Friction stir welding(FSW) is a promising welding process that can join age hardenable aluminium alloys with high joint efficiency. However,the thermal cycles experienced by the material to be joined during FSW result...Friction stir welding(FSW) is a promising welding process that can join age hardenable aluminium alloys with high joint efficiency. However,the thermal cycles experienced by the material to be joined during FSW resulted in the deterioration of mechanical properties due to the coarsening and dissolution of strengthening precipitates in the thermo-mechanical affected zone(TMAZ) and heat affected zone(HAZ). Under water friction stir welding(UWFSW) is a variant of FSW process which can maintain low heat input as well as constant heat input along the weld line. The heat conduction and dissipation during UWFSW controls the width of TMAZ and HAZ and also improves the joint properties. In this investigation, an attempt has been made to evaluate the mechanical properties and microstructural characteristics of AA2519-T87 aluminium alloy joints made by FSW and UWFSW processes. Finite element analysis has been used to estimate the temperature distribution and width of TMAZ region in both the joints and the results have been compared with experimental results and subsequently correlated with mechanical properties.? 2016 China Ordnance Society. Production and hosting by Elsevier B.V. All rights reserved.展开更多
目的探究在304LN不锈钢表面上激光沉积Stellite 6合金过程中的多元素传输机制。方法采用流体体积法VOF(Volume of Fluid),建立气-液两相传热传质激光沉积模型。模型中使用改进VOF法对熔池表面进行追踪,结合多组分传输模型与熔凝杠杆原则...目的探究在304LN不锈钢表面上激光沉积Stellite 6合金过程中的多元素传输机制。方法采用流体体积法VOF(Volume of Fluid),建立气-液两相传热传质激光沉积模型。模型中使用改进VOF法对熔池表面进行追踪,结合多组分传输模型与熔凝杠杆原则(Lever Rule),对异质材料熔覆界面的多元素传输进行模拟,采用扫描电子显微镜(SEM)与能谱仪(EDS)观察组织结构和元素分布,对比模拟结果分析多组沉积层宏观形貌和元素分布特征。结果沉积过程中,熔池的流动与材料导热对温度的传输起着重要作用,前端对流不断地将已熔化的基材金属运输至熔池中部,后端对流则将卷积的Fe元素和Co元素进一步混合。最终沉积层的宏观形貌平均误差为2.67%,主要元素Fe、Co、Cr的质量分数误差分别为0.64%、1.27%、0.31%。结论Fe元素浓度整体区域分布相对均匀,但在沉积层底部,Fe元素浓度迅速升高,Co元素浓度随沉积深度加深逐渐降低,Cr元素在沉积层中部富集的分布特性。该优化后的模型可以准确模拟异质合金沉积过程中的温度场、流场与质量传输过程。展开更多
基金the financial support of the Directorate of Extramural Research & Intellectual Property Rights (ER&IPR)Defense Research Development Organization (DRDO)New Delhi through a R&D project no. DRDO-ERIPER/ERIP/ER/0903821/M/01/1404 to carry out this investigation
文摘Friction stir welding(FSW) is a promising welding process that can join age hardenable aluminium alloys with high joint efficiency. However,the thermal cycles experienced by the material to be joined during FSW resulted in the deterioration of mechanical properties due to the coarsening and dissolution of strengthening precipitates in the thermo-mechanical affected zone(TMAZ) and heat affected zone(HAZ). Under water friction stir welding(UWFSW) is a variant of FSW process which can maintain low heat input as well as constant heat input along the weld line. The heat conduction and dissipation during UWFSW controls the width of TMAZ and HAZ and also improves the joint properties. In this investigation, an attempt has been made to evaluate the mechanical properties and microstructural characteristics of AA2519-T87 aluminium alloy joints made by FSW and UWFSW processes. Finite element analysis has been used to estimate the temperature distribution and width of TMAZ region in both the joints and the results have been compared with experimental results and subsequently correlated with mechanical properties.? 2016 China Ordnance Society. Production and hosting by Elsevier B.V. All rights reserved.
文摘目的探究在304LN不锈钢表面上激光沉积Stellite 6合金过程中的多元素传输机制。方法采用流体体积法VOF(Volume of Fluid),建立气-液两相传热传质激光沉积模型。模型中使用改进VOF法对熔池表面进行追踪,结合多组分传输模型与熔凝杠杆原则(Lever Rule),对异质材料熔覆界面的多元素传输进行模拟,采用扫描电子显微镜(SEM)与能谱仪(EDS)观察组织结构和元素分布,对比模拟结果分析多组沉积层宏观形貌和元素分布特征。结果沉积过程中,熔池的流动与材料导热对温度的传输起着重要作用,前端对流不断地将已熔化的基材金属运输至熔池中部,后端对流则将卷积的Fe元素和Co元素进一步混合。最终沉积层的宏观形貌平均误差为2.67%,主要元素Fe、Co、Cr的质量分数误差分别为0.64%、1.27%、0.31%。结论Fe元素浓度整体区域分布相对均匀,但在沉积层底部,Fe元素浓度迅速升高,Co元素浓度随沉积深度加深逐渐降低,Cr元素在沉积层中部富集的分布特性。该优化后的模型可以准确模拟异质合金沉积过程中的温度场、流场与质量传输过程。
