Elastic-Plastic Properties of Tribological Layers of WC–(Fe–Mn–C) Composites Formed after High-Speed Sliding Against a Steel

• Published in: Steel in translation 2022, Vol.52 (8), p.742-748
• Main Authors: Savchenko, N. L., Sevost’yanova, I. N., Tarasov, S. Yu
• Format: Article
• Language: English
• Subjects: Antifriction; Chemistry and Materials Science; Composite materials; Contact pressure; Elastic properties; Elastoplasticity; Fracture toughness; High speed tool steels; Manganese; Materials Science; Modulus of elasticity; Nanohardness; Nanoindentation; Plastic properties; Sliding; Thickness; Tribology
• ISSN: 0967-0912; 1935-0988
• DOI: 10.3103/S0967091222080125

Elastoplastic properties of tribological layers generated on WC–(Fe–Mn–C) composites with matrices composed of γ-iron containing 20 wt % Mn (WC–80G20) and of γ + α' with 4 wt % Mn (WC–80G4) after sliding against a high-speed steel disk at contact pressure of 5 MPa and sliding speeds in the range from 10 to 37 m/s have been investigated. It was established that the main factor determining the morphology of the worn surface is the sliding speed. At sliding speeds of 10 and 20 m/s, fine-grained mechanically mixed tribolayers of 3–4 µm in thickness formed. As the sliding speed increased to 30–37 m/s, the thickness of the tribolayers reached 10–15 µm, and the structure consisted of oxidized fragments of WC–(Fe–Mn–C) composites and FeWO 4 complex oxide without any sharp boundary observed. Both highest values of nanohardness (~33 GPa) and effective Young’s modulus (~523 GPa) were achieved on the WC–80G4 tribolayer after friction at 10 m/s when the nanoindentor indented agglomerates of fragmented WC grains. This contrasted with the properties of the tribolayers formed at sliding velocities above 20 m/s. The results of nanoindentation showed an obvious effect of tribochemically induced softening in the generated tribolayer after high-speed sliding at 37 m/s. Such a layer had a composite microstructure consisting of fragmented composite components cemented in-situ by tribochemically formed FeWO 4 and, in addition to antifriction properties, had an increased indentation fracture resistance.