Effects of different friction stir welding conditions on the microstructure and mechanical properties of copper plates

Friction stir welding is a new and innovative welding method used to fuse materials. In this welding method, the heat generated by friction and plastic flow causes significant changes in the microstructure of the material, which leads to local changes in the mechanical properties of the weld. In this study, the effects of various welding parameters such as the rotational and traverse speeds of the tool on the microstructural and mechanical properties of copper plates were investigated; additionally, Charpy tests were performed on copper plates for the first time. Also, the effect of the number of welding passes on the aforementioned properties has not been investigated in previous studies. The results indicated that better welds with superior properties are produced when less heat is transferred to the workpiece during the welding process. It was also found that although the properties of the stir zone improved with an increasing number of weld passes, the properties of its weakest zone, the heat-affected zone, deteriorated.     

半固态搅拌摩擦焊温度场分析及组织验证

为避免由材料流动不足而导致的焊接缺陷以及降低焊接过程中的作用力,提出了半固态搅拌摩擦焊. 本文以2024-T3铝合金为研究对象,进行了焊接过程中温度及显微组织分析. 温度的模拟及测量结果表明:当搅拌头的旋转速度为1600r·min-1、焊接速度为150mm/min时,稳态时焊核区的温度峰值达到了518℃,超过了焊材的固相线. 空冷条件下常规搅拌摩擦焊与水冷条件下的半固态搅拌摩擦焊焊核区的显微组织对比结果表明,利用搅拌头摩擦产热的方法可使搅拌区呈现液态金属母液中均匀悬浮着近似球形晶粒的半固态组织.      

粉煤灰颗粒增强铝基复合材料的研究

采用搅拌铸造法制备粉煤灰增强铝基复合材料·粉煤灰颗粒大多为球形,密度为2 75g/cm3,颗粒直径主要集中在5～60μm,主要成分为SiO2、Al2O3、Fe2O3,三者质量分数总和超过85%·SEM分析表明铝基粉煤灰复合材料中存在着颗粒团聚,并有气孔产生·将制备的复合材料与6061合金就磨损、拉伸强度性能进行对比试验·试验结果表明:该复合材料在常温下抗拉强度变差,而耐磨性与6061合金相比提高20倍以上·     

基于双热源的搅拌摩擦焊热交换过程仿真

搅拌摩擦焊是轻金属连接的创新工艺.针对铝合金板AA2024-T3对接焊,建立双热源数值计算模型,综合考虑搅拌轴肩转动摩擦生热和搅拌头塑变剪切生热.通过ANSYS开发实现瞬态移动热交换有限元仿真,获得全程三维温度场分布.仿真结果与英国剑桥大学标准实验数据吻合良好,表明仿真模型可行,仿真结果合理,有助于进一步实现搅拌摩擦焊热-应力交互耦合仿真.     

自制吸附萃取搅拌棒结合气相色谱嗅觉计、 气质联用仪分析肉味香精呈香组分

采用自制吸附萃取搅拌棒对肉味香精呈香组分进行提取,利用热脱附仪进样,结合气相色谱嗅觉计联用(GC/O)、气质联用(GC/MS)双重定性方式,令组分富集率更高,且检测结果可以更加真实、客观地反映出香精的香气组成;为高级香精的调配及仿香工作提供重要依据.实验仪器采用在色谱柱出口安装"石英三通"进行1∶1分流,样品被同时引入质谱和嗅觉计,避免了单一定性方法存在的不足.其中,两种方法共同检出的物质31种,仅GC/O检出的物质24种,仅GC/MS检出的物质26种.     

6061-T6铝合金薄板的搅拌摩擦焊接

采用搅拌摩擦焊(FSW)技术对1mm厚6061-T6铝合金薄板进行了对接. 研究了焊接工艺参数的范围,实验测试了焊接接头的强度、硬度和延伸率,利用金相显微镜、扫描电镜和透射电镜分析了接头的微观组织. 结果表明:对于1mm厚度6061-T6铝合金,FSW的最优工艺参数为旋转速度1800r·min-1,焊接速度1000mm·min-1;在此参数下,接头的硬度值达到母材的80%左右,抗拉强度达到母材的103%,延伸率达到母材的54%;接头的力学性能与微观结构相符.     

搅拌摩擦焊、搅拌振动摩擦焊和钨极惰性气体焊接AA6061-T6接头的组织和力学特性对比研究

This study compared the microstructure and mechanical characteristics of AA6061-T6 joints produced using friction stir welding (FSW), friction stir vibration welding (FSVW), and tungsten inert gas welding (TIG). FSVW is a modified version of FSW wherein the joining specimens are vibrated normal to the welding line during FSW. The results indicated that the weld region grains for FSVW and FSW were equiaxed and were smaller than the grains for TIG. In addition, the weld region grains for FSVW were finer compared with those for FSW. Results also showed that the strength, hardness, and toughness values of the joints produced by FSVW were higher than those of the other joints produced by FSW and TIG. The vibration during FSW enhanced dynamic recrystallization, which led to the development of finer grains. The weld efficiency of FSVW was approximately 81%, whereas those of FSW and TIG were approximately 74% and 67%, respectively.     

搅拌摩擦焊工艺参数对超薄铝合金板/高强钢搭接焊接头组织及性能的影响

采用复合式搅拌头对0.7 mm厚6010铝合金板和2.0 mm厚DP600钢板进行搅拌摩擦搭接焊,在不磨损搅拌头的同时获得了性能优良的焊接接头。研究了不同焊接工艺参数对铝合金/高强钢焊接接头界面结构及力学性能的影响。结果表明,在搅拌针未进入钢板的情况下,顶锻力是搅拌摩擦焊过程中的关键参数,存在一个实现铝合金/高强钢异种材料搅拌摩擦搭接焊的最小顶锻力。在恒定顶锻力5.0 kN,转速1 200 r/min的焊接条件下得到了最佳性能的焊接接头,拉伸强度达到260 MPa,且断裂发生在铝合金母材区。铝合金/高强钢界面存在一层厚2.0 μm的过渡层。     

搅拌铸造法制备石墨烯增强铝基复合材料的组织和力学性能研究

石墨烯增强铝基复合材料满足轻量化用材的同时兼具良好的力学性能,是一种极具应用前景的复合材料。通过粉末混合、压坯和热还原,制备了含石墨烯的预制块,并将其作为中间体在搅拌铸造过程中加入,成功制备了石墨烯增强铝基复合材料。通过扫描电子显微镜、拉曼光谱、X射线衍射仪等表征了复合材料的微观组织结构;通过力学性能测试,研究了石墨烯含量对复合材料力学性能的影响。表征结果表明,搅拌铸造法制备的石墨烯增强铝基复合材料中石墨烯结构完整,复合材料的晶粒得到明显细化。拉伸试验表明,石墨烯质量分数为0.4%的铝基复合材料的综合力学性能最佳,抗拉强度、屈服强度和维氏硬度分别较同条件下制备的纯铝提高了55%、47%和63%。断裂机制研究结果表明,随着石墨烯含量的增加,复合材料由韧性断裂转变为脆性断裂。