Influence of plastic deformation on CCT-diagrams of low-carbon and medium-carbon TRIP-steels

• Autorzy: Grajcar A. , Opiela M.
• Języki publikacji: EN

Abstrakty

EN

Purpose: The aim of the paper is to investigate the influence of plastic deformation and cooling conditions on a structure and a shape of CCT-diagrams of new-developed TRIP-aided microalloyed steels. Design/methodology/approach: The diagrams of undeformed and plastically-deformed supercooled austenite transformations for low-carbon and medium-carbon microalloyed steels were determined. A part of the specimens were austenitized at a temperature of 1100*C, then slowly cooled to 900*C and next cooled to ambient temperature with a various rate from 1 to 300*C/s. To investigate the influence of plastic deformation on a shape of CCT (Continuous Cooling Transformations) diagrams, another part of the specimens were 50% deformed at 900*C and cooled to ambient temperature with a rate from 88 to 1*C/s. The DIL805A/D dilatometer, with a LVDT-type measuring head, was used to carry out dilatometric tests. Findings: It was found that a shape of CCT diagrams of elaborated steels predisposes them for multiphase sheets manufacturing. The new-developed steels possess ferritic and bainitic bays put forward to short times and pearlitic regions put aside. However, cooling the steel with a constant rate from austenitizing temperature doesn't lead to obtaining proper participation of ferrite. Plastic deformation of steel has a profitable influence on the shape of supercooled austenite curves. The region of γ-α transformation is translated to the left at simultaneous raise of start temperature of austenite into ferrite transformation resulting in definitely higher ferrite fraction. Moreover, significant refinement of microstructure in a whole range of cooling rate was also obtained. Research limitations/implications: To increase the ferrite fraction, modification of the cooling after hot-working finishing should be applied. In the fist stage, steel should be rapidly cooled in order to enter the range of γ-α transformation and successively slowly cooled in a range of γ-α transformation. Practical implications: The obtained CCT diagrams of supercooled plastically-deformed austenite transformations can be useful in a determination of cooling in the thermo-mechanical processing for TRIP-type steel sheets. Originality/value: The diagrams of the plastically-deformed supercooled austenite for TRIP-type microalloyed steels were obtained.

Słowa kluczowe

EN

metallic alloys; TRIP steel; CCT diagram; plastic deformation; supercooled austenite

PL

stopy metaliczne; odkształcenie plastyczne; austenit przechłodzony

• Wydawca: International OCSCO World Press
• Czasopismo: Journal of Achievements in Materials and Manufacturing Engineering
• Rocznik: 2008
• Tom: Vol. 29, nr 1
• Strony: 71--78
• Opis fizyczny: Bibliogr. 26 poz., il., wykr.

Twórcy

autor

Grajcar A.

autor

Opiela M.

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

Bibliografia

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