超声冲击强化焊接接头及金属表面强化研究进展

Research Progress of Ultrasonic Impact Treatment for Welded Joint and Metal Surface

工程机械零件及焊接结构在服役过程中常常因为表面发生磨损、腐蚀和疲劳断裂而失效,而失效形式与其表面加工质量、应力分布状态和表面性能等因素密切相关。超声冲击是一种利用超声波振动驱动冲击针高速撞击工件表面,使工件表面产生塑性变形和残余压应力的表面强化技术,具有效率高、加工精度高以及加工范围广等优势。概述了超声冲击处理技术在焊接接头处理、金属材料表面强化、激光熔覆–超声冲击复合处理以及超声冲击–化学处理复合强化等方面的研究现状及进展。在此基础上,重点综述了超声冲击处理Al、Mg合金及合金钢焊接接头残余应力、力学性能及抗疲劳性能的变化,归纳了传统金属材料以及新兴高熵合金表面超声冲击处理后的组织、微观亚结构及性能变化,总结了超声冲击对激光改性层组织性能的影响规律以及超声冲击预处理对离子渗氮/渗硫层形成及其性能的影响等。超声冲击处理明显降低了焊接接头的残余拉应力,有效提高其疲劳强度,使金属和涂层表面产生纳米化组织,显著提升材料的表面硬度、耐磨性能、耐蚀性能以及耐高温性能,从而延长工程构件的服役寿命。显然,超声冲击处理技术与表面涂层技术相结合,为工程零部件表面强化提供了新的思路。对于表面涂层,超声冲击能够在兼顾其塑韧性的前提下提升表面性能,获得更高的表面质量、更优异的耐蚀性能和耐磨性能,广泛应用在关键零部件的强化、修复、再制造等领域。另外,超声冲击层内细化的组织和大量的微观亚结构为后续化学处理提供了更多的扩散通道,起到了积极的促进作用。最后展望了超声冲击处理技术在工程结构件中的应用前景及发展方向,为其推广应用提供参考。

In engineering fields the construction machinery parts and the welded structures usually fail in practice due to surface wear,corrosion phenomenon and fatigue fracture phenomenon during their services,which makes a large amount of lost in industry production.It has been shown that the failure mechanism of metal surfaces is closely related to surface processing quality,stress distribution status and surface properties,and so on.As we know,ultrasonic impact treatment is a kind of surface strengthening technology,in which ultrasonic vibration are generated with a ultrasonic generator to drive the impact needle to impact the surface of work-piece at high speed,resulting in obvious plastic deformation as well as the generation of residual compressive stress.In addition,this technology possesses many advantages,such as high efficiency,high machining accuracy and wide machining range.In this paper,the research status and progress of ultrasonic impact treatment technology applied in welding joint treatment,surface strengthening of metal materials,laser cladding-ultrasonic impact composite treatment technology and ultrasonic impact-chemical treatment composite strengthening technology were summarized in general.On this basis,the change trend of residual stress distribution,mechanical properties and fatigue resistance of Al,Mg alloys and welded joints of alloy steels by ultrasonic impact treatment were summarized.In addition,the changes in the microstructures,substructures(such as dislocations,twins,and so on)and surface properties of traditional metal materials as well as new types of high entropy alloys after ultrasonic impact treatment were reviewed.Furthermore,the influence of ultrasonic impact treatment on microstructures and surface properties of laser surface modified layers was summarized and the effect of ultrasonic impact pre-treatment on the formation and surface properties of ion nitriding layer and ion sulphurizing layer was discussed.The results showed that ultrasonic impact treatment significantly reduced the residual tensile stress of the welded joints,effectively improved their fatigue strength,brought out nano-structures on the surfaces of metal and coatings,and significantly improved the surface hardness,wear resistance and corrosion resistance as well as high temperature resistance,so as to prolong the service life of engineering components.Obviously,the combination of ultrasonic impact treatment technology and surface coating technology provided a new idea for surface strengthening of engineering parts.For the surface strengthened layers,ultrasonic impact treatment was able to improve the surface properties dramatically on the premise of taking into account its plasticity and toughness,and bring out higher surface quality,better corrosion resistance and wear resistance.It was widely used in the fields of strengthening,repairing and re-manufacturing of key engineering parts in the engineering fields.Additionally,after ultrasonic impact treatment the refined structures in the ultrasonic impacted layer as well as a large number of microstructures provided more and more diffusion channels for subsequent chemical treatment,which played a positive role in promoting chemical treatment.Finally,the application prospect of ultrasonic impact treatment technology in engineering structural parts was prospected and the development direction of this technology was pointed in this article,all of which provided a reference for its popularization and application.