with the hot extrusion temperature increase,microstructure of the extruded bar is gradually densified.Although the grains are coarsened,the strength and plasticity are still improved.At 500℃,the hot extruded bar exhibits the desirable mechanical performance,where the tensile strength and elongation reach 517.1 MPa and 23.2%,increased by 12.0%and 51.6%,respectively,compared with those of the traditional casting hot extrusion bar.更多还原