摘要
搅拌摩擦焊接过程中的产热、传热与塑性材料流动行为直接决定了焊接接头的组织演变及力学性能。对这些物理现象开展数值模拟研究,对于深入理解搅拌摩擦焊接过程的物理机制和优化焊接工艺具有重要意义。本文综述了搅拌摩擦焊接过程产热、传热与材料流动数值模拟的国内外研究现状,指出了存在的主要问题。介绍了作者课题组近年来针对这些问题所开展的研究工作。根据搅拌头-工件界面上的受力特点,研发出了黏着系数和摩擦因数的测试-计算法,为提高数值模拟的精度奠定了基础。建立了针对复杂截面形状搅拌针的搅拌摩擦焊接过程数学模型,数值分析了3种典型搅拌头情况下焊接过程中的产热率、温度分布和塑性流动行为。建立了包含下压、停留、焊接及冷却4个阶段的搅拌摩擦焊接全过程的传热-流动耦合模型,模拟了焊接过程各阶段的产热、温度场和塑性材料流动的演变情况。在此基础上,对搅拌摩擦焊接过程数值模拟领域未来的发展趋势进行了展望,提出了下一步的研究重点。
The heat generation, heat transfer and plasticized material flow in friction stir welding determine directly the microstructure evolution and mechanical properties of weld joints. Numerical simulation of these thermo-physical phenomena is of great significance for getting a deep insight into the underlying mechanisms and optimizing the process parameters of friction stir welding. This article reviews the progress status in numerical simulation of heat generation, heat transfer and plasticized material flow behaviors in friction stir welding, and outlines the unsolved problems. The research work targeting these issues, which has been conducted by the authors’ group, is introduced. According to the stress characteristics at the tool-workpiece interface, the expressions of sticking rate and friction coefficient are developed,and this measurement-calculation method lays foundation for improving the accuracy of numerical analysis. Through synthetically considering the characteristics of complex-shaped tools, a three dimensional model of friction stir welding process is established. Three types of tools are taken into consideration, i.e.,normal CT（conical-pin tool）, ST（conical-pin with 4 flats tool） and TT（conical-pin with 3 flats tool）. For thecases in application of these tools, the heat generation, temperature profile, and material flow velocity are analyzed quantitatively. A mathematical model for the whole friction stir welding process including plunge stage, dwell stage, welding stage, and cooling stage is established for numerical analysis of transient development in heat generation rate, temperature and material flow fields in each stages. Based on the status review, the trend in numerical simulation of frictions stir welding is outlooked, and the research focus for next step is proposed.
出处
《金属学报》
SCIE
EI
CAS
CSCD
北大核心
2018年第2期265-277,共13页
Acta Metallurgica Sinica
基金
国家自然科学基金项目No.51475272~~
关键词
搅拌摩擦焊接
产热
传热
材料流动
数值模拟
friction stir welding
heat generation
heat transfer
material flow
numerical simulation
