Title: Heat treatment of TRIP-aided bainitic steel

Authors: Jan Adamczyk, Adam Grajcar

Addresses: Deceased; formerly of Division of Structural and Special Materials Engineering, Institute of Engineering Materials and Biomaterials, Silesian University of Technology, ul. Konarskiego 18a, 44–100 Gliwice, Poland. ' Division of Structural and Special Materials Engineering, Institute of Engineering Materials and Biomaterials, Silesian University of Technology, ul. Konarskiego 18a, 44–100 Gliwice, Poland

Abstract: The heat treatment conditions for the medium-carbon steel strengthened by plastic deformation-induced martensitic transformation of the retained austenite (Transformation Induced Plasticity or TRIP) were developed. After heat treatment according to an optimum variant, the structure of the investigated steel is ferritic bainite, with a 23% fraction of retained austenite showing thermal stability. It was found that the bainite contains a very small fraction of carbides. Their precipitation is hampered by a Si concentration of 1.35%. The retained austenite occurs as regular grains of 3 µm in diameter or as films between bainite laths. On the basis of the tensile test, it was found that the steel is characterised by high strength properties (UTS = 1120 MPa, YS = 790MPa) and excellent ductile properties (TEL = UEL = 34%). The high strength and excellent ductile properties as well as the instantaneous work-hardening exponent n ~ 0.4 show that optimum utilisation of the TRIP effect improves the mechanical and technological properties of the steel.

Keywords: heat treatment; TRIP effect; bainitic steel; retained austenite; cooling conditions; mechanical properties; materials properties; plastic deformation; martensitic transformation; transformation induced plasticity.

DOI: 10.1504/IJMMP.2007.014305

International Journal of Microstructure and Materials Properties, 2007 Vol.2 No.2, pp.112 - 123

Published online: 30 Jun 2007 *

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