力—脉冲电流耦合作用下金属构件止裂机理及调控机制研究

Remanufacturing engineering is an effective way to realize energy saving and emission reduction and promote the development of circular economy. Pulse current is widely concerned as an effective method to crack-arrest, which is an extremely important subject in remanufacturing engineering. However, crack-arrest and regulation mechanism for metal component suing pulse current under stress state need to be further studied. In this project, the crack-arrest mechanism for metal component under the coupling effect of stress and pulse current is studied through the designed experiment platform. Based on the FEM subroutine, the gradient change of material performance with the temperature field is simulated. Moreover, the model of crack-arrest mechanism for metal component under the coupling effect of stress and pulse current is proposed to reveal crack propagation and crack-arrest mechanism with the action of pulse current under tensile stress state. It is helpful to explore the mechanism and model construction of crack-arrest by pulse current with multi-factor coupling effect. In addition, the method of constructing the J integral calculation model is proposed, and the quantitative evaluation method of the crack tip performance after crack-arrest is established based on the J integral. Furthermore, the variation of the crack tip performance with the pulse energy quantifies is revealed to explore control mechanism of pulse energy. Finally, the best crack-arrest result of metal components can be achieved through the control of pulse energy, which is scientific value and guidance to research and development for the application of crack-arrest using pulse current.

再制造工程是实现节能减排和促进循环经济发展的有效途径，裂纹止裂是再制造工程中极其重要的课题，脉冲电流作为一种有效的止裂方法得到广泛的关注，但是应力状态下金属构件的脉冲电流止裂机理和调控机制还亟待进一步研究。本项目通过设计的实验平台开展力—脉冲电流耦合作用下金属构件的止裂机理研究，基于有限元子程序实现材料性能随温度场梯度变化的模拟，构建力—脉冲电流耦合作用下金属构件的止裂模型，揭示拉应力状态下脉冲电流作用后裂纹的扩展及止裂机理，有助于探寻多因素耦合作用下脉冲电流止裂的机理研究和模型构建。并提出止裂后裂纹J积分计算模型的构建方法，基于J积分实现对止裂后裂纹尖端性能的定量评定，揭示止裂后裂纹尖端性能随脉冲能量的定量变化规律，探索止裂脉冲能量的调控机制，实现通过调控脉冲能量使金属构件达到最佳止裂效果，对研究和开发脉冲电流的止裂应用具有科学价值和指导作用。

本课题针对再制造过程中的裂纹止裂问题进行了深入的研究，通过揭示应力状态下金属构件的脉冲电流止裂机理和调控机制，有利于促进再制造工程的发展，从而实现节能减排和促进循环经济的发展。项目完成了力—脉冲电流耦合作用下金属构件的止裂机理研究，结合电-热-力多场耦合有限元模拟，从微观形貌以及组织性能方面综合分析了高压脉冲电流含裂纹金属材料试样止裂的效果，构建了力—脉冲电流耦合作用下金属构件的止裂模型。采用围线积分计算裂纹尖端应力强度因子，应用扩展有限元模拟裂纹尖端在升温过程中的裂纹扩展。量化了脉冲电流放电瞬间热压力场对裂纹扩展的抑制作用，证明了有最佳曲率半径的存在，应综合考虑裂纹增长量、裂纹钝化，建立评价脉冲电流止裂效果的方法，确定止裂所需的最佳脉冲能量，使构件达到最佳止裂效果。研究了脉冲电流止裂后奥氏体不锈钢止裂处的微观组织和局部腐蚀性能，实现了钝化后裂尖处材料的耐腐蚀性能的有效评价。