Wyniki wyszukiwania - Biblioteka Nauki

1

Analysis of the kinetics of precipitation of MX-type interstitial phases in microalloyed steels

100%

Opiela M.

Journal of Achievements in Materials and Manufacturing Engineering

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2011

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tom Vol. 47, nr 1

7--18

EN

Purpose: The paper presents analysis of the kinetics of precipitation of MX-type (M - metal, X - metalloid) interstitial phases in austenite of constructional steels microalloyed with Nb, Ti, V and B, assigned for production of forged machine elements with the use of thermo-mechanical treatment. Design/methodology/approach: The analysis was conducted basing on the dependence of solubility of MX-type phases in austenite as a function of temperature. The research of influence of austenitizing temperature in a temperature range from 900 to 1200°C on grain size of primary austenite has been used to verify the analysis. Findings: The kinetics of TiN, TiC and NbC precipitation as well as the temperature sequence of precipitation of these phases have been determined. The investigation of influence of austenitizing temperature on the grain size of primary austenite confirmed correctness of the analysis. Research limitations/implications: The analysis was done basing on the thermodynamic model proposed by Adrian, assuming that only individual, single MX phases are soluble in austenite. Practical implications: The studies provide the basis for proper design of manufacturing process of thermomechanical treatment of high strength forged machine parts obtained from microalloyed steels. Originality/value: The kinetics of precipitation of interstitial phases in newly elaborated microalloyed steels has been compiled.

2

Wpływ ziaren austenitu pierwotnego na mikrostrukturę i właściwości mechaniczne modyfikowanego żeliwa z grafitem płatkowym

86%

Kopyciński D. , Guzik E. , Szczęsny A. , Dorula J.

Przegląd Odlewnictwa

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2014

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tom Vol. 64, nr 11-12

456--462

PL

Prowadzone badania wykazują, że wprowadzenie sproszkowanego żelaza do wytapianego żeliwa o niskiej zawartości siarki przed zabiegiem modyfikacji prowadzonej konwencjonalnym modyfikatorem grafityzującym pozwala na uzyskanie właściwości mechanicznych zbliżonych do wartości uzyskiwanych w trakcie modyfikacji żeliwa o podwyższonej zawartości siarki. Prowadzony zabieg powoduje wzrost liczby zarodków krystalizacji dendrytów austenitu pierwotnego. W tym przypadku, cząsteczki sproszkowanego żelaza działają, jako substraty dla zarodkowania austenitu pierwotnego, podobnie do zachowania się sieci regularnej siatki krystalograficznej. Zwiększona liczba dendrytów austenitu pierwotnego powoduje zmniejszenie się przestrzeni międzydendrytycznych utrudniając tym samym tworzenie się ziaren eutektycznych, czego efektem jest wzrost właściwości mechanicznych.

EN

The study proves that by introducing the iron powder to low-sulphur cast iron still before the inoculation carried out with a conventional graphitising inoculant, the mechanical properties similar to those obtained during the inoculation treatment carried out on cast iron with the recommended high sulphur content are achieved. The said operation increases the number of crystallisation nuclei of the primary austenite dendrites. In this case, the iron particles act as substrates for the nucleation of primary austenite due to a similar crystallographic behaviour of the regular face cantered cubic lattice. The more numerous are the dendrites of primary austenite, the less free space is available in the interdendritic spaces for the formation of graphite eutectic grains, which makes the mechanical properties higher.

3

Effect of alloying elements on branching of primary austenite dendrites in Ni-Mn-Cu cast iron

72%

Janus A.

