Grain Refinement of Al-Mg alloy by Hydrogenation Treatment and Its mechanism Analysis

晶粒细化是提高材料强度和出现超塑性行为的一种方法。本研究表明，在5083AI （AI-Mg）合金中，利用高温吸氢和脱氢等特性，在加工过程中施加极大的塑性应变，可以获得这种细晶粒的微观组织。该处理得到的氢化物沉淀MgH_2作为位错堆积源更有利于在合金中形成高密度位错结构。研究结果如下：2001 ~ 20011：在773K下加氢处理14。4k，在0以下的氢大气中。4 mpa。对加氢后的试样进行了重冷轧，还原率为90%，通过x射线衍射分析和透射电镜观察确定了氢化物的存在，诱导氢含量约为107×10…More ^2质量%。然后，对其进行热处理，在盐浴中快速再结晶，得到晶粒细的材料。最后将材料在523K真空(0。1Pa)脱氢30hr。残余氢含量为0。9×10 ^ 2质量%。氢化后的样品显示出波纹状的变形痕迹，以防止容易变形，并显示出更细的晶粒结构(2)。5米)。屈服强度和抗拉强度提高1以上。与未氢化的样品相比增加了5倍。通过x射线衍射分析和透射电镜观察，确定了氢化物的存在。诱导氢含量越高，晶粒尺寸越细。2001 ~ 20021：对于氢化试样的超塑性行为，在625K和5×10^3 s^1应变速率下伸长率约为300%。试样的疲劳强度为1。比未氢化样品高8倍。然而，在腐蚀试验中，这些样品并没有显示出显著的改善。少

The grain refinement is noticed, as method to enhance the strength of materials and to be appeared the superplasticity behavior. The subject of this study has shown that, in 5083AI (AI-Mg) alloy, this microstructure with fine grain size can be achieved by imposing extremely large plastic strains during work processing using characteristic properties such as hydrogen absorption and dehydrogenation at high temperature. Hydride precipitations MgH_2 obtained in this treatment were more useful to develop the high-density dislocation structure in alloy as dislocation pileup sources.The following results of this study were obtained :2001〜20011 : Hydrogenation treatment was carried out in 773K for 14. 4ks and in hydrogen atmosphere under 0. 4MPa. The hydrogenated samples were carried out heavy cold rolling with the 90% reduction ratio An existence of hydrides was determined by an X-ray diffraction analysis and TEM observation using tritium technique An induced hydrogen content was about 107×10 … More ^2 mass%. Then, to obtain the fine grain sized material, heat treatment was performed to do rapid recrystallization in salt bath. The materials were finally heated at 523K in vacuum (0. 1Pa) for dehydrogenation for 30hr. The residual hydrogen content was 0. 9×10^2 mass%. The hydrogenated samples indicates wavy deformation traces to be prevented easy deformation and shows more fine grain structure (2. 5 u m). Yield strength and tensile strength increased more than 1. 5times in comparison with that of non-hydrogenated specimen.2 : An existence of hydrides was determined by an x-ray diffraction analysis and TEM observation using tritium technique. The grain size is finer with induced hydrogen content.2001〜20021 : For superplasticity behavior of hydrogenated specimen, elongation was about 300% at 625K and 5×10^3 s^1 strain rate. The fatigue strength of these samples was 1. 8times higher than that of non-hydrogenated samples. However, in corrosion test, these samples did not indicate remarkable improvement. Less