不同热处理条件下激光冲击AZ31镁合金的组织与性能研究

发布时间：2018-06-12 20:17

  本文选题：AZ31镁合金 + LSP　； 参考：《河南科技大学》2015年硕士论文

【摘要】：镁合金是轻质的结构金属材料,具有比强度和比刚度高、阻尼性能好、导热性好、屏蔽性好、易回收等一系列的优良性能,有着广阔的应用前景,目前已广泛应用于航空航天业、汽车工业、电子制造等领域。但是镁合金在力学性能上的局限性及耐腐蚀性能差等严重制约了其广泛的应用。本文利用激光冲击强化(Laser Shock Processing,LSP)技术研究了AZ31镁合金在高速冲击作用下的组织和性能变化,同时也分析了退火处理对激光冲击AZ31镁合金组织和性能的影响,从而提高其综合性能及使用价值,具有理论和现实意义。对时效处理后的镁合金进行激光冲击强化处理。激光冲击处理后AZ31镁合金试样的表层微观结构以高密度位错缠结为主,表层硬度为140HV,较冲击前提高了127%;试样的抗拉强度为305MPa,提高了21%;断裂延伸率提高了16%,激光冲击处理后材料的强度与韧性均得到明显提高且试样的自腐蚀电位较冲击前正移约880 mV,自腐蚀电流也明显降低,耐蚀性能显著提高。对激光冲击处理后的AZ31镁合金进行不同时间和温度的退火处理,经过350℃×30min退火处理后,镁合金的电极电位正移,自腐蚀电位达到-583mV,较冲击前正移了992mV,较冲击后正移了103mV,自腐蚀电流密度比冲击后降低了两个数量级,耐蚀性能得到明显提高;随着退火温度的升高及退火时间的延长,合金的硬度逐渐降低;在相同的退火时间(30min)条件下,抗拉强度及延伸率在200℃~350℃温度区间内,随着温度的升高逐渐增加,在400℃退火后迅速降低;在相同的退火温度(350℃)条件下,随着时间的延长抗拉强度逐步降低,伸长率先略有增加然后降低;最佳的退火温度及时间为350℃×30min,抗拉强度和断裂延伸率分别达到342MPa及18%。不同的退火工艺对激光冲击后合金的断口形貌有明显影响,在350℃×30min退火后断口呈现一定的韧性特征。经过适当的退火处理后试样表层晶粒得到细化,在350℃×30min退火处理后试样局部形成纳米晶。
[Abstract]:Magnesium alloy is a light structural metal material with high specific strength and stiffness, good damping property, good thermal conductivity, good shielding property, easy recovery and a series of excellent properties, so it has a broad application prospect. At present, it has been widely used in aerospace industry, automobile industry, electronic manufacturing and other fields. However, the limitation of mechanical properties and poor corrosion resistance of magnesium alloys restrict their wide application. In this paper, the microstructure and properties of AZ31 magnesium alloy under high speed impact were studied by laser shock hardening laser processing technique, and the effect of annealing on the microstructure and properties of AZ31 magnesium alloy was also analyzed. In order to improve its comprehensive performance and use value, it has theoretical and practical significance. The aging magnesium alloy was strengthened by laser impact. The microstructure of surface layer of AZ31 magnesium alloy treated by laser shock is mainly high density dislocation entanglement. The hardness of the surface layer is 140 HVV, which is 12775 higher than that before the impact, the tensile strength of the sample is 305 MPA, the tensile strength of the sample increases 21%, the elongation at break increases 16%, the strength and toughness of the material after laser shock treatment are obviously improved and the self-corrosion potential of the sample is higher than that of the impact. The forward shift is about 880mV, and the corrosion current decreases obviously. The corrosion resistance is greatly improved. AZ31 magnesium alloy after laser shock treatment was annealed at different time and temperature. After 350 鈩，

本文编号：2010932