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  • Effect of deep cryogenic treatment on steel wear and corrosion resistance [Elektronski vir]
    Podgornik, Bojan, 1970- ...
    In the last decade deep cryogenic treatment (DCT) is getting increased attention in many tool applications. It is defined as an add-on process to conventional heat treatment and involves cooling the ... material to about %196 °C. Numerous investigations concerning cold-work and high-speed steels have shown that this kind of treatment can lead to improved material performance, including hardness, toughness and wear resistance. The main reason for this is contributed to the complete elimination of retained austenite and enhanced precipitation of very small carbides dispersed in the tempered martensitic structure. However, there are some contradictory results, with investigations reporting improved as well as deteriorated properties after deep cryogenic treatment, especially when it comes to wear resistance. Another property not being given enough attention is corrosion resistance of tool steels and how it is affected by DCT. The aim of this research work was to investigate the effect of deep cryogenic treatment on corrosion and wear resistance of tool steels and to determine how these properties are related to steel composition and mechanical properties obtained (hardness, fracture toughness). Investigation was performed on two coldwork tool steels and one high-speed steel all produced by powder metallurgy. For each steel three combinations of austenitizing and tempering temperatures were used resulting in high hardness/low toughness, medium hardness/medium toughness and low hardness/high toughness combinations. The same heat treatment conditions were combined also with deep cryogenic treatment in order to evaluate its effect on the tool steel properties. Properties investigated included hardness, fracture toughness, dry sliding wear resistance, impact wear resistance and corrosion resistance. Corrosion resistance testing included determination of corrosions potential, linear polarization resistance, electrochemical impedance spectroscopy and potentiodynamic polarization scan. Results show that the type and chemical composition of the tool steel considerably affect the way how deep cryogenic treatment changes mechanical, tribological and corrosions resistance of the tool steel. For lower carbon and higher W and Co containing cold-work tool steel toughness can be considerably improved but is accompanied with hardness and wear resistance drop. In the case of high carbon cold work tool steel negative effect of DCT is further intensified. However, although DCT had only minor effect on properties of high-speed steel, it led to improved hardness, fracture toughness as well as wear and corrosions resistance.
    Vir: Heat treatment and surface engineering for automotive [Elektronski vir] : proceedings
    Vrsta gradiva - prispevek na konferenci
    Leto - 2019
    Jezik - angleški
    COBISS.SI-ID - 1544874

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