超声纳米晶体表面改性对304不锈钢显微组织和性能的影响  

Effect of ultrasonic nanocrystal surface modification on microstructure and properties of 304 stainless steel

作　　者：高乐 张宇[1] 叶一璇 彭兰 叶畅 GAO Le;ZHANG Yu;YE Yixuan;PENG Lan;YE Chang(School of Mechanical Science and Engineering,Huazhong University of Science and Technology,Wuhan 430074,China)

机构地区：[1]华中科技大学机械科学与工程学院,武汉430074

出　　处：《材料工程》2024年第8期142-149,共8页Journal of Materials Engineering

基　　金：国家自然科学基金资助项目(52075200);国家重点研发计划项目(2020YFA0714902)。

摘　　要：采用超声纳米晶体表面改性(ultrasonic nanocrystal surface modification, UNSM)技术对304不锈钢进行表面强化处理,研究UNSM对不锈钢微观组织和力学性能的影响。通过透射电子显微镜(TEM),电子背散射衍射(EBSD)等表征方法,分析处理前后304不锈钢的微观组织演变和塑性变形机制。利用白光干涉仪和显微硬度仪等手段,研究UNSM对材料表面粗糙度、显微硬度及残余应力的影响。结果表明:经UNSM处理后,304不锈钢表面发生严重塑性变形,导致位错密度增加,晶粒明显细化,并在近表面产生纳米细晶,形成约300μm深的硬化层。形变诱导奥氏体向马氏体转变,在表面引入约900 MPa的残余压应力,材料显微硬度从基材的238HV提高至511HV,表面完整性得到显著改善。The surface strengthening treatment of 304 stainless steel was carried out by using ultrasonic nanocrystal surface modification(UNSM)technology,and the effect of UNSM on the microstructure and mechanical performance of stainless steel was studied.The microstructure evolution and plastic deformation mechanism before and after UNSM treatment were analyzed by transmission electron microscopy(TEM),electron backscattered diffraction(EBSD)and other characterization methods.The effects of UNSM on surface roughness,microhardness and residual stress of materials were studied by using white light interferometry and microhardness testing.The results show that after UNSM treatment,304 stainless steel undergoes severe plastic deformation on the surface,resulting in an increase in dislocation density and significant grain refinement,and nanocrystals are generated on the near-surface region,forming a hardened layer about 300μm deep.The deformation induces austenite-to-martensite transformation and introduces the residual compressive stress of about 900 MPa on the surface.The microhardness of the material increases from 238HV to 511HV,and the surface integrity is significantly improved.

关 键 词：304不锈钢 超声纳米晶体表面改性(UNSM) 马氏体相变 残余压应力 

分 类 号：TG176[金属学及工艺—金属表面处理] TB31[金属学及工艺—金属学]