Abstract
The machined surface quality, especially the micro-hardness of machined surface layers, is strongly correlated to the friction and wear characteristics of titanium alloy engineering parts. Therefore, to explore relationship of the local surface micro-hardness change in multistep machining and the surface wear resistance of the machined parts is urgently necessary. The machined surfaces were acquired through two-step (roughing and finishing) and three step (roughing, semi-finishing, and finishing) cylindrical turning experiments. The dry friction and wear tests were carried out by UMT-2 friction and wear tester on the multistep final machined surface along the feed direction. The surface wear microtopography and subsurface microstructure were observed and analyzed by scanning electron microscope. The micro-hardness variation in the local area of the finishing surface will cause the extension of unstable friction time stage while withstanding the cyclic and alternating contact stresses, and the soft–hard alternating area should be the sources of friction and wear defects, for instance cracks, peeling pits, fracture striations and even the wear fracture zone to crack propagation and peeling off. This will be of great significance to accurately control the machined surface quality and adaptively improve the surface wear resistance of titanium alloy components.
Highlights
Titanium alloys are widely used in aerospace and navigation due to their high strength, low density and good corrosion resistance
The micro-hardness variation in the local area of the finishing surface will cause the extension of unstable friction time stage while withstanding the cyclic and alternating contact stresses, and the soft–hard alternating area should be the sources of friction and wear defects, for instance cracks, peeling pits, fracture striations and even the wear fracture zone to crack propagation and peeling off
This paper aimed to study the effect of surface micro-hardness change in multistep machining on the friction and wear characteristics along the feed direction
Summary
Titanium alloys are widely used in aerospace and navigation due to their high strength, low density and good corrosion resistance. Due to the poor wear resistance of titanium alloys [1,2], their performance is seriously affected, which limits their application in this field. It is important to study and understand the influence of surface integrity on the friction and wear properties of titanium alloys, and to improve its performance and life. Regarding the study of friction and wear properties, many scholars at home and abroad have devoted effort to the study of surface pretreatment (microelement coating, heat treatment of materials) or different experimental conditions. Cong et al [4] found that the wear resistance of alloy samples (Low-carbon steel) at room temperature and 450 ◦ C could be improved to some extent by performing double-glow plasma surface alloying treatment. The wear scar of the titanium alloy matrix was furrow morphology, and the wear mechanism was stripping wear and adhesive wear; the wear mechanism of the
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