电弧增材制造中应变场测量技术及固态相变的影响规律和机理

Distortion control is one of the application bottlenecks of metal additive manufacturing. The study of strain field evolution of component during manufacturing process is one of the key way to solve this problem. However, there are few measuring methods to measure the strain field evolution during additive manufacturing, currently. In addition, the effect and mechanism of solid phase transformation on the strain field evolution in wire arc additive manufacturing (WAAM) is unclear. The present study proposes a high-precision real-time measurement method of component strain field evolution during WAAM based on three-dimensional digital image correlation (3D DIC) technology. The strain field evolution during WAAM of heat-resistant steel with martensitic transformation is studied. The key process factor and control methods of strain concentration and large distortion of the component are proposed. The influence mechanism of martensitic transformation on the strain field evolution is revealed. The present research will provide effective research technology and theoretical support for the problem of distortion control of WAAM.

变形控制是金属增材制造的研究难点和应用瓶颈之一，制造过程中构件应变场演变研究是解决这一问题的关键途径。然而目前增材构件应变场演变试验研究手段匮乏，固态相变效应对电弧增材制造应变场演变的影响不清、机理不明。本项目提出基于三维DIC的电弧增材制造构件应变场高精度实时测量技术，研究含有马氏体相变的中合金耐热钢电弧增材制造应变场演变行为，提出造成构件应变集中和大变形的关键工艺因素及控制方法，揭示马氏体相变效应对构件应变场演变行为的影响机理。通过本项目研究，将为电弧增材制造变形控制问题提供有效的研究手段和理论支持。

针对变形控制的迫切研究需求，及马氏体相变影响应变场行为的科学问题，开展了马氏体钢电弧增材制造构件应变场演变行为及机理研究。基于三维DIC技术实现电弧增材制造构件表观应变场行为的准确测量，探究增材体表观应变场演变行为的影响规律，分析表观应变场演变数据中的马氏体相变特征信息及影响规律，揭示增材体在复杂热循环和马氏体相变作用下的应变场演变机理，探讨了影响构件变形的关键工艺因素及其影响机理。研究发现，基于DIC技术的电弧增材制造构件变形过程测量系统的测量精度不低于0.01 mm，建立的考虑马氏体相变的电弧增材制造构件应力变形有限元计算模型的计算结果与试验测量结果吻合良好，当层间冷却时间为90s时获得的单壁墙形状最接近矩形。本研究的意义一方面在于探索增材体的应变场演变监测技术及演变行为规律，另一方面在于揭示制造过程中增材体应变场演变内在成因和影响因素，为增材制造的变形监测与控制提供理论支持。