接触载荷对TC4钛合金微动磨损行为的影响

目的在不同的载荷和位移幅值下,结合微动图研究微动接触状态、滑移状态、损伤体积三者对微动摩擦磨损的影响以及不同微动接触状态和滑移状态下材料的损伤机理,为机械构件的微动磨损防护设计提供一定的理论支持。方法在相对湿度为50%、干摩擦条件下,运用SRV-V摩擦实验机,采用球/平面接触形式研究了TC4钛合金/GCr15钢球摩擦副的微动摩擦磨损行为。实验后,用原子力显微镜、纳米压痕仪、三维光学轮廓仪、场发射扫描电子显微镜及其自带的EDS,测试TC4试样的表面形貌及粗糙度、弹性模量与硬度、磨损体积与截面形貌和显微结构及磨斑、磨屑形貌成分等。结果在较低法向载荷下,完全滑移(GSR)占主导地位。磨粒磨损、粘着磨损、氧化磨损以及疲劳脱层是主要的损伤机理。另一方面,在较高法向载荷下,混合滑移(MSR)、部分滑移(PSR)占主导地位。损伤机制是由于高的应力集中,导致疲劳裂纹。此外,不同的微动运行条件下和材料损伤区域也不相同。完全滑移条件下,损伤主要集中在磨斑中心,而部分滑移条件下,损伤主要集中在磨斑边缘。结论切向摩擦力、微动振幅是影响微动磨损的重要因素。小位移幅值下,磨屑可以减缓接触面钛合金基体材料的微动磨损;而大位移幅值下,磨屑会加剧接触面基体材料的微动磨损。

Effect of Contact Load on Fretting Wear Behavior of TC4 Titanium Alloy

The work aims to study the effect of fretting contact states, sliding regimes and damaged volumes on fretting wear under different loads and displacement amplitudes with fretting maps and the damage mechanism of materials in different fretting contact and sliding states, so as to provide certain theoretical support for fretting wear protection of mechanical components. The fretting friction and wear behaviors of TC4 titanium alloy against GCr15 steel ball were studied by SRV-V friction tester with a ball/plane contact configuration in a condition of dry friction with 50% relative humidity. After the experiment, the surface morphology, roughness, modulus of elasticity, wear volume, cross sectional morphology, microstructure, wear scar, wear debris, etc. of TC4 samples were tested with atomic force microscope, nanoindentation instrument, three-dimensional optical surface profilometer, SEM with EDS. Under low normal load, fretting regime was a gross slip. Abrasive wear, adhesive wear, oxidation wear, and fatigue delamination were the main damage mechanisms. On the other hand, under large loads, fretting regime was a partial slip and a mixed slip. In this case, damage mechanisms were correlated with fatigue cracks due to highly concentrated stress. In addition, under different fretting conditions, material damage areas were also different. Under complete slip regime, the damage was mainly concentrated in the center of the wear scar, and under partial slip conditions, the damage was mainly concentrated on the edge of the wear scar. Tangential friction and fretting amplitude are important factors affecting fretting wear. Wear debris at small displacement amplitude can slow down fretting wear of titanium alloy matrix material at contact surface, while wear debris at large displacement amplitude can intensify fretting wear of matrix material at contact surface.