连续变断面循环挤压TC11合金的工艺优化及其组织细化机理研究
发布时间：2018-08-25 11:41
【摘要】：晶粒细化是改善和提高金属材料性能的有效途径之一,目前采用大塑性变形方法制备细晶材料依然存在一些问题,如加工的工件尺寸较小,存在明显的织构倾向等。连续变断面循环挤压(Continuous Variable Cross-section Recycled Extrusion,CVCE)是制备大规格块体细晶材料的一种新型大塑性变形方法,其操作相对简单,生产效率高,并且在变形过程中能够实现变形体的均匀控制,有利于工业化生产的实现。本文对TC11合金进行连续变断面循环挤压变形,并对变形后的材料进行热处理,研究了变形工艺参数以及热处理制度对合金组织性能的影响,并采用DEFORM软件对变形效果较好的一组工艺参数(850℃,6道次,5mm/s)试样的温度场、应力场及应变场进行模拟。主要研究内容及结论如下:(1)采用不同的工艺参数对TC11合金进行连续变断面循环挤压,分析了变形温度、变形道次、变形速度对其组织的影响。结果表明:当变形温度在再结晶温度范围内时,随着循环道次的增加,晶粒的细化程度以及均匀程度增加;而在较高温度(950℃)变形时,TC11晶粒的细化程度先增大再减小。综合分析,可获得较优的工艺参数为850℃,6道次,5mm/s,初生α相尺寸由10μm细化至4~4.5μm左右,细化效果较显著,且组织分布均匀。1(2)研究了退火温度及退火时间对连续变断面循环挤压变形后TC11合金组织结构的影响。选择接近再结晶的温度进行双重退火处理,变形工艺参数为850℃,6道次,2mm/s和850℃,6道次,5mm/s的最优热处理制度为:(850℃,1h,AC)+(530℃,1h,AC),初生α相尺寸为3~4μm,且晶界清晰,次生α相的等轴化程度增高。(3)利用透射电镜观察连续变断面循环挤压以及热处理后试样的微观组织,揭示了组织的细化机理。结果表明,CVCE变形组织热处理时主要是以再结晶实现晶粒细化。(4)采用DEFORM软件对较优的变形工艺参数(850℃,6道次,5mm/s)进行温度场、应力场及应变场的模拟,变形过程中发生变形能和热能之间转换,随着变形道次的增加应变量不断累积,变形道次为6时,试样中间部位的累积应变量可达到5.83~7.20,且分布较为均匀。
[Abstract]:Grain refinement is one of the effective ways to improve the properties of metal materials. At present, there are still some problems in the preparation of fine-grained materials by large plastic deformation, such as the smaller size of the workpiece processed, the obvious texture tendency and so on. Continuous variable section cyclic extrusion (Continuous Variable Cross-section Recycled Extrusion,CVCE) is a new kind of large plastic deformation method for the preparation of large size bulk fine grain materials. Its operation is relatively simple, and its production efficiency is high, and it can realize the uniform control of the deformable body during the process of deformation. It is conducive to the realization of industrial production. In this paper, the TC11 alloy was deformed by continuous cyclic extrusion with variable cross section, and the material after deformation was treated by heat treatment. The effects of deformation parameters and heat treatment system on the microstructure and properties of the alloy were studied. The temperature field, stress field and strain field of a group of process parameters (850 鈩，
本文编号：2202776
[Abstract]:Grain refinement is one of the effective ways to improve the properties of metal materials. At present, there are still some problems in the preparation of fine-grained materials by large plastic deformation, such as the smaller size of the workpiece processed, the obvious texture tendency and so on. Continuous variable section cyclic extrusion (Continuous Variable Cross-section Recycled Extrusion,CVCE) is a new kind of large plastic deformation method for the preparation of large size bulk fine grain materials. Its operation is relatively simple, and its production efficiency is high, and it can realize the uniform control of the deformable body during the process of deformation. It is conducive to the realization of industrial production. In this paper, the TC11 alloy was deformed by continuous cyclic extrusion with variable cross section, and the material after deformation was treated by heat treatment. The effects of deformation parameters and heat treatment system on the microstructure and properties of the alloy were studied. The temperature field, stress field and strain field of a group of process parameters (850 鈩，
本文编号：2202776
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