摩擦次表层结构演变对40Cr钢油润滑摩擦学行为的影响

Friction-Induced Subsurface Microstructural Evolution and Its Influence on the Lubricated Tribological Behavior of 40Cr Steel

为探究摩擦变形层组织结构演变及应变硬化特性与材料摩擦磨损行为间的联系,采用盘-销摩擦磨损试验机,在研究油润滑条件下40Cr钢/GCr15钢摩擦副摩擦学性能的基础上,采用扫描电子显微镜(SEM)、超景深三维金相显微镜(OM)和显微硬度计等对40Cr销试样磨损表面形貌及摩擦诱发的变形层组织结构和性能进行了分析。结果表明:随着磨损时间延长,试样的磨损机理由轻微粘着磨损发展为轻微粘着+局部轻度剥落的复合磨损;磨痕截面的塑性变形程度和硬化效应随磨损时间的延长逐渐上升,近表层局部区域形成湍流状结构并逐渐向表层迁移剥离,湍流状结构是循环摩擦接触过程中应变局域化和剪切失稳机制共同作用的结果,其发展和剥离过程与材料稳定磨损状态下的高磨损率密切相关。

For exploring the microstructural evolution of friction-induced deformation layer and the connection between strain-hardening characteristics and wear behavior,the lubricated tribological properties of 40Cr steel pin against GCr15 steel disc were investigated through disc-on-pin tribometer.Subsequently,the worn surface morphology,subsurface microstructures and properties of 40Cr pin were systematically analyzed using scanning electron microscopy(SEM),optical microscope(OM)and microhardness tester.Results showed that the wear mechanism of pin sample gradually changed from micro adhesion to micro adhesion+local spalling with increasing friction durations.Meanwhile,the microstructures beneath contact surface were subjected to severe plastic deformation and hardening effect.Pronounced vortex-like structures were generated in the localized subsurface zones due to high strain localization and shear instability.Moreover,with the prolongation of sliding duration,vortex-like structures suffered immigration and exfoliation from worn surface.The periodically forming and delaminating process of vortex-like structures was closely related to the high wear rate in stable wear stage.