搅拌摩擦加工制备细晶5083铝合金及其超塑性性能研究
发布时间：2018-09-18 12:07
【摘要】：搅拌摩擦加工可以细化材料的晶粒,提高材料的力学性能,塑性也会有明显的增加。本文首先开展单道次搅拌摩擦加工实验,采用正交试验法选取最具代表性的搅拌头旋转速度、进给速度、轴肩下压量工艺参数组,对5mm厚的5083铝合金进行搅拌摩擦加工。对加工试样进行拉伸试验、金相试验、硬度试验和断口分析,研究各参数下搅拌区域的组织和性能情况,得到最优的搅拌摩擦加工工艺参数。然后使用得到的工艺参数对5083铝合金进行多道次搅拌摩擦加工。多道次搅拌摩擦加工将研究最优的搅拌头平移距离,从而制备大面积晶粒细化的5083铝合金材料;研究温度、搅拌头形状对材料晶粒尺寸的影响并尝试了用板材堆叠的方法来制备大厚度的细晶材料。对多道次搅拌摩擦加工得到的大面积细晶5083铝合金进行高温拉伸试验,研究其细晶超塑性性能。使用ABAQUS有限元软件分别模拟超塑性板材和普通板材的挤压、冲压成形。本论文的具体研究结果如下:(1)获得了单道次加工的最优工艺参数。当搅拌头转速为1300r/min、进给速度为400mm/min、下压量为0.3mm时,经过加工的试样表面无宏观缺陷。试样的抗拉强度为214MPa,达到母材的93.05%;屈服强度为112.4MPa;断后延伸率为18.37%。5083铝合金材料在经过搅拌摩擦加工后,搅拌区域的晶粒被打碎,由原本沿轧制方向被拉长的粗大晶粒变成细小的等轴晶粒。搅拌摩擦加工后搅拌区域的硬度小于母材区,出现一段尺寸与搅拌针尺寸基本吻合的软化区。(2)多道次搅拌摩擦加工方面。最优道次间隔与搅拌针端部直径相同。因搅拌头轴肩与板材的接触面积要比搅拌针表面积大,摩擦产生的热量也较多,从而导致上部区域的晶粒在高温下长大,尺寸大于下部区域。在搅拌摩擦加工过程中进行加水冷却可以降低上部区域的温度,从而减小上部区域的晶粒尺寸。相比于圆锥形搅拌头,在使用圆柱形搅拌头进行加工时,晶粒更加粗大,不利于细晶材料的制备。使用堆叠多道次搅拌摩擦加工的方法,可以制备大厚度晶粒细化的5083铝合金材料。(3)超塑性成形方面。高温拉伸试验表明:在应变速率为3×10-3/s,温度为530°C时,经过加工试样的延伸率最大,达到216%;而未经过加工的试样在相同应变速率和温度下延伸率仅为83%。细晶超塑性5083铝合金在成形时塑性和金属流动性更好,有限元仿真分析表明,超塑性成形时所需对凸模施加的压力更小。
[Abstract]:Friction stir processing can refine the grain size of the material, improve the mechanical properties of the material, and increase the plasticity obviously. In this paper, the single pass friction stir experiment was carried out, and the most representative process parameters of rotating speed, feed speed and axial shoulder pressure were selected by orthogonal test. The 5083 aluminum alloy with 5mm thickness was processed by friction stir. The tensile test, metallographic test, hardness test and fracture analysis were carried out to study the microstructure and properties of the stir region under various parameters, and the optimum technological parameters of friction stir processing were obtained. Then the 5083 aluminum alloy was processed by multi-pass friction stir with the obtained process parameters. Multi-pass friction stir processing will study the optimal translational distance of the stir head, so that the 5083 aluminum alloy material with large area grain refinement will be prepared, and the temperature will be studied. The effect of mixing head shape on the grain size of the material was studied and the method of plate stacking was used to prepare the fine grain material with large thickness. The high temperature tensile test of large area fine grain 5083 aluminum alloy obtained by multi-pass friction stir processing was carried out and the superplasticity of fine grain was studied. The ABAQUS finite element software is used to simulate the extrusion and stamping of superplastic sheet and common sheet respectively. The results of this paper are as follows: (1) the optimal process parameters of single pass machining are obtained. When the speed of the mixing head is 1 300 r / min, the feed speed is 400 mm / min and the pressure is 0.3mm, the surface of the processed sample has no macroscopic defects. The tensile strength of the sample is 214MPa, which reaches 93.05 of the base metal, the yield strength is 112.4MPa, and the elongation after breaking is 18.37.5083 aluminum alloy material, after friction stirring, the grains in the stirring region are broken. The coarse grains which were originally elongated along the rolling direction were changed into fine equiaxed grains. The hardness of the stir region is smaller than that of the base metal area after friction stir processing, and there is a softening zone in which the size of the stir needle basically coincides with the size of the stir needle. (2) the multi-pass friction stir processing. The optimal interval is the same as the diameter of the end of the stirring needle. Because the contact area between the shaft shoulder and the plate is larger than that of the agitator needle and the heat produced by friction is more than that of the stirring needle the grain in the upper region grows at high temperature and the size is larger than that in the lower part. Water cooling during friction stir processing can reduce the temperature of the upper region and decrease the grain size of the upper region. Compared with the conical mixing head, the grain size is thicker when the cylindrical stirring head is used, which is not conducive to the preparation of fine crystal material. 5083 aluminum alloy materials with large thickness grain refinement can be prepared by stacking multi-pass friction stir processing. (3) superplastic forming. The results of high temperature tensile test show that the maximum elongation of the processed sample is 2166C at the strain rate of 3 脳 10 ~ (-3) / s and the temperature of 530 掳C, while the elongation of the unmachined sample is only 833 at the same strain rate and temperature. The finite-grain superplastic 5083 aluminum alloy has better plasticity and metal fluidity during forming. The finite element simulation analysis shows that the pressure applied to the punch is lower during superplastic forming.
