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Effect of high-temperature heating on chemical changes in M7C3 carbides of AISI D2 tool steel

Nykiel T., Hryniewicz T.

International Letters of Chemistry, Physics and Astronomy

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2014

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Vol. 17, iss. 3

258--271

EN

The paper presents the study results obtained on 16H12MF/NC11LV/D2 tool steel. The main purpose of the study was to establish the chemical composition of the coarse primary M7C3 carbides occurring in that steel after a standard soft annealing. The effect of high-temperature annealing in the air atmosphere was investigated. The study was limited to the decarburized layer, on the distance of about 0.4 mm from the surface, of hardened steel after annealing and austenitizing at 1150 ºC in the air atmosphere for the periods of 30 and 90 minutes. It was found that the coarse primary M7C3 carbides of the annealed D2 tool steel differ significantly as to the contents of Cr, Mo, and V, and in the most degree to the contents of chromium and molybdenum. The average concentration of chromium rises successively with the growth of austenitizing time. On the other hand, the concentrations of molybdenum and vanadium are lower after 30 minutes of austenitizing than their concentrations in the similar carbides of the annealed steel. Prolongation of the austenitizing time up to 90 minutes results in the increase of molybdenum and vanadium contents in the coarse carbides. It was found that austenitizing of AISI D2 tool steel at the temperature of 1150 ºC in the air atmosphere leads to precipitation of the second phase, brighter in the BSE_Z pictures, in relation to the matrix of carbides, with the amount and magnitude being higher with the annealing time.

2

Fluctuations in Chemical Composition of M7C3 Carbides in the Soft Annealed Nc11lv/D2 Steel

Hryniewicz T., Nykiel T.

Advances in Materials Science

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2014

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Vol. 14, nr 1(39)

24--30

EN

The paper presents the study results on chemical composition of the coarse primary M7C3 carbides occurring in the soft annealed NC11LV/D2 tool steel consisting of: 1.53% C; 11.65% Cr; 0.01% W; 0.81% Mo; 0.068% V; (balance iron plus admixtures), used for cold operation. The microanalyzer of type SEMPROBE Su-30, French made by CAMECA Co., equipped with two WDS X-ray spectrometers and an EDS VOYAGER 3 100, NORAN Instruments Co., made in USA. It was found that out of the three alloying elements occurring in the big carbides of the annealed NC11LV/D2 steel, i.e. Cr, Mo, and V, the chromium appears to be the most uniformly distributed. The big carbides vary concerning C, Cr, Mo, V; the greatest differentiation degree of the contents of Mo and Cr, and the least - of vanadium. The average chemical composition of the big/coarse carbides is as follows: C = 9.42±1.28%; Cr = 44.17±2.95%; Mo = 4.48±3.52%; V = 4.53±0.31%; balance Fe.

3

On the M7C3 carbides coagulation and coalescence during high-temperature austenitizing of 2% C and 12% Cr type steel

Nykiel T., Hryniewicz T.

Advances in Materials Science

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2003

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Vol. 3, nr 2(4)

61--70

EN

The paper presents the results of investigation of carbide grain joints formation during high-temperature austenitizing of steel of about 2% C and 12% Cr type with the additives of tungsten and vanadium. Parameters of distributions of the number of carbide grain joints as the function of austenitizing time at 1150°C are determined. It was found that in case of carbide grain joints with distinctly outlined boundary division the angles of carbides misorientation forming joints are greater than the angles in joints of the boundary which course is difficult to establish.

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Effect of austenitizing parameters on dissolution of carbides in gamma solution and chemical composition of matrix in the hardened steel of 2% C and 12% Cr type with additives of W, Mo, V

Nykiel T., Hryniewicz T.

Advances in Materials Science

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2003

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Vol. 3, nr 2(4)

49--60

EN

The NCWV/D3 tool steel was the subject of the study. In the course of the investigation carried out it was found that during austenitizing of the steel the carbides contents decreased from 24.84 wt% in the annealed state down to 13.33 wt% after austenitiz-ing at 1150 °C during 30 minutes. It was also stated that the carbides contents in the quenched steel after austenitizing in the temperature range from 900 to 1150 °C during 30 minutes may be determined from the relationship cb[wt%] = 28.60 - 0,46e 0.003T Dissolution of carbides during austenitizing brings about the increase of elements Cr, W, and V contents in austenite up to 7.27%, 1.06%, and 0.086%, respectively, after austenitizing at 1150 °C during 30 minutes. It was also noticed that there is a rectilinear correlation between the contents of dissolved carbides in austenite and the contents of Cr and W in matrix of the tool steel quenched after austenitizing in the temperature range from 900 to 1150 °C and constant time of 30 minutes.

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Effect of austenitizing parameters and sub-zero treatment on kinetics of retained austenite transformation in NCWV/D3 tool steel.

Hryniewicz T., Nykiel T.

Inżynieria Materiałowa

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2000

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R. XXI, nr 1

32-36

EN

The paper is devoted to the kinetics of transformation of the retained austenite in NCWV/D3 steel. The work has been devided into two parts. The first part of the work concerns the study method and it reveals the tool steel structure. A special attention is paid to the retained austenite. The purpose of the research, is to reveal the effect of the quenching conditions and sub-zero treatment (at -196 degrees centigrade) of steel containing 1.95%C, 11.56%Cr, 1.32%W, and 0.31%V on the relative content of retained austenite, chemical composition of matrix, stability of the retained austenite and the steel hardness. The work is intended to contribute to the research connected with the behaviour of retained austenite during deposition of TiN and Ti(CN) coatings.

PL

Niniejszy artykuł poświęcony jest kinetyce przemiany austenitu szczątkowego w stali narzędziowej NCWV, odpowiadającej stali D3 wg norm amerykańskich. Całość pracy podzielono na dwie części. W pierwszej części prezentowanej w niniejszym artykule, podano metodykę badań oraz strukturę badanej stali narzędziowej, ze szczególnym uwzględnieniem roli i przemiany austenitu szczątkowego. Celem badań jest ukazanie wpływu warunków hartowania i obróbki podzerowej, przy temperaturze -196 stopni Celsjusza, stali zawierającej 1,95%C, 11,56%Cr, 1,32%W i 0,31%V, na względną zawartość austenitu szczątkowego, skład chemiczny osnowy, stabilność austenitu szczątkowego oraz twardość stali po obróbce cieplnej. Praca niniejsza jest częścią badań związanych z zachowaniem się austenitu szczątkowego.