摘要
使用半径为500μm的球形氧化锆陶瓷压头对3种高分子和20种金属材料在渐进载荷下进行微米划入测试,研究了韧性材料在球形压头仪器化划入过程中的弹塑性变形行为.仪器化划入结果发现:随载荷的增加,金属的弹性回复率、残余划痕硬度、几何划痕硬度和侧向划痕硬度均趋于稳定.而高分子的弹性回复率,几何划痕硬度却是单调减小,很有可能产生损伤破坏,在最大载荷下利用线弹性断裂力学方法计算得到的断裂韧度与文献中的结果一致;在大载荷下,残余划痕硬度和侧向划痕硬度趋近于常数.残余划痕硬度大于几何划痕硬度;摩擦系数随着载荷的增大而非线性增大是由于球形压头几何形状的影响(灰口和球墨铸铁的摩擦系数平稳段是由于石墨的影响).大部分材料的划入响应与力学性能有密切关系:临界划痕应变(弹性回复率平稳阶段的起始应变)与屈服应变成正比;趋于稳定的残余划痕硬度与屈服强度有线性关系,并且与努氏硬度成比例.
Under progressive normal load,a spherical indenter(radius of 500μm)made of zirconia ceramic was used to explore the elastic-plastic deformation of ductile materials including three polymers and twenty metals during instrumented scratch tests.The results of instrumented scratch tests show that as the normal load increases,the elastic recovery ratio,residual scratch hardness,geometric scratch hardness,and lateral scratch hardness of metals can approach constant levels.However,the elastic recovery ratio and geometric scratch hardness of polymers decrease monotonically,possibly due to the occurrence of damage or failure.The fracture toughness values of polymers estimated at the largest normal load based on linear elastic fracture mechanics are consistent with the results in the literature.Under large loads,both residual scratch hardness and lateral scratch hardness of polymers can be approximated as being constant.Residual scratch hardness is found to be larger than geometric scratch hardness.The geometry of a spherical indenter helps explain the nonlinear increase in friction coefficient with increasing applied normal force(the constant levels of friction coefficients for gray and nodular cast irons are mainly caused by the influence of graphite).Most materials'scratch responses are closely related to their mechanical properties:the critical scratch strain(the initial strain of the steady state of elastic recovery ratio)is proportional to yield strain;there is a linear relationship between yield strength and the steady-state residual scratch hardness,which is proportional to Knoop hardness.
作者
刘明
徐智通
LIU Ming;XU ZhiTong(Fujian Provincial Key Laboratory of Terahertz Functional Devices and Intelligent Sensing,School of Mechanical Engineering and Automation,FuzhouUniversity,Fuzhou350108,China)
出处
《中国科学：物理学、力学、天文学》
CSCD
北大核心
2023年第4期54-70,共17页
Scientia Sinica Physica,Mechanica & Astronomica
基金
国家自然科学基金(编号:51705082)
福建省闽江学者特聘教授(编号:0020-510759)
福州大学旗山学者海外人才引进计划(编号:0020-650289)
晋江市福大科教园区发展中心科研项目(编号:2019-JJFDKY-11)资助。
关键词
仪器化划入
球形压头
渐进载荷
弹塑性变形
力学性能
instrumented scratch
spherical indenter
progressive load
elastic-plastic deformation
mechanical properties
