Effect of deep cryogenic treatment on substructure of HS6-5-2 high speed steel

• Autorzy: Jeleńkowski J. , Ciski A. , Babul T.
• Języki publikacji: EN

Abstrakty

EN

Purpose: The purpose of this study was using of transmission electron microscopy (TEM) and differential scanning calorimetry (DSC) in order to reveal the changes in substructure of speed steel made with deep cryogenic treatment (DCT), in comparison with substructure formed by conventional heat treatment for secondary hardness. Design/methodology/approach: The HS6-5-2 high speed steel was heat treated in a conventional mode for secondary hardness or was processed in a mode with use of DCT, with and without next tempering. Transmission electron microscopy and scanning electron microscopy observations were carried out. Studies of thermal stability in range of temperatures from -196 °C to 400 °C were performed using differential scanning calorimetry (DSC). Findings: Observations made with aid of SEM-TEM microscope revealed the presence of high density of globular clusters situated at dislocations, and precipitations of the fine carbide plates, located in twinned crystals of martensite. Thermal analysis (DSC) showed an occurrence of higher exothermic effects in specimens treated with use of DCT, than in specimens heat treated conventionally. In steel samples after quenching and DCT the additional exothermic effect was observed. Electron diffraction in TEM studies of these specimens allowed to observe reflections of which indexing exhibited that the precipitated carbide phase has crystallographic structure of B1 type. Research limitations/implications: Extremely high dispersion of carbide phases and a high state of stress that accompanies the stage of precipitation, make difficult the identification of the lattice structure of precipitations, its crystallographic relationships and the degree of coherence with the matrix. Identification of the type of carbides (ĺ, ç, B1, and others) and their coherence with matrix become time-consuming. This important issue requires detailed studies using high-resolution microscopes. Conditions of the early stage of the precipitation process affect the stability of induced strengthening and service-life of tools. Practical implications: Research of HS6-5-2 high speed steel allowed concluding that DCT, besides refinement of martensite grain size, causes an increase of quantity of sites for nucleation of clusters, in which during tempering the B1 carbides are formed. These fine, coherent with matrix and stable carbides are found to be responsible for enhancement of toughness and wear resistance of HSS tools. Originality/value: The issue of DCT is a niche topic in Poland, there are no detailed studies on the changes taking place during this process.

Słowa kluczowe

EN

tool material; high-speed steel; carbide; cryogenic machining

PL

materiał narzędziowy; stal szybkotnąca; węglik; obróbka kriogeniczna

• Wydawca: International OCSCO World Press
• Czasopismo: Journal of Achievements in Materials and Manufacturing Engineering
• Rocznik: 2010
• Tom: Vol. 43, nr 1
• Strony: 80--87
• Opis fizyczny: Bibliogr. 10 poz., rys., tabl.

Twórcy

autor

Jeleńkowski J.

autor

Ciski A.

autor

Babul T.

• Institute of Precision Mechanics, ul. Duchnicka 3, 01-796 Warsaw, Poland,

Bibliografia

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