前進(jìn)速率對(duì)攪拌摩擦加工ZK60鎂合金組織和力學(xué)性能的影響

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

對(duì)鑄態(tài)ZK60鎂合金進(jìn)行攪拌摩擦加工，在轉(zhuǎn)速為800r/min，前進(jìn)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(duì)其組織和力學(xué)性能進(jìn)行研究。研究結(jié)果表明：劇烈的塑性變形使攪拌區(qū)的晶粒相對(duì)于鑄態(tài)母材得到了明顯細(xì)化，隨著前進(jìn)速率的增加，攪拌區(qū)平均晶粒尺寸先減小后增大。攪拌區(qū)細(xì)晶組織的顯微硬度及抗拉強(qiáng)度相比于鑄態(tài)母材有所提高，而伸長(zhǎng)率顯著提高。在轉(zhuǎn)速為800r/min，前進(jìn)速率為100mm/min的加工條件下，攪拌區(qū)的晶粒最為細(xì)小均勻，其平均晶粒尺寸為6.9 μm，材料的硬度、抗拉強(qiáng)度和伸長(zhǎng)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.