Segregation of alloying elements in thermomechanically rolled medium-Mn multiphase steels

• Autorzy: Grajcar A. , Kamińska M. , Opiela M. , Skrzypczyk P. , Grzegorczyk B. , Kalinowska-Ozgowicz E.
• Języki publikacji: EN

Abstrakty

EN

Purpose: The aim of the paper is to assess the tendency of alloying elements to macro- and microsegregation during hot-forging and successive thermomechanical rolling of medium-Mn Al-bearing steel sheets. Design/methodology/approach: The macro- and microsegregation of alloying elements was assessed by EDS and WDS measurements across the thickness of the roughly-forged flats and thermomechanically processed 3.3 mm sheets. The microstructure was revealed using combined methods of optical microscopy (OM) and scanning electron microscopy (SEM). Morphological features of microstructural constituents were discussed with focusing on retained austenite. Findings: It was found that the final multiphase microstructure is mainly dependent on the Mn content and the effect of Nb microaddition is relatively low. The 3Mn steels possess very fine bainite-based microstructures whereas the steels containing 5% Mn are characterized by lath bainitic-martensitic microstructures. All the steels contain retained austenite as fine granules or layers located between bainitic ferrite laths. Some fraction of martensite-austenite (M-A) islands was also identified. The tendency of Mn and Al to macrosegregation was found after the initial hot-forging. It disappears after successive rough and thermomechanical rolling whereas thin martensite and martensite-austenite microbands as a result of Mn microsegregation locally occur. Research limitations/implications: Further investigations are required to quantify the local changes of chemical composition especially in formed microbands and X-ray quantitative phase analysis should be applied to assess a fraction of retained austenite. Practical implications: The knowledge of the macro- and microsegregation of alloying elements in advanced medium-Mn steels containing retained austenite can be useful in designing the thermomechanical rolling procedures of multiphase steel sheets. Originality/value: A problem of macro- and microsegregation of Mn and Al in advanced high strength steels, which belong to the third generation of automotive steels was discussed with concentrating on Mn and Nb microaddition effects.

Słowa kluczowe

EN

metallic alloys; thermomechanical rolling; multiphase steel; retained austenite; macrosegregation

• Wydawca: International OCSCO World Press
• Czasopismo: Journal of Achievements in Materials and Manufacturing Engineering
• Rocznik: 2012
• Tom: Vol. 55, nr 2
• Strony: 256--264
• Opis fizyczny: Bibliogr. 30 poz., rys., tab.

Twórcy

autor

Grajcar A.

• Institute of Engineering Materials and Biomaterials, Silesian University of Technology, ul. Konarskiego 18a, 44-100 Gliwice, Poland

autor

Kamińska M.

• Institute of Non-Ferrous Metals, ul. Sowińskiego 5, 44-100 Gliwice, Poland

autor

Opiela M.

• Institute of Engineering Materials and Biomaterials, Silesian University of Technology, ul. Konarskiego 18a, 44-100 Gliwice, Poland

autor

Skrzypczyk P.

• Institute of Engineering Materials and Biomaterials, Silesian University of Technology, ul. Konarskiego 18a, 44-100 Gliwice, Poland

autor

Grzegorczyk B.

• Institute of Engineering Materials and Biomaterials, Silesian University of Technology, ul. Konarskiego 18a, 44-100 Gliwice, Poland

autor

Kalinowska-Ozgowicz E.

• Institute of Engineering Materials and Biomaterials, Silesian University of Technology, ul. Konarskiego 18a, 44-100 Gliwice, Poland

Bibliografia

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