ZK60镁合金板材轧制工艺研究
发布时间：2019-01-05 16:20
【摘要】：镁合金作为21世纪最轻的金属材料受到日益广泛的重视,其低密度、高比强度及易于回收等优点使镁合金在越来越多的领域得到广泛应用。而ZK60镁合更是一种典型的高强镁合金,但其在铸造过程中容易产生晶间化合物MgZn相,导致热轧过程中热裂倾向及加工硬化严重,轧制性能差。本文以自制ZK60镁合金为研究对象,通过均匀化-热轧-冷轧-退火的变形工艺,从变形机理和织构变化角度研究轧制温度、道次变形量、轧制方式及退火处理对金相组织、织构及力学性能的影响,具体结论如下:(1)轧制温度升高,会促使合金中非基面滑移系启动,导致动态再结晶程度增加,晶粒细化。400℃轧制时平均晶粒尺寸最小为9.35μm,同时(0002)基面织构最弱。(2)增加道次压下量会提高组织中位错密度,促进动态再结晶程度增加,从而降低平均晶粒尺寸,同时(0002)基面织构强度增加。但变形量太大会降低组织均匀性,从而影响力学性能。(3)交叉轧制会促进二次孪晶生成,同时非基面滑移系的启动促使晶间变形加剧,导致动态再结晶程度增加,细化晶粒。晶粒细化有利于晶粒旋转和晶界移动,改变轧制方向会迫使原先向轧制方向旋转的晶粒向TD方向偏移,最终导致(0002)基面织构强度由8.61降到7.12,,织构类型由(0001)[0(?)10](0°,120°)转变为(0001)[(?)(?)30](0°,139.11°)和((?)105)[2(?)11](20.16°,18.02°,60°)。晶粒细化和织构弱化导致合金塑性提高,各向异性降低。(4)退火温度升高,会加快静态再结晶完成时间,提高合金的力学性能,但退火温度过高会导致晶粒粗化,降低强度和塑性。延长退火时间,合金的强度和塑性会先增加后下降。同时合理的退火工艺会降低织构强度。本文最终的退火工艺选择为340℃×1h。(5)通过显微硬度测试法表征合金退火时的静态再结晶过程,得出静态再结晶完成时间,从而计算出20%冷轧量的ZK60镁合金激活能Q为58.8KJ/mol,并得出该合金在不同退火温度下的静态再结晶分数与保温时间关系的方程。
[Abstract]:Magnesium alloys, as the lightest metal materials in the 21st century, have been paid more and more attention. Their advantages of low density, high specific strength and easy to be recovered have made magnesium alloys widely used in more and more fields. ZK60 magnesium bonding is a typical high strength magnesium alloy, but it is easy to produce intergranular compound MgZn phase in the casting process, which leads to the hot cracking tendency and work hardening in hot rolling process, and the rolling performance is poor. In this paper, the microstructure of ZK60 magnesium alloy was studied by homogenization, hot rolling, cold rolling and annealing, from the point of view of deformation mechanism and texture change, rolling temperature, pass deformation, rolling mode and annealing treatment. The effects of texture and mechanical properties are as follows: (1) the increase of rolling temperature will lead to the initiation of non-base slip system of the alloy and increase the degree of dynamic recrystallization. The average grain size is 9.35 渭 m and (0002) texture is the weakest. (2) increasing pass reduction will increase dislocation density and increase dynamic recrystallization. Thus the average grain size is reduced and the (0002) basal texture strength is increased. However, the amount of deformation can reduce the homogeneity of microstructure and affect the mechanical properties. (3) Cross rolling will promote the formation of secondary twins, and the starting of non-basal slip system will aggravate the deformation between grains and increase the degree of dynamic recrystallization. Refine the grain. Grain refinement is beneficial to grain rotation and grain boundary movement. Changing rolling direction will force the original rolling direction to shift to TD direction, resulting in the (0002) base texture strength decreasing from 8.61 to 7.12%. The texture types changed from (0001) [0 (?) 10] (0 掳, 120 掳) to (0001) [(?) 30] (0 掳, 139.11 掳) and (?) 105) [2 (?) 11] (20.16 掳, 18.02 掳, 60 掳). Grain refinement and texture weakening increase the plasticity and decrease the anisotropy of the alloy. (4) annealing temperature increases the completion time of static recrystallization and improves the mechanical properties of the alloy, but too high annealing temperature will lead to grain coarsening. Reduce strength and plasticity. When annealing time is prolonged, the strength and plasticity of the alloy will increase first and then decrease. At the same time, reasonable annealing process will reduce the texture strength. In this paper, the final annealing process is 340 鈩，
本文编号：2402008
[Abstract]:Magnesium alloys, as the lightest metal materials in the 21st century, have been paid more and more attention. Their advantages of low density, high specific strength and easy to be recovered have made magnesium alloys widely used in more and more fields. ZK60 magnesium bonding is a typical high strength magnesium alloy, but it is easy to produce intergranular compound MgZn phase in the casting process, which leads to the hot cracking tendency and work hardening in hot rolling process, and the rolling performance is poor. In this paper, the microstructure of ZK60 magnesium alloy was studied by homogenization, hot rolling, cold rolling and annealing, from the point of view of deformation mechanism and texture change, rolling temperature, pass deformation, rolling mode and annealing treatment. The effects of texture and mechanical properties are as follows: (1) the increase of rolling temperature will lead to the initiation of non-base slip system of the alloy and increase the degree of dynamic recrystallization. The average grain size is 9.35 渭 m and (0002) texture is the weakest. (2) increasing pass reduction will increase dislocation density and increase dynamic recrystallization. Thus the average grain size is reduced and the (0002) basal texture strength is increased. However, the amount of deformation can reduce the homogeneity of microstructure and affect the mechanical properties. (3) Cross rolling will promote the formation of secondary twins, and the starting of non-basal slip system will aggravate the deformation between grains and increase the degree of dynamic recrystallization. Refine the grain. Grain refinement is beneficial to grain rotation and grain boundary movement. Changing rolling direction will force the original rolling direction to shift to TD direction, resulting in the (0002) base texture strength decreasing from 8.61 to 7.12%. The texture types changed from (0001) [0 (?) 10] (0 掳, 120 掳) to (0001) [(?) 30] (0 掳, 139.11 掳) and (?) 105) [2 (?) 11] (20.16 掳, 18.02 掳, 60 掳). Grain refinement and texture weakening increase the plasticity and decrease the anisotropy of the alloy. (4) annealing temperature increases the completion time of static recrystallization and improves the mechanical properties of the alloy, but too high annealing temperature will lead to grain coarsening. Reduce strength and plasticity. When annealing time is prolonged, the strength and plasticity of the alloy will increase first and then decrease. At the same time, reasonable annealing process will reduce the texture strength. In this paper, the final annealing process is 340 鈩，
本文编号：2402008
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