等径角挤压法制备高强铝合金的组织控制研究
发布时间：2018-10-17 19:19
【摘要】：7003铝合金属于A1-Zn-Mg系高强铝合金,具有良好的热变形能力和加工性能,具有优良的可焊性,焊接后可以自动时效,有良好的疲劳强度。近年来,7003铝合金的应用越来越广泛,其被广泛应用于航空航天、汽车工业领域。提高7003铝合金的性能可以使其更好地应用于各领域。 SPD(大塑形变形)技术是晶粒细化以提高材料强度的一种有效方法。研究表明在SPD过程中,当晶粒细化到1μm后,材料将表现出一系列不寻常的物理、化学和力学性能。因此,研究铝合金的晶粒细化方法具有重要的理论意义和应用意义。SPD制备超细晶材料的工艺方法众多,作为细化晶粒的方法之一,等径角挤压技术(ECAP)能够强烈的细化晶粒,且工艺简单、生产成本低、制得的超细晶材料以其优良的性能受到材料科学界的广泛关注,具有良好的应用价值和前景。 论文对7003铝合金进行五道次ECAP(等径角挤压),对挤压后的材料通过金相显微镜、透射电子显微镜及X射线衍射技术进行显微组织观察,结果表明：随着等通道挤压法道次的增加,7003铝合金试样晶粒发生了明显细化,在ECAP过程中,晶界逐渐沿剪切变形方向发生平直化转变。随着挤压道次的增加,材料内部位错密度升高,位错缠结加剧,五道次等通道挤压后,位错密度不再增加反而减少,位错缠结逐渐转变成细小的亚晶粒,平均晶粒尺寸为400nm左右,实现晶粒细化。 对挤压后试样进行了拉伸、压缩实验并进行硬度测试,结果表明：随着等通道挤压道次增加,材料力学性能明显改善。研究显示：从一道次到四道次,抗拉强度由336.17MPa增加到405.33MPa,增加了20.5%；压缩屈服强度由265MPa增加到421MPa,增加了58.9%；试样X面的显微硬度由72.8HV增加到138.4HV,增加了90%。 对挤压后试样进行再结晶退火处理,对比分析不同再结晶退火制度对组织演变的影响,获得试样最佳组织控制工艺为：ECAP四道次,退火温度160℃,保温时间为1h,此时获得的试样晶粒的平均尺寸不会增大,而且有进一步细化的趋势。该研究结果可为进一步深入研究或采用ECAP法生产高强铝合金提供参考。
[Abstract]:7003 aluminum alloy belongs to A1-Zn-Mg high strength aluminum alloy, it has good thermal deformation ability and processing property, excellent weldability, automatic aging after welding, and good fatigue strength. In recent years, 7003 aluminum alloy has been widely used in aerospace and automobile industry. Improving the properties of 7003 aluminum alloy can make it better used in various fields of. SPD (plastic deformation) technology is an effective method of grain refinement to improve the strength of the material. The results show that during the SPD process, when the grain is refined to 1 渭 m, the material will exhibit a series of unusual physical, chemical and mechanical properties. Therefore, it is of great theoretical and practical significance to study the grain refinement method of aluminum alloy. As one of the methods of grain refinement, (ECAP) can refine the grain strongly, as one of the methods of preparing ultrafine grain material by SPD. The ultrafine grained materials with simple process, low production cost and excellent properties have attracted wide attention of the material science community, and have good application value and prospect. In this paper, 7003 aluminum alloy was extruded by ECAP (Equal Channel angular Extrusion) for five times. The microstructure of the extruded aluminum alloy was observed by metallographic microscope, transmission electron microscope and X-ray diffraction technique. The results show that the grain size of 7003 aluminum alloy samples is obviously refined with the increase of the pass number of equal channel extrusion, and the grain boundary changes gradually along the direction of shear deformation during ECAP. With the increase of extrusion pass, the dislocation density inside the material increases, the dislocation entanglement intensifies, the dislocation density decreases instead of increasing, and the dislocation entanglement gradually changes into fine sub-grains. The average grain size is about 400nm to realize grain refinement. The tensile, compression and hardness tests of the extruded samples were carried out. The results showed that the mechanical properties of the samples improved obviously with the increase of the number of extrusion passes. The results show that from one to four passes, the tensile strength increases from 336.17MPa to 405.33 MPa, the compressive yield strength increases from 265MPa to 421 MPa and increases 58.9%, and the microhardness of the X plane increases from 72.8HV to 138.4 HVV, which increases 90%. The effect of different recrystallization annealing systems on the microstructure evolution of the extruded samples was compared and analyzed. The results showed that the optimum microstructure control process was as follows: ECAP four times, annealing temperature 160 鈩，
本文编号：2277697
[Abstract]:7003 aluminum alloy belongs to A1-Zn-Mg high strength aluminum alloy, it has good thermal deformation ability and processing property, excellent weldability, automatic aging after welding, and good fatigue strength. In recent years, 7003 aluminum alloy has been widely used in aerospace and automobile industry. Improving the properties of 7003 aluminum alloy can make it better used in various fields of. SPD (plastic deformation) technology is an effective method of grain refinement to improve the strength of the material. The results show that during the SPD process, when the grain is refined to 1 渭 m, the material will exhibit a series of unusual physical, chemical and mechanical properties. Therefore, it is of great theoretical and practical significance to study the grain refinement method of aluminum alloy. As one of the methods of grain refinement, (ECAP) can refine the grain strongly, as one of the methods of preparing ultrafine grain material by SPD. The ultrafine grained materials with simple process, low production cost and excellent properties have attracted wide attention of the material science community, and have good application value and prospect. In this paper, 7003 aluminum alloy was extruded by ECAP (Equal Channel angular Extrusion) for five times. The microstructure of the extruded aluminum alloy was observed by metallographic microscope, transmission electron microscope and X-ray diffraction technique. The results show that the grain size of 7003 aluminum alloy samples is obviously refined with the increase of the pass number of equal channel extrusion, and the grain boundary changes gradually along the direction of shear deformation during ECAP. With the increase of extrusion pass, the dislocation density inside the material increases, the dislocation entanglement intensifies, the dislocation density decreases instead of increasing, and the dislocation entanglement gradually changes into fine sub-grains. The average grain size is about 400nm to realize grain refinement. The tensile, compression and hardness tests of the extruded samples were carried out. The results showed that the mechanical properties of the samples improved obviously with the increase of the number of extrusion passes. The results show that from one to four passes, the tensile strength increases from 336.17MPa to 405.33 MPa, the compressive yield strength increases from 265MPa to 421 MPa and increases 58.9%, and the microhardness of the X plane increases from 72.8HV to 138.4 HVV, which increases 90%. The effect of different recrystallization annealing systems on the microstructure evolution of the extruded samples was compared and analyzed. The results showed that the optimum microstructure control process was as follows: ECAP four times, annealing temperature 160 鈩，
本文编号：2277697
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