LIU Gang,LIU Jing,DAI Yan,YANG Feng,CHEN Li.Surface Composite Strengthening and Wear Behavior of TA1 Titanium Alloy[J],52(10):171-180
Surface Composite Strengthening and Wear Behavior of TA1 Titanium Alloy
Received:September 30, 2022  Revised:April 12, 2023
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DOI:10.16490/j.cnki.issn.1001-3660.2023.10.013
KeyWord:TA1 titanium alloy  mechanical deformation  WC particle strengthening  composite strengthening coating  friction and wear
              
AuthorInstitution
LIU Gang School of Materials and Architectural Engineering, Guizhou Normal University, Guiyang , China
LIU Jing School of Materials and Architectural Engineering, Guizhou Normal University, Guiyang , China
DAI Yan School of Materials and Architectural Engineering, Guizhou Normal University, Guiyang , China
YANG Feng School of Materials and Architectural Engineering, Guizhou Normal University, Guiyang , China
CHEN Li School of Materials and Architectural Engineering, Guizhou Normal University, Guiyang , China
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Abstract:
      Surface mechanical composite strengthening is a one-step surface modification technology with simple process, low energy consumption and flexible coating material selection. It can improve the surface properties of TA1 titanium alloy, such as hardness and wear resistance. Through high-speed movement of the grinding ball on the surface of the TA1 specimen, the impact and friction was repeated, which caused plastic deformation and gradual work hardening of the surface layer of the TA1 titanium alloy substrate. With the action of grinding ball, the surface grain size of dislocation was further mechanically induced by product and even tangles, which gradually lead to the formation of sub-grain boundaries and even amorphization, and thus lead to elaboration and strengthening, and the formation of a reinforcement layer of certain thickness. In addition, a small amount of added WC powder made the powder be repeatedly extruded and deformed at high speed impact of the grinding ball, and produced cold welding and mechanical coating on the surface of TA1 titanium alloy, thus forming the coating and further strengthening the effect. The material used in this experiment was TA1 titanium alloy, and the sample was Φ15 mm×8 mm columnar material. A planetary mechanical ball milling device, zirconia ball milling tank and stainless steel ball were used to strengthen the TA1 titanium alloy surface by mechanical deformation and solid-phase coating at 0.05 MPa nitrogen atmosphere and 350 r/min speed for 8 h with WC powder as the reinforcing medium. Testing methods, such as Vickers hardness tester, optical 3D profilometer, XRD, SEM-EDS, and reciprocating wear machine were used to test and characterize the structure and wear resistance of the composite reinforced layer. The surface roughness of TA1 increased obviously. After mechanical strengthening, the composite strengthening layer of TA1 titanium alloy was composed of WC coating+deformed fine grain region. The thickness of the hardened layer was about 20-40 μm, and the structure was compact and uniform. The thickness of the deformation fine grain zone was about 30 μm, which was composed of relatively small equiaxed grain. The nano structure layer also had some twins and dislocations. The hardness of the coating zone reached 1 000HV0.25, and the outer layer of the reinforced layer was mainly formed by the adhesion of uniform hard WC particles, which significantly improved the hardness of TA1 titanium alloy. XRD analysis showed that the maximum distribution depth of WC coating in the strengthened layer exceeded 40 μm. The main surface component of the composite reinforced layer was WC. The WC particle-reinforced coating had a strong anti-friction effect. TA1 titanium alloy had a stable low friction coefficient in the wear process after strengthening, and the low friction coefficient was stable around 0.2, and the interval of low friction coefficient lasted for a long time. The presence of high hardness and thick WC particles reinforced coating strengthens the coating resistance to deformation during the wear process, and uneven WC coating in the process of wear contact area is lesser. At the same time, it gradually produces small grits, gives play to the role of the lubrication, keeps the friction coefficient in a low range, and improves the wear resistance. When the WC coating on the surface of TA1 sample is gradually worn away, and the soft TA1 matrix is exposed, its anti-plastic deformation ability is greatly weakened, and its wear mechanism is mainly abrasive wear and oxidation wear.
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