熔体旋转快速凝固和热挤压制备7075铝合金棒材
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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%。
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.
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.
引文
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[2]POLMEAR I J.Light Alloys:From Traditional Alloys to Nano Crystals(4Edition)[M].Amsterdam:Elsevier,2006.
[3]白志玲.铝合金的研究现状及应用[J].科技广场,2015(12):18-20.
[4]蔡其刚.铝合金在汽车车体上的应用现状及发展趋势探讨[J].轻工科技,2009,25(1):28-29.
[5]LUONG D D,III O M S,HAMMOND V H,et al.Development of high performance lightweight aluminum alloy/SiC hollow sphere syntactic foams and compressive characterization at quasi-static and high strain rates[J].Journal of Alloys&Compounds,2013,550(4):412-422.
[6]MOLNROVO,MLEK P REMYSL,LUKˇF,et al.Spark plasma sintering of a gas atomized Al7075alloy:Microstructure and properties[J].Materials,2016,9(1 004):1-15.
[7]ROKNI M R,WIDENER C A,CRAWFORD G A.Microstructural evolution of 7075 Al gas atomized powder and high-pressure cold sprayed deposition[J].Surface and Coatings Technology,2014,251:254-263.
[8]MEYDANOGLU O,JODOIN B,KAYALI E S.Microstructure,mechanical properties and corrosion performance of 7075Al matrix ceramic particle reinforced composite coatings produced by the cold gas dynamic spraying process[J].Surface and Coatings Technology,2013,235:108-116.
[9]赵立华.超高强度铝合金研究现状及发展趋势[J].兵器装备工程学报,2011,32(10):147-150.
[10]肖渊,齐乐华,曾祥辉,等.气压驱动金属微熔滴可控喷射及沉积精度分析[J].机械工程学报,2011,47(15):156-160.
[11]邓延波,赵荣涛,冯骥,等.快速凝固技术在铝合金中的应用[J].科技信息,2012(25):476-477.
[12]YAN S Q.Influence of rapid solidification on the microstructural development of zinc-aluminum alloys[J].Metallography Microstructure&Analysis,2014,3(2):147-151.
[13]LAVERNIA E J,AYERS J D,SRIVATSAN T S.Rapid solidification processing with specific application to aluminium alloys[J].Metallurgical Reviews,2013,37(1):1-44.
[14]SHARMA S S,JAGANNATH K,PRABHU P R.Microstructure and mechanical characterization of heat treated stir cast silica(sea sand)reinforced 7xxx Al alloy MMCs[J].International Journal of Remote Sensing,2013,29(23):7 003-7 028.
[15]QU Y,SU R,YOU J,et al.Study on microstructure,mechanical properties and corrosion behavior of spray formed 7075alloy[J].Materials Today Communications,2015(4):109-115.
[16]YAN S Q.Influence of rapid solidification on the microstructural development of zinc-aluminum alloys[J].Metallography Microstructure&Analysis,2014,3(2):147-151.
[17]YAMAGUCHI M,BERNHARDT J,FAERSTEIN K,et al.Fabrication and characteristics of melt-spun Al ribbons reinforced with nano/micro-BN phases[J].Acta Materialia,2013,61(20):7 604-7 615.
[18]JEYAKUMAR M,KUMAR S,GUPTA G S.Microstructure and properties of the spray-formed and extruded 7075Al alloy[J].Materials and Manufacturing Processes,2010,25(8):777-785.
[19]吴博.快速凝固/粉末冶金制备块体5083纳米晶铝合金研究[D].河北秦皇岛:燕山大学,2013.
[20]FLORES C,ESTRA D,MIKIYO S,et al.Microstructure and mechanical properties of 7075 aluminum alloy nanostructured composites processed by mechanical milling and indirect hot extrusion[J].Materials Characterization,2012,63(1):39-46.