Wyniki wyszukiwania - BazTech

1

The Effects of Laser Surface Hardening on Microstructural Characteristics and Wear Resistance of AISI H11 Hot Work Tool Steel

Šebek M., Falat L., Kováč F., Petryshynets I., Horňak P., Girman V.

Archives of Metallurgy and Materials

|

2017

|

Vol. 62, iss. 3

1721--1726

EN

The present study deals with the effects of laser surface treatment on microstructure evolution and wear resistance of AISI H11 hot work tool steel in quenched and tempered condition. The most upper laser-affected zone is characterized by re-melted microstructure consisting of dendrite cells with fresh non-tempered martensite, retained austenite and inter-dendritic carbidic network. The subsolidus microstructure just beneath the re-melted zone represents the most laser surface hardened zone consisting of fresh non-tempered martensite with fine and coarse carbides as a result of overheating the original QT substrate microstructure. The highest microhardness values in the range from 775 to 857 HV were measured for the LSH microstructure and the most softened microstructure exhibited the minimum hardness of 530 HV. The laser treated samples showed the improvement of their surface wear resistance by 35%.

2

Microstructure and Texture Evolution in Temper Rolled Fe-Si Steels with New System Nano-Inhibitors under the Dynamic Annealing Conditions

Kováč F., Petryshynets I., Horňak P.

Archives of Metallurgy and Materials

|

2017

|

Vol. 62, iss. 3

1727--1732

EN

This work investigates the microstructure and texture evolution in grain-oriented electrotechnical steel with a new inhibition system based on vanadium carbides nano-particles. The novel approach for the preparation of this steel with appropriate final magnetic properties combines not only nanoinhibitors based on the vanadium carbides precipitations but also includes straininduced grain growth mechanism in combination with dynamic continuous annealing during the secondary recrystallization. The experimental grain-oriented steel with proposed new chemical composition was prepared in laboratory conditions. The texture analysis has shown that suggested procedure led the formation of sufficiently strong {110}<001> Goss texture during the short time period of a final annealing process, which is comparable to that obtained in the conventionally treated grain-oriented steels.

3

Pressurized Recuperator for Heat Recovery in Industrial High Temperature Processes

Gil S., Góral J., Horňak P., Ochman J., Wiśniewski T.

Archives of Metallurgy and Materials

|

2015

|

Vol. 60, iss. 3A

1847--1850

EN

Recuperators and regenerators are important devices for heat recovery systems in technological lines of industrial processes and should have high air preheating temperature, low flow resistance and a long service life. The use of heat recovery systems is particularly important in high-temperature industrial processes (especially in metallurgy) where large amounts of thermal energy are lost to the environment. The article presents the process design for a high efficiency recuperator intended to work at high operating parameters: air pressure up to 1.2 MPa and temperature of heating up to 900°C. The results of thermal and gas-dynamic calculations were based on an algorithm developed for determination of the recuperation process parameters. The proposed technical solution of the recuperator and determined recuperation parameters ensure its operation under maximum temperature conditions.

PL

Rekuperatory i regeneratory są ważnymi urządzeniami systemów odzysku ciepła w ciągach technologicznych procesów przemysłowych i powinny charakteryzować się wysoką temperaturą podgrzewania powietrza, niewielkimi oporami przepływu, a także długim czasem eksploatacji. Stosowanie układów do odzysku ciepła ma szczególne znaczenie w wysokotemperaturowych procesach przemysłowych (zwłaszcza w hutnictwie), gdzie tracone są do otoczenia duże ilości energii cieplej. W artykule zaprezentowano projekt procesowy wysokosprawnego rekuperatora przeznaczonego do działania przy wysokich parametrach roboczych: ciśnienia powietrza do 1.2 MPa i temperatury podgrzania do 900°C. Wyniki obliczeń cieplnych i gazodynamicznych uzyskano w oparciu o opracowany algorytm do wyznaczania parametrów procesowych rekuperacji. Zaproponowane rozwiązanie techniczne rekuperatora i wyznaczone parametry rekuperacji umożliwiają jego działanie w maksymalnych warunkach termicznych.

4

Microstructure Evolution and Mechanical Properties of C-Mn Cold Rolled Dual Phase Steel after Continuous Annealing Process in Laboratory Conditions

Šebek M., Horňak P., Zimovčák P., Longauer S.

Archives of Metallurgy and Materials

|

2014

|

Vol. 59, iss. 2

821--824

EN

The article deals with the influence of annealing parameters on evolution of microstructure and mechanical properties of dual phase steel. Dual phase steel was annealed in laboratory conditions according to the three chosen cycles of annealing: into intercritical region (780°C), into austenite region (920°C) and into austenite region (920°C) by subsequently cooling into intercritical region (780°C) with the hold at the temperature of 495°C. Simulation of annealing regimes by thermo-mechanical simulator Gleeble was done. The obtained microstructure consists from three phases: ferritic matrix, martensite and martensite/ bainite grains. For the microstructure identification the TEM and nanoindentation experiments were performed.

PL

Praca dotyczy wpływu parametrów wyżarzania na zmiany mikrostruktury i właściwości mechaniczne stali dwufazowej C-Mn. Stal dwufazową poddano wyżarzaniu w warunkach laboratoryjnych według trzech wybranych cykli: w zakresie między krytycznym (780°C). w obszarze austenitu (920°C) i w obszarze austenitu (920°C) ze schładzaniem do zakresu międzykrytycznego (780°C) przy temperaturze wytrzymania 495°C. Przeprowadzono symulację schematów wyżarzania przy użyciu symulatora obróbki cieplno-plastycznej Gleeble. Uzyskana mikrostruktura składa się z trzech faz: osnowy terrytycznej. martenzytu oraz ziaren martenzytu/bainitu. W celu identyfikacji mikrostruktury wykonano badania metodą TEM oraz nanoindentacji.

5

Investigation of retained austenite stability in Mn-Si TRIP steel in tensile deformation condition

Muránsky O., Horňak P., Lukáš P., Zrník J., Šittner P.

Journal of Achievements in Materials and Manufacturing Engineering

|

2006

|

Vol. 14, nr 1-2

26--30

EN

Purpose: The aim of this study is to contribute to a better understanding of the role of the key factors governing the formation of multiphase TRIP aided steel. Design/methodology/approach: The present work reports the results of in-situ neutron diffraction experiments focused on monitoring the phase evolution in three TRIP steel samples subjected to different thermomechanical processing and mechanical loading to evaluate the stability of retained austenite. Findings: In-situ neutron diffraction experiments allowed characterizing the elastoplastic properties of the phases present in TRIP steel. These properties have strong influence on the transformation behaviour of the retained austenite during the straining and also critical effect on general mechanical properties of TRIP steel. Research limitations/implications: The precise, fast and cheap measurement of the amount of retained austenite in multiphase structure is a basic limitation for further research work, improvement and development control of TRIP steels. Practical implications: It is believed that not only the sufficient volume fraction of the retained austenite is the prerequisite to achieve convenient conditions for TRIP effect in low-alloyed steels. Originality/value: It was found that not only volume fraction of retained austenite has the influence on mechanical properties of TRIP steels, but also the state (size, distribution, carbon saturation, morphology) of retained austenite and the state of surrounding (α-matrix) plays important role.