前進速率對攪拌摩擦加工ZK60鎂合金組織和力學性能的影響

前進速率對攪拌摩擦加工ZK60鎂合金組織和力學性能的影響Influence of Processing Speed on Microstructure and Mechanical Properties of ZK60 Magnesium Alloy Prepared by Friction Stir Processing

對鑄態ZK60鎂合金進行攪拌摩擦加工，在轉速為800r/min，前進速率為50~200mm/min的條件下，獲得表面平整、無宏觀缺陷的材料，并對其組織和力學性能進行研究。研究結果表明：劇烈的塑性變形使攪拌區的晶粒相對于鑄態母材得到了明顯細化，隨著前進速率的增加，攪拌區平均晶粒尺寸先減小后增大。攪拌區細晶組織的顯微硬度及抗拉強度相比于鑄態母材有所提高，而伸長率顯著提高。在轉速為800r/min，前進速率為100mm/min的加工條件下，攪拌區的晶粒最為細小均勻，其平均晶粒尺寸為6.9 μm，材料的硬度、抗拉強度和伸長率分別為70.1HV，276 MPa和31.6%。

ZK60 casting magnesium alloy was subjected to friction stir processing (FSP). Defect-free joints could be obtained under a range of processing speeds (50-200 mm/min) at a constant rotation rate of 800 r/min, and microstructures and mechanical properties of the experimental materials were investigated. The results show that the coarse grains in base material are changed into fine equiaxed grains in stir zone after FSP. With the increas of processing speed, the mean grain size decreases firstly and then increases. The microhardness and tensile strength of stir zone increase compared with the base material, and the elongation increases significantly due to its fine and uniform microstructure of the specimen. The optimum properties are obtained in the specimen prepared at the processing speed of 100 mm/min, the average grain size of the specimen is 6.9 μm, and the microhardness, tensile strength and elongation are 70.1HV, 276 MPa and 31.6% respectively.