消除7136铝合金固溶热处理粗晶环的新方法:应变固溶  

A New Method for Eliminating Peripheral Coarse Grain Structure Formed in the Solution Treatment of 7136 Aluminum Alloy:Strain Solution

作　　者：赵帆 何颖 张志豪 ZHAO Fan;HE Ying;ZHANG Zhihao(Key Laboratory for Advanced Materials Processing(MOE),Institute for Advanced Materials and Technology,University of Science and Technology Beijing,Beijing 100083,China)

机构地区：[1]北京科技大学新材料技术研究院,材料先进制备技术教育部重点实验室,北京100083

出　　处：《材料导报》2021年第14期14079-14083,14088,共6页Materials Reports

基　　金：佛山市核心技术攻关项目(1920001000409);NSFC-辽宁联合基金(U1708251)。

摘　　要：固溶热处理粗晶环的新方法——应变固溶,即在进行双级固溶(450℃/2 h+470℃/4 h)前,在420℃时对试样施加拉伸应变并保温2 h。研究发现,随着应变固溶时应变量的增大,固溶处理后铝合金粗晶环深度逐渐减小,当应变量达到4.6%时,粗晶环完全消除。这一方法的机制是利用应变固溶在较低温度时消耗并释放形变储能,从而抑制固溶热处理过程中Al 3Zr相的熟化,调控铝合金的再结晶行为。TEM和EBSD分析显示,固溶热处理前经历了应变量为4.6%的应变固溶的样品,其边部再结晶比例仅为49.5%,远低于未经应变固溶直接进行热处理的样品(76.4%),并且再结晶晶粒正常长大形成细小等轴晶粒,使粗晶环得以消除。另外,应变固溶处理会导致型材峰值时效后的硬度有所降低,但降幅不大;同时试样心部仍保持较多的[111]晶向,即平行于挤压方向的织构。The peripheral coarse grain(PCG)structure is a kind of typical defect in the extruded high strength aluminum alloys.A new method which called strain solution,is capable of eliminating the PCG structure formed in the solution treatment of 7136 aluminum alloy.Before two-stage solution(450℃/2 h+470℃/4 h),the alloy samples were deformed to introduce various tensile strains at 420℃ and then kept at the same temperature for 2 h.It can be found in the two-stage solution-treated sample that the depth of PCG structure varied inversely with tensile strain introduced during strain solution,and that PGG could be eliminated when the strain introduced reached 4.6%.The strain solution consumes and releases the stored deformation energy at a relatively low temperature,and consequently,suppresses the coarsening of particles at the edge of extrusion during the two-stage solution treatment.As a result,the recrystallization behavior is regulated.This mechanism was supported by TEM and EBSD measurements of the sample which experienced strain-solution(4.6% strain)treatment prior to two-stage solution treatment,and the sample which was directly two-stage solution-treated:the former had a recrystallization volume fraction at the edge of 49.5%,fairly lower than that of the latter(76.4%),and also was spared from the generation of PGG structure for the growth of the recrystallized grains which formed fine equiaxial grains.In addition,the introduction of strain-solution treatment led to a slight reduction of material hardness,while a substantial amount of the [111]-oriented(i.e.parallel to the extrusion direction)grains were retained at the center of the sample.

关 键 词：粗晶环 组织缺陷 7系铝合金 挤压 固溶 再结晶 

分 类 号：TG379[金属学及工艺—金属压力加工]