脉冲电流处理技术作为一种新的材料处理技术,近年来被广泛应用于材料中残余应力的消除与调控。本文简要综述了残余应力的产生、危害及其传统控制手段,详细回顾了多种脉冲电流作用方式下的残余应力演变特征,并对各处理方式下的残余应力演化机理进行了简要讨论。结果表明,高能脉冲电流作用下,金属材料内部和表面的残余应力在极短的时间内(通常小于1 s)可以得到有效消除,消除率最高可达100%；电流密度越大,残余应力消除率越高,金属材料内部初始残余应力越大残余应力越容易得到消除。低能连续脉冲电流处理的实验结果则存在着残余应力变大、变小、不变等多种响应方式,其与材料类型和脉冲电流参数有重要关系。采用脉冲电流和外加应力耦合的处理方式对材料中的残余应力进行调控效果良好。在材料加工过程中耦合低能连续脉冲电流能够有效地在材料表面引入残余压应力,提高材料的抗疲劳和抗腐蚀性能。脉冲电流通过材料时产生锤击的电冲击技术,可以将材料表面的拉应力转化为压应力,从而提升材料的性能,此技术有效突破了高能脉冲电流消除残余应力能量要求过高的限制,并能实现工件服役现场直接定区域处理。脉冲电流处理消除残余应力的机理是：脉冲电流导致的Joule热效应和电致塑性效应促进位错运动,降低材料的流变应力,从而使材料可以在更低的应力水平上发生塑性变形,其中起关键作用的是电致塑性效应。脉冲电流导致的应力改变(热应力、箍缩效应、磁致伸缩效应、瞬时热膨胀应力)、外加应力(变形、冲击)和残余应力的联合作用构成了促进塑性变形的驱动力。

The generation of residual stress is unavoidable during the preparation and processing of metallic materials. This residual stress reduces the stability of material preparation and processing, particularly the surface tensile stress, which will reduce the fatigue and corrosion resistances of the material. Therefore, the effective regulation of the residual stress is generally required. However, traditional residual stress control methods, such as heat treatment, exhibits low efficiency because they are limited by material size and type. It is crucial to develop a new method for regulating residual stress that is green, low energy consumption, stable, effective, and applicable to various metallic materials. Pulsed electric current processing is a new material processing technology. It has been widely used in the elimination and control of residual stress in materials in the recent years. Herein, the generation, disadvantages, and traditional control methods of residual stress are briefly reviewed; the characteristics of residual stress under various pulsed electric current treatment modes are reviewed in detail; and the mechanism of residual stress under pulsed electric current is briefly discussed. Based on the obtained results, under the action of high energy pulsed electric current, the residual stress inside and on the surface of the metallic materials can be effectively eliminated in a very short period (approximately 1 s) and the maximum elimination rate can reach 100%. The higher the current density, the higher is the rate of residual stress elimination. Furthermore, the greater the initial residual stress in the material, it is simpler to eliminate residual stress. The experimental results of low energy continuous pulsed electric current treatment show that there are numerous types of response modes, such as increasing, decreasing, and unchanged residual stress, which are associated with the type of material and the pulse parameters. To control the residual stress in the material, the treatment method for coupling pulsed electric current and external stress is effective. Coupling low energy continuous pulsed electric current during material processing can effectively introduce residual compressive stress on the surface of the material and improve the fatigue and corrosion resistances of the material. The electrodynamic treatment technology, which produces hammering when the material is subjected to pulsed electric current, can transform the tensile stress on the material surface into compressive stress to improve the performance of the material. This effectively breaks through the high energy requirement of eliminating residual stress and allowing the workpiece directly in the setting regional area. Residual stress in pulsed electric current processing is removed via the following mechanism: Joule heating and pulsed electric current effects caused by pulsed electric current promote dislocation movement and reduce the flow stress of the material; therefore, the material can undergo plastic deformation at a low stress level, for which the pulsed electric current effect is crucial. The combined action of stress changes caused by pulsed electric current (thermal stress, pinch effect, magnetostrictive effect, and instantaneous thermal expansion stress), external stress (deformation and impact), and residual stress constitute the driving force to promote plastic deformation.