High-strength martensitic steels with low M_s temperature

• Autorzy: Bublikova D. , Masek B. , Jirkova H. , Jenicek S. , Ibrahim K. , Cubrova J.
• Języki publikacji: EN

Abstrakty

EN

Purpose: Various novel heat treatments and thermomechanical treatment procedures have been developed recently in order to enhance mechanical properties of high-strength steels. Design/methodology/approach: The new heat treatment process was tested on newly designed low alloy AHSS steels alloyed with manganese, silicon, chromium and alternatively molybdenum and nickel. Two different cooling rates of 16°C/s and 1°C/s showed that over a wide interval of cooling rates a hardened structure based on martensite and retained austenite can be achieved with an average hardness from 538 to 716 HV10 and ultimate strength in the range between 1837 and 2354 MPa. Findings: The main aim of these steels was to decrease the temperature M_f to below 100°C by quenching in a water or oil bath and use common industrial techniques. Manganese alloying was used for the required decrease of temperatures M_s and M_f. Silicon and chromium were used to increase the ultimate strength, silicon was used to eliminate the carbide formation and to support sufficient oversaturation of martensite. Practical implications: The industrial application of this process is complicated by the need for quenching in the range between M_s and M_f. The M_s temperature normally lies in the 200-250 °C interval. This is why new steels with low M_s temperature were selected for the experimental programme. Thanks to this feature, the steels could be quenched in water or polymer-based baths. The primary alloying elements of these four selected steels were manganese, silicon, molybdenum and chromium. Originality/value: The experimental heat treatment led to microstructures of martensite with retained austenite in all steels. Their strengths were in the range of 1750-2400 MPa and their A5 mm elongation levels were up to 10%. The morphology and distribution of retained austenite dictate the resulting mechanical properties of the material.

Słowa kluczowe

EN

Q-P process; retained austenite; AHSS; UHSS

PL

obróbka Q-P; austenit szczątkowy; AHSS; UHSS

• Wydawca: International OCSCO World Press
• Czasopismo: Archives of Materials Science and Engineering
• Rocznik: 2014
• Tom: Vol. 65, nr 2
• Strony: 53--57
• Opis fizyczny: Bibliogr. 6 poz.

Twórcy

autor

Bublikova D.

• FORTECH - Research Centre of Forming Technology, University of West Bohemia, Univerzitní 22, CZ – 306 14 Pilsen, Czech Republic

autor

Masek B.

• FORTECH - Research Centre of Forming Technology, University of West Bohemia, Univerzitní 22, CZ – 306 14 Pilsen, Czech Republic

autor

Jirkova H.

• FORTECH - Research Centre of Forming Technology, University of West Bohemia, Univerzitní 22, CZ – 306 14 Pilsen, Czech Republic

autor

Jenicek S.

• FORTECH - Research Centre of Forming Technology, University of West Bohemia, Univerzitní 22, CZ – 306 14 Pilsen, Czech Republic

autor

Ibrahim K.

• FORTECH - Research Centre of Forming Technology, University of West Bohemia, Univerzitní 22, CZ – 306 14 Pilsen, Czech Republic

autor

Cubrova J.

• FORTECH - Research Centre of Forming Technology, University of West Bohemia, Univerzitní 22, CZ – 306 14 Pilsen, Czech Republic

Bibliografia

• [1] X.Y. Long, F.C. Zhang, J. Kang, B. Lv, X.B. Shi, Low-temperature bainite in low-carbon steel, Materials and Science Engineering (in print).
• [2] H.K.D.H. Badeshia, R.W.K. Honeycombe, The Bainite Reaction, in: Steels: Microstructure and Properties, 3rd Edition, Elsevier, 2006, 129-154.
• [3] F.G. Caballero, H.K.D.H. Bhadeshia, Very strong bainite, Current Opinion in Solid State and Materials Science 8/3-4 (2004) 251-257.
• [4] B. Mašek, H. Jirková, D. Hauserová, L. Kučerová, D. Klauberová, The effect of Mn and Si on the properties of advanced high strength steels processed by quenching and partitioning, Materials Science Forum 654-656 (2010) 94-97.
• [5] H. Jirková, L. Ku􀃾erová, B. Mašek, Effect of quenching and partitioning temperatures in the Q-P process on the properties of AHSS with various amounts of manganese and silicon, Materials Science Forum 706-709 (2012) 2734-2739.
• [6] H. Jirková, B. Mašek, M.F.-X. Wagner, D. Langmajerová, L. Kučerová, R. Treml, D. Kiener, Influence of metastable retained austenite on macro and micromechanical properties of steel processed by the Q-P process, Journal of Alloys and Compounds (in print).