Abstract
For surface hardening of a large range of engineering parts, surfacing is used with materials based on iron-chromium steel, which provide metal coatings with high strength and corrosion resistance. Based on them, flux-cored surfacing wires containing 13-17% chromium have been developed. At that, insufficient attention is paid to studies of the wear resistance of metal deposited by such wires. The structural features, wear resistance, and characteristics of the friction surface of the metal deposited by flux-cored wire ПП 12 Х 15 were investigated. Metallographic and durometric studies have shown that such a metal has a ferritic-martensitic structure with a hardness of 408-429 HV, as well as the presence of 5-ferrite and carbides in it, whose hardness is 358-376 HV and 551-609 HV. It was found that the mass wear of such a metal was 0.00753 g/m, the linear wear was 0.0235 mm/m, and the friction coefficient was 0.464. After friction loading, the topography of the surface was characterized by a grooved surface with deep tears, the relief of the wear surface with the presence of both small and large particles of wear products. The ПП 12 Х 15 coating with its relatively low hardness does not have sufficient resistance to the introduction of counter-microroughness vertices, which contributes to high wear rate and an increased friction coefficient due to the increased number of microcritical foci. For the microstructure of the surface layers after wear, a high degree of fragmentation of the investigated material was noted due to the formation of slip bands, characterized by a regular arrangement of dipole dislocation clusters. Friction loading turns these bands into foci of localized deformation in the form of mesa bands and leads to selective ejection of fracture products from the contact zone. The wear mechanism of metal deposited by a flux-cored wire ПП 12 Х 15 was due to the presence of chromium carbides, which act as obstacles for the sliding of dislocations under conditions of plastic deformation of the surface during friction.
Highlights
It was found that the mass wear of such a metal was 0.00753 g/m, the linear wear was 0.0235 mm/m, and the friction coefficient was 0.464
The topography of the surface was characterized by a grooved surface with deep tears, the relief of the wear surface with the presence of both small and large particles of wear products
The ПП12Х15 coating with its relatively low hardness does not have sufficient resistance to the introduction of counter-microroughness vertices, which contributes to high wear rate and an increased friction coefficient due to the increased number of microcritical foci
Summary
The wear mechanism of metal deposited by a flux-cored wire ПП12Х15 was due to the presence of chromium carbides, which act as obstacles for the sliding of dislocations under conditions of plastic deformation of the surface during friction. Исходя из вышеизложенного в работе изучались структурные превращения при изнашивании, фрикционное упрочнение и основные трибологические свойства металла, наплавленного хромистой порошковой проволокой. Твердость наплавленного металла измеряли по методу Роквелла на приборе ТК-2, а микротвердость структурных составляющих определяли по методу Виккерса на микротвердомере Shimadzu HMV-2 при нагрузках 10 и 50 г. Установлено, что значения твердости металла, наплавленного порошковой проволокой ПП12Х15, находятся в пределах 35–38 HRC, химический состав которого приведен в табл.
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