Thermal processing of CMnAlSi steel at (α+γ) temperature range

• Autorzy: Gajda B. , Lis A. K.
• Języki publikacji: EN

Abstrakty

EN

Purpose: Investigations of microstructure changes in the modern high-strength CMnAlSi steel after austenitization at (α+γ) temperature 900°C/60s were presented in order to determine the influence of the cooling rate on the phase transformations and obtaining multiphase TRIP-aided microstructure. Also the effect of alloying elements on the Ac1 and A c3 temperatures and the volume fractions of austenite in various (α+γ) austenitization temperatures for the investigated steel were presented. Design/methodology/approach: Thermo-calc program was used in order to determine influence of alloying elements such as Al, Si on Ac1 and A c3 temperatures. Dilatometric experiments of the CMnAlSi steel were done for the temperature 900°C from (α+γ) temperature range. Microstructures were investigated by light optical microscopy and scanning electron microscopy. The amount of retained austenite in the obtained microstructures was investigated with X-ray diffraction technique. The quantitative analysis of phases in microstructure were done using Image pro Plus computer program. Mechanical properties of investigated steel were examined. Findings: The multiphase microstructure containing about 10% retained austenite can be obtained in steel of 0.15 % C, 1.55 % Mn, 1% Si and 1% Al through continuous cooling from 900°C/60s to the room temperaturę without isothermal holding at bainitic transformation temperature range. Practical implications: Steel CMnAlSi is well suited for production of TRIP grade in a large range of temperatures from 800°C to 900°C at the cooling rates of about 10°C /s to 40°C/s. The amount of 50 % austenite at temperature 900°C allows for production of TRIP microstructure with stable retained austenite. Originality/value: The TRIP steels can be processed only if annealing parameters are perfectly adjusted to the chemical composition of the steel. The A c1 and A c3 temperatures differ for the various chemical compositions and they strongly depend on the C, Si and Al contents. It is hard to match the same annealing temperature for every TRIP steel grade. Also the cooing rate has an important role in obtaining the proper multiphase TRIP microstructure with stable retained austenite.

Słowa kluczowe

EN

heat treatment; automotive steel; quantitative analysis

PL

obróbka cieplna; stal samochodowa; analiza ilościowa

• Wydawca: International OCSCO World Press
• Czasopismo: Journal of Achievements in Materials and Manufacturing Engineering
• Rocznik: 2006
• Tom: Vol. 18, nr 1-2
• Strony: 355--358
• Opis fizyczny: Bibliogr. 5 poz., rys., tab., wykr.

Twórcy

autor

Gajda B.

• Institute of Materials Egineering; Faculty of Materials Processing Technology and Applied Physics; Częstochowa University of Technology; Al. Krajowej 19; 42-200 Częstochowa; Poland

autor

Lis A. K.

• Institute of Materials Egineering; Faculty of Materials Processing Technology and Applied Physics; Częstochowa University of Technology; Al. Krajowej 19; 42-200 Częstochowa; Poland

Bibliografia

• [1] K. Sugimoto, T. Muramatsu, T. Hojo, S. Hashimoto, Y. Mukai, Ultra High-Strength C-Si-Mn-Nb-Mo TRIP-Aided Sheet Steels,materials Science & Technology (2005) 15-24.
• [2] J.E. Garcia-Gonzalez, C.I. Garcia, M. Hua, A.J. DeArdo, Fundamental study of the austenite formation and decomposition in high strength low-Si, Al aided Nb-Mo TRIP steels, Materials Science & Technology, 2005, p. 3-14.
• [3] J. Mahieu, D van Dooren, L. Barbe, B.C. De Cooman, Influence of Al, Si and P on the kinetics of intercritical annealing of TRIP-aided steels: thermodynamical prediction and experimental verification, Steel Research 73 (2002) No.6+7, p. 267-273.
• [4] A. Pichler, S. Traint, G. Arnolder, P. Stiaszny, M. Blamschein, High strength hot-dip galvanized steel grades: A critical comparison of alloy design, line configuration and properties, I&SM, 2003, p. 21-31.
• [5] A.K. Lis, B. Gajda, A.J. De Ardo, New Steel Chemistry Design for TRIP and Dual-Phase Structures, Developments in Sheet Products for Automotive Applications, Materials Science & Technology, 2005, p. 47-52.