Linear friction welding of Ti–6Al–4V: Modelling and validation
Linear friction welding of Ti–6Al–4V: Modelling and validation
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DOI：
10.1016/j.actamat.2011.02.028
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发表时间：
2011-06
期刊：
影响因子：
9.4
通讯作者：
Raymond J. Turner;J. Gebelin;R. M. Ward;R. Reed
中科院分区：
文献类型：
--
作者：
Raymond J. Turner;J. Gebelin;R. M. Ward;R. Reed
线性摩擦焊接(LFW)过程--生产下一代民用航空发动机叶片盘所需的类型--使用数值和分析方法进行建模。为了进行模型验证和试验，利用中试装置对Ti-6Al-4V合金进行了实验研究。用热电偶对焊缝进行了测量，以减少过程中普遍存在的热传递效应。测量的翻转速率对关键工艺变量--振幅、频率和施加的压力--的敏感性与模型的预测一致。产生的闪光取决于振荡幅度与外加负载的比率；当这一比率较大时，会产生波纹形态。提出了一个分析模型，在该模型中，机械加工速率与闪光形成热平衡；在稳态时，预测热影响区(HAZ)的温度将随距离呈指数下降，而HAZ内的温度梯度将随着翻转速率的增加而增大，这与观测结果一致。通过考虑分析模型的形式和在LFW过程中发生的过程，提出了对于给定的顶锻速率，焊接温度随着压力的增加而降低。实验数据分析表明，绝热加热效率接近100%。
The linear friction welding (LFW) process – of the type required for the production of bladed discs for the next generation of civil aero-engines – is modelled using numerical and analytical methods. For model validation and testing, experimental work is carried out on the Ti–6Al–4V alloy using pilot-scale apparatus. Welds were instrumented with thermocouples to deduce the heat transfer effects prevalent in the process. The sensitivity of the measured rates of upset to the critical process variables – amplitude, frequency and the applied pressure – is shown to be consistent with the predictions of the modelling. The flash produced is dependent upon the ratio of oscillation amplitude to applied load; when this is large, a rippled morphology is produced. An analytical model of the process is proposed, in which the rate of mechanical working is balanced against the enthalpy associated with flash formation; at steady state, the temperature is predicted to decrease exponentially with distance in the heat-affected zone (HAZ), and the temperature gradient in the HAZ to increase as the upset rate increases, consistent with observation. By consideration of the form of the analytical model and the processes occurring during LFW it is suggested that, for a given upset rate, the weld temperature decreases as the pressure increases. Analysis of the experimental data indicates that the efficiency of adiabatic heating is close to 100%.