7075-T651铝合金表面纳米化处理及其强化机理  

Surface Nano-treatment of 7075-T651 Aluminum Alloy and its Strengthening Mechanism

作　　者：李莹 侯振国 钮旭晶 LI Ying;HOU Zhenguo;NIU Xujing(China Tangshan Locomotive and Rolling Limited Company,Tangshan 063035,China)

机构地区：[1]中车唐山机车车辆有限公司,河北唐山063035

出　　处：《电焊机》2022年第10期57-61,共5页Electric Welding Machine

摘　　要：通过表面机械滚压处理(SMRT)方法实现了7075-T651铝合金表面的纳米化。电子背散射衍射(EBSD)研究表明,SMRT后的试样表层形成了梯度纳米层:表层纳米晶粒层厚度约为50μm,平均晶粒尺寸约为200 nm;亚表层变形晶粒层厚度约为450μm,平均晶粒尺寸约为2μm,母材呈现出典型的轧制晶粒特征,平均晶粒尺寸约为5μm。拉伸试验结果表明,SMRT后试样的强度得到了显著提高,塑韧性也没有明显下降。通过SMRT在材料的表层引入了梯度纳米结构,这种特殊结构具有较为优秀的强度和塑性的匹配,是力学性能提升的主要原因。The surface nano-treatment of 7075-T651 aluminum alloy was realized by surface mechanical rolling treatment(SMRT) method. Electron backscatter diffraction(EBSD) results show that a 500 μm thick gradient nano-layer is formed on the surface of SMRT sample, the thickness of the surface nano-crystal layer is about 50 μm and the average grain size is about 200 nm. The thickness of the subsurface deformation grain layer is about 450 μm, and the average grain size is about 2 μm. The base metal shows typical rolling grain characteristics, and the average grain size is about 5 μm. The tensile test results show that the tensile strength, yield strength and elongation of the original 7075-T651 aluminum alloy are 545 MPa,506 MPa and 17.3% respectively. After SMRT, the tensile strength, yield strength and elongation are 620 MPa, 536 MPa and 13.4% respectively. The strength of the sample significantly improves, and the toughness does not significantly decrease.Gradient nanostructures are introduced into the surface layer of the material by SMRT. This special structure has excellent matching of strength and plasticity, which is the main reason for the improvement of mechanical properties.

关 键 词：7075铝合金 梯度纳米结构 表面机械滚压处理 表面纳米化处理 

分 类 号：TG453.9[金属学及工艺—焊接]