Archives of Foundry Engineering

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2011

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tom Vol. 11, iss. 2

51-54

EN

Within the research, determined were direction and intensity of influence of individual alloying elements on branching degree of primary austenite dendrites in austenitic cast iron Ni-Mn-Cu. 30 cast shafts dia. 20 mm were analysed. Chemical composition of the alloy was as follows: 2.0 to 3.3 % C, 1.4 to 3.1 % Si, 2.8 to 9.5 % Ni, 0.4 to 7.7 % Mn, 0 to 4.6 % Cu, 0.14 to 0.16 % P and 0.03 to 0.04 % S. Analysis was performed separately for the dendrites solidifying in directional and volumetric way. The average distance "x" between the 2nd order arms was accepted as the criterion of branching degree. It was found that influence of C, Si, Ni, Mn and Cu on the parameter "x" is statistically significant. Intensity of carbon influence is decidedly higher than that of other elements, and the influence is more intensive in the directionally solidifying dendrites. However, in the case of the alloyed cast iron Ni-Mn-Cu, combined influence of the alloying elements on solidification course of primary austenite can be significant.

4

Rozwój struktury stali typu TRIP podczas obróbkiplastycznej na gorąco

72%

Grojcar A. , Opiela M.

Hutnik, Wiadomości Hutnicze

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2008

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tom Vol. 75, nr 8

402-404

PL

W pracy zbadano zachowanie się nowo opracowanej stali C-Mn-Si-Al z mikrododatkami Nb i Ti w warunkach obróbki plastycznej na gorąco. Wyznaczono krzywe a-e oraz ujawniono strukturę austenitu pierwotnego próbek odkształconych do zadanego odkształcenia plastycznego oraz wytrzymanych izotermicznie po odkształceniu przez 10 s. Na tej podstawie wyznaczono warunki kilkuetapowego ściskania symulującego końcowe przepusty walcowania.

EN

Behaviour of new-developed C-Mn-Si-Al steel with Nb and Ti microadditions in hot-working conditions was investigated in the work The o-e curves were determined and primary austenite structures of the specimens deformed to a given strain and isothermally held for 10 s after deformation were revealed. On this basis, the conditions of multistage compression simulating final rolling passes were determined.

5

Effect of alloying elements on solidification of primary austenite in Ni-Mn-Cu cast iron

72%

Janus A. , Kurzawa A.

Archives of Foundry Engineering

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2011

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tom Vol. 11, iss. 2 spec.

93--96

EN

Within the research, determined were direction and intensity of alloying elements influence on solidification way (directional or volumetric) of primary austenite dendrites in hypoeutectic austenitic cast iron Ni-Mn-Cu. 50 cast shafts dia. 20 mm were analysed. Chemical composition of the alloy was as follows: 1.7 to 3.3 % C, 1.4 to 3.1 % Si, 2.8 to 9.9 % Ni, 0.4 to 7.7 % Mn, 0 to 4.6 % Cu, 0.14 to 0.16 % P and 0.03 to 0.04 % S. The discriminant analysis revealed that carbon influences solidification of primary austenite dendrites most intensively. It clearly increases the tendency to volumetric solidification. Influence of the other elements is much weaker. This means that the solidification way of primary austenite dendrites in hypoeutectic austenitic cast iron Ni-Mn-Cu does not differ from that in an unalloyed cast iron.

6

Opracowanie warunków kucia na podstawie analizy kinetyki wydzielania się w austenicie faz międzywęzłowych typu MX

72%

Opiela M.

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tom Vol. 78, nr 8

646--649

PL

W pracy przeprowadzono analizę kinetyki wydzielania się w austenicie faz międzywęzłowych typu MX w nowo opracowanej stali mikrostopowej przeznaczonej do wytwarzania kutych elementów maszyn metodą obróbki cieplno-plastycznej. Weryfikację przeprowadzonej analizy stanowiły badania wpływu temperatury austenityzowania w zakresie od 900 do 1200 oC na wielkość ziaren austenitu pierwotnego. Na podstawie przeprowadzonej analizy opracowano temperaturowe warunki kucia badanej stali.

EN

In this work, the analysis of releasing kinetics of MX-type interstitial phases in the austenite in newly worked out microalloy steel, was made. The investigated steel is assigned for production of forged parts of machines by thermo-mechanical treatment. As a verification of the analysis, the effect of austenitizing temperature, at the range of 900÷1200 °C, on the grain size of primary austenite was investigated. The temperature conditions of forging process of investigated steel were determined on the basis of the carried out analysis.