表面渗铝镁合金的轧制组织与性能

Microstructure and properties on surface of aluminizing-modification magnesium alloy in rolling

引入"固态扩渗+轧制"的表面改性方式,即在研究镁合金薄板表面改性方法及工艺的基础上,采用固态粉末包覆热扩渗的方法,对AZ31镁合金薄板进行表面改性处理,获得研究目标材料;借助有限元软件Ls-DYNA模拟其冷轧过程,获得最优的轧制工艺参数并进行轧制实验,通过X-射线衍射(XRD)、金相显微镜、布氏硬度测量计、往复式摩擦磨损试验机和Corr Test腐蚀电化学测试系统检测材料表面的组织与性能。结果表明:轧制变形后的表面组织晶粒更加细小、均匀;耐磨性有所改善,表面硬度由HB 61.4提高至HB 63.5,摩擦因数由0.52变为0.6,表面摩擦磨损质量损失由0.33 mg降低至0.26 mg;表面耐腐蚀性能显著提高,其开路电位由-1.594 V变为-1.574 V,自腐蚀电位由-1.574 V变为-1.38 V,自腐蚀电流密度由6.2×10-3 m A/cm2变为7.0×10-4 m A/cm2。

In order to obtain the target material for the present investigtion, the new surface modification of ＂solid diffusion＋rolling＂ was introduced. It was on the basis of studying the surface modification and the technology of AZ31 magnesium alloy sheet, and then the method of solid diffusion was applied to deal with the sheet. After that, by using the optimum rolling technology parameters which got from the cold rolling simulation by the finite software of Ls-DYNA to conduct the rolling test. Finally after the test, the X-ray diffraction （XRD）, metallographic microscope, Brinell hardness tester, reciprocating friction ＆wear tester and Corr Test corrosion electro-chemistry test system were used to analyze the surface organization and performance of the target material. The results show that the grain structure of the surface is finer and more uniform after the rolling deformation and the abrasion resistance is greatly improved, which shows that the surface hardness increases from HB 61.4 to HB 63.5, the friction coefficient changes from 0.52 to 0.6 and the friction wear mass loss of the surface decreases from 0.33 mg to 0.26 mg. Besides, the anti-corrosion properties of the surface is also greatly improved, which shows that the open-circuit potential changes from -1.594 V to -1.574 V, the free corrosion potential changes from -1.574 V to -1.38 V and the free corrosion current density changes from 6.2 × 10-3 mA/cm2 to 7.0 × 10-4 mA/cm2.