表面残余应力影响因素和调控技术的研究进展

Research Progress of Influencing Factors and Control Technologies on Surface Residual Stress

残余应力的存在在一定程度上影响了工件的疲劳寿命和抗腐蚀能力等,调控工件内部残余应力的分布在工程应用上具有很高的研究价值,合理调控应力能够有效抵抗工件表面的裂纹萌生,提高工件表面整体完整性。具体阐述了残余应力的概念和分类;分别从铣削、磨削和焊接角度归纳了传统加工过程中残余应力的产生机理及其对材料性能的影响;对相关残余应力检测技术的原理和优缺点进行论述;概述了残余应力有限元计算方法;综述了各种加工方法下,工艺参数对工件表面残余应力产生的影响;针对优化工艺参数调控残余应力无法满足工件的整体性能需求,归纳了时效法调控残余应力的机理;综述了能够进行应力调控的表面强化处理技术,包括机械作用下的孔挤压强化、超声振动磨削、喷丸工艺、超声滚压和激光冲击、能量外部输入下的高能声束调控技术、高能量密度脉冲电流和激光辐照应力调控技术。此外,针对单一表面强化处理技术调控残余应力的不足,概述了超声挤压-激光冲压、激光冲击-超声滚压以及激光冲击-喷丸等相关的复合表面强化工艺。最后,指出了表面强化处理技术处理复杂曲面,以及复合表面强化工艺是未来表面完整性加工的发展方向。

The residual stress influences the fatigue life and corrosion resistance of the workpiece to a certain extent, which is often ignored because of its poor intuition and difficult to detect. It has high research value in engineering application to regulate the distribution of residual stress in the workpiece. Reasonable regulation of stress can effectively resist the crack initiation on the workpiece surface and improve the overall integrity of the workpiece surface.The concept and classification of residual stress are described in detail. The residual stresses are classified from macroscopic and microscopic perspectives and their basic causes are described. The generation mechanism of residual stress in traditional machining process is summarized from the perspectives of milling, grinding and welding respectively.The influence of residual tensile stress and compressive stress on the material properties of the workpiece is mainly introduced through the position of residual tensile stress in the process of machining.Only by knowing the influence of residual stress on workpiece performance can the negative influence of residual tensile stress be reduced or residual compressive stress be rationally utilized.The principles of nondestructive testing(X-ray, magnetic, ultrasonic, curvature, Raman spectroscopy) and damage testing(mechanical, moire interference) are summarized, and the advantages and disadvantages of the testing methods are summarized. Based on the applicability of the detection method, the accurate stress value can be obtained by selecting the appropriate method.With the development of computer technology, a lot of research on the finite element model of residual stress has been carried out at home and abroad, which can save the cost and provide reference for the experiment. However,there is a lack of comprehensive consideration of various influencing factors.The influence of process parameters on the surface residual stress of workpiece under various processing methods was emphatically reviewed. Because regulating residual stress via optimizing process parameters cannot meet the overall performance requirements of the workpiece. The mechanism and application occasions of regulating residual stress by natural aging method, heat treatment aging method and vibration aging method are summarized. The surface strengthening technology which can control stress are reviewed, include under mechanical action ultrasonic vibration grinding, shot peening, ultrasonic rolling, laser shock;Under external energy input high-energy sound beam control technology, high-energy density pulse current and laser irradiation stress control technology. Energy input is used to eliminate tensile stress from the microscopic point of view. Through a certain technology, energy is input to the grain to increase the kinetic energy and potential energy of crystal atoms and break the unstable high-energy state of the original particles, thus releasing part of the residual stress. Mechanical strengthening belongs to macro control. Under the action of external force field, the workpiece surface produces certain elastic-plastic deformation, and the residual compressive stress is introduced into the surface of the workpiece. In addition, in view of the deficiency of single surface strengthening technology in residual stress control, the composite surface strengthening technologies such as ultrasonic extrusion-laser stamping, laser shock-ultrasonic rolling and laser shock-shot peening are summarized.Although attention has been paid to the important role of residual stress in machine parts manufacturing, engineers and technicians do not have a deep understanding of it.In the future, combined with process parameter optimization and stress control technology, the workpiece performance can be greatly improved.At the same time, the surface strengthening technology will develop towards the processing of complex surface and composite surface strengthening technology.