【学位授予单位】：浙江理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG146.21;TG453.9
本文编号：2247855
[Abstract]:Friction stir processing can refine the grain size of the material, improve the mechanical properties of the material, and increase the plasticity obviously. In this paper, the single pass friction stir experiment was carried out, and the most representative process parameters of rotating speed, feed speed and axial shoulder pressure were selected by orthogonal test. The 5083 aluminum alloy with 5mm thickness was processed by friction stir. The tensile test, metallographic test, hardness test and fracture analysis were carried out to study the microstructure and properties of the stir region under various parameters, and the optimum technological parameters of friction stir processing were obtained. Then the 5083 aluminum alloy was processed by multi-pass friction stir with the obtained process parameters. Multi-pass friction stir processing will study the optimal translational distance of the stir head, so that the 5083 aluminum alloy material with large area grain refinement will be prepared, and the temperature will be studied. The effect of mixing head shape on the grain size of the material was studied and the method of plate stacking was used to prepare the fine grain material with large thickness. The high temperature tensile test of large area fine grain 5083 aluminum alloy obtained by multi-pass friction stir processing was carried out and the superplasticity of fine grain was studied. The ABAQUS finite element software is used to simulate the extrusion and stamping of superplastic sheet and common sheet respectively. The results of this paper are as follows: (1) the optimal process parameters of single pass machining are obtained. When the speed of the mixing head is 1 300 r / min, the feed speed is 400 mm / min and the pressure is 0.3mm, the surface of the processed sample has no macroscopic defects. The tensile strength of the sample is 214MPa, which reaches 93.05 of the base metal, the yield strength is 112.4MPa, and the elongation after breaking is 18.37.5083 aluminum alloy material, after friction stirring, the grains in the stirring region are broken. The coarse grains which were originally elongated along the rolling direction were changed into fine equiaxed grains. The hardness of the stir region is smaller than that of the base metal area after friction stir processing, and there is a softening zone in which the size of the stir needle basically coincides with the size of the stir needle. (2) the multi-pass friction stir processing. The optimal interval is the same as the diameter of the end of the stirring needle. Because the contact area between the shaft shoulder and the plate is larger than that of the agitator needle and the heat produced by friction is more than that of the stirring needle the grain in the upper region grows at high temperature and the size is larger than that in the lower part. Water cooling during friction stir processing can reduce the temperature of the upper region and decrease the grain size of the upper region. Compared with the conical mixing head, the grain size is thicker when the cylindrical stirring head is used, which is not conducive to the preparation of fine crystal material. 5083 aluminum alloy materials with large thickness grain refinement can be prepared by stacking multi-pass friction stir processing. (3) superplastic forming. The results of high temperature tensile test show that the maximum elongation of the processed sample is 2166C at the strain rate of 3 脳 10 ~ (-3) / s and the temperature of 530 掳C, while the elongation of the unmachined sample is only 833 at the same strain rate and temperature. The finite-grain superplastic 5083 aluminum alloy has better plasticity and metal fluidity during forming. The finite element simulation analysis shows that the pressure applied to the punch is lower during superplastic forming.
【学位授予单位】：浙江理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG146.21;TG453.9
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