Effect of vacuum deposited coatings on the fatigue strength of commercial-grade titanium

Autor: A. V. Rutkovskii, B. A. Lyashenko, A. G. Trapezon
Rok vydání: 1995
Předmět:
Zdroj: Strength of Materials. 27:659-664
ISSN: 1573-9325
0039-2316
DOI: 10.1007/bf02206239
Popis: A procedure is described and results are given for a study of the effect of coatings made of nitrides TiN and (CrTi)N on the fatigue strength σ−1 of sheet titanium VT1-0 with high-frequency (∼ 10 kHz) cyclic bending. Use of cantilever specimens of simple geometry consisting of two steps of constant cross section made it possible on one hand to improve their technological efficiency, and on the other hand to provide the maximum reliability for experimental results in view of accurate determination of the failure stresses by calculation. Due to high-frequency loading the test time is reduced including the time for the production and preparation of specimens due to shortening them with an increase in working frequency during resonance tests. Six batches of material are tested including uncoated specimens. It is shown that with a base thickness of 0.5 mm coatings on TiN and (CrTi)N with a thickness of 0.6 Μm increase σ−1 by 11.3 and 7.5% respectively. Introduction beneath the TiN coating of intermediate layers of Ti and Cr with a thickness up to 0.25 Μm leads to a reduction in σ−1 compared with this characteristic for a TiN coating without an interlayer. An interlayer of Cr promotes a reduction in σ−1 to a level below that for uncoated material by −3.8%, but a layer Ti increases it above this level by +3.8%. Analysis of the results obtained shows that introduction of the ‘worst’ Cr interlayer with a thickness of 0.5 Μm beneath the worst of the two comparable coatings, i.e., a (CrTi)N coating, increases the value of σ−1 by 17% compared with σ−1 for uncoated material. A practical possibility is noted for optimizing coatings and improving σ−1 as a result varying production process parameters without reorganizing it. This makes it possible to solve the problem with the minimum expenditure of time and materials.
Databáze: OpenAIRE
Externí odkaz: