液氮冷却FSP对AZ31镁合金材料力学性能的影响  

Effect of FSP Coupled with Liquid Nitrogen Cooling on Mechanical Properties of AZ31 Alloy

作　　者：刘守法[1] 薛飞[2] 李明珠[1] 李春风[3] 吴松林[1] 

机构地区：[1]西京学院机械工程学院,陕西西安710123 [2]永城职业学院机电工程系,河南永城476600 [3]承德石油高等专科学校工业中心,河北承德067000

出　　处：《热加工工艺》2015年第11期58-61,共4页Hot Working Technology

基　　金：陕西省教育厅科研基金资助项目(11JK0880)

摘　　要：利用液氮冷却装置减少了搅拌摩擦加工(FSP)过程中的热输入,采用SEM、显微硬度仪和试样拉伸设备对搅拌区显微组织和力学性能进行了测试分析。研究表明:通过液氮冷却作用减小热输入、减小搅拌头转速和增加搅拌摩擦道次均有利于减小搅拌区晶粒尺寸。液氮冷却条件下,搅拌头转速和进给速度分别为1000 r/min和37 mm/min时,两道次加工得到的搅拌区晶粒平均尺寸减小至100 nm左右,同时搅拌区硬度提高为原材料的2.7倍。液氮冷却环境FSP试样的屈服强度、抗拉强度和伸长率分别是自然冷却环境FSP试样的1.39、1.35和1.31倍。强度最大试样断口处分布着大量微米级韧窝和少量解理面,呈韧性断裂为主的混合断裂特征。Heat input during friction stir processing（FSP） was reduced by liquid nitrogen cooling equipment. The microstructure and mechanical properties of the samples were investigated by SEM, microhardness tester and specimen tensile equipment. The results show that the decrease of rotation speed, the increase of FSP pass and the decrease of heat input by liquid nitrogen cooling are all beneficial to grain refinement. Under the rotation speed of 1000 r·min-1 and travel speed of 37mm·min-1, two-pass FSP coupled with liquid nitrogen cooling could reduce the mean grain size to about 100 nm, which can improve the microhardness to 2.7 times the as received material. The yield strength, tensile strength and elongation of the FSP samples prepared under liquid nitrogen cooling condition is 1.39 times, 1.35 times and 1.31 times the FSP samples prepared without cooling equipment respectively. There are plenty of micron-sized dimples and small amount of cleavage plane on the fracture surface of the sample with maximum tensile strength, which exhibits mixed-rupture characteristics with ductile fracture dominated.

关 键 词：液氮冷却 搅拌摩擦加工 显微硬度 力学性能 混合断裂特征 

分 类 号：TG156[金属学及工艺—热处理]