超声滚压对45钢微观组织和力学性能的影响  

Effect of Ultrasonic Rolling on Microstructure and Mechanical Properties of 45 Steel

作　　者：许全军 龚宝明[1,2] 刘秀国[1,2] 邓彩艳[1,2] 王东坡[1,2] XU Quan-jun;GONG Bao-ming;LIU Xiu-guo;DENG Cai-yan;WANG Dong-po(a.School of Materials Science and Engineering,b.Tianjin Key Laboratory of Advanced Joining Technology,Tianjin 300350,China)

机构地区：[1]天津大学材料科学与工程学院,天津300350 [2]天津大学天津市现代技术连接重点实验室,天津300350

出　　处：《表面技术》2022年第1期339-347,共9页Surface Technology

基　　金：国家自然科学基金(51771135)。

摘　　要：目的提高45钢的表面完整性,研究超声表面滚压加工(Ultrasonic Surface Rolling Processing,USRP)技术对45钢微观梯度结构和力学性能的影响。方法通过USRP技术,在材料表层制备出微观梯度结构,并对试样梯度结构组织进行金相、SEM、EBSD、表面粗糙度以及显微硬度分析。最后,考虑到尺度效应的影响,采用应变梯度理论修正的仪器化压痕法,对试样表层组织的梯度力学性能进行分析。结果试样表层形成120μm厚的取向各异的细小晶粒组织,晶粒尺寸形成了梯度变化,距离表层10μm区域内的平均晶粒尺寸可以达到360 nm。材料表层组织的大小角度晶界数量明显增多,且随加工遍数的增加而明显增加。试样的表面粗糙度降低至纳米级,比原始粗糙度降低了96.7%,表面显微硬度提高了55.1%。根据塑性变形程度,将表层微结构分为强变形区、微变形区和未影响区3个区域。强变形区、微变形区的厚度随着处理遍数的增加而增加,塑性变形层厚度最高达320μm。结论试样表层形成了一定厚度的细小晶粒组织,试样表面粗糙度和显微硬度均有明显改善。试样表层的弹性和塑性性能均体现出明显的梯度变化,其中弹性模量提高了1.67倍,屈服强度提高了83.3%,加工硬化指数降低了68.3%,在改善材料的抗疲劳和腐蚀性能方面十分有效。To improve the surface integrity,the effects of Ultrasonic Surface Rolling Processing(USRP)technology on the micro-gradient structure and mechanical properties of 45 steel is studied.The micro-gradient structure induced by USPR was analyzed by optical microscope(OM),scanning electron microscope(SEM)and electron back scattering diffraction(EBSD).Besides,the change of surface roughness and microhardness after USPR were also investigated.Finally,considering the scale effect,the instrumented indentation method modified by the strain gradient theory was used to analyze the gradient mechanical properties of the treated 45 steel.The results showed that a zone containing fine grains of different orientations was formed in the surface layer of the specimen with the depth of 120μm.The grain size varies in a gradient,and the average grain size in the region of 10μm from the surface layer can reach 360 nm.The number of small and large angular grain boundaries in the surface layer of the specimen increased significantly.The surface roughness of the specimen was reduced to the nanometer level,which was 96.7%lower than the original roughness,and the surface microhardness was increased by up to 55.1%.According to the degree of plastic deformation,the surface microstructure was divided into three areas:strongly deformed area,micro-deformed area and unaffected area.The depth of strongly deformed area and micro-deformed area increased with the number of processing passes,and the depth of plastic deformed layer was up to 320μm.Both the elastic and plastic properties of the surface layer underwent significant gradient changes,with the elastic modulus increasing by up to 1.67 times,the yield strength increasing by up to 83.3%and the work hardening index decreasing by up to 68.3%,which are effective in improving the fatigue and corrosion resistance of the material.

关 键 词：表层微结构 超声表面滚压处理 纳米压痕法 梯度力学性能 显微硬度 

分 类 号：TG142.1[一般工业技术—材料科学与工程]