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Vol 11, Issue 1, 2016
Pages: 61 - 68
Research article
Metallic materials
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Published: 21.04.2016. Research article Metallic materials

MICROSTRUCTURE AND PROPERTIES OF KINETICALLY ACTIVATED BAINITE (KAB) STEELS

By
Peter Kirbiš ,
Peter Kirbiš
Contact Peter Kirbiš

Faculty of Mechanical Engineering, University of Maribor , Maribor , Slovenia

Mihael Brunčko ,
Mihael Brunčko

Faculty of mechanical engineering, University of Maribor , Maribor , Slovenia

Ivan Anžel
Ivan Anžel

Faculty of mechanical engineering, University of Maribor , Maribor , Slovenia

Abstract

KAB steels are a newly developed grade of advanced ultra high strength steels, which distinguish 
themselves by the rapid formation of fine nanostructured carbide free lower bainite. The term 
nanostructured is used with respect to the thickness of the individual bainitic ferrite plates which can 
vary between 50 nm to as fine as a few nanometers, depending on the temperature at which it was 
formed. This enables these steels to obtain desirable combinations of mechanical properties due to the 
presence of finely dispersed retained austenite which has been sufficiently stabilized via the formation 
of bainite under conditions where the precipitation of cementite is suppressed. Under the influence of 
stress and strain the retained austenite transforms into martensite and gives rise to microstructural 
hardening (Transformation induced plasticity effect), enabling such steels reasonable values of 
predominantly uniform elongation at strength levels of 2800MPa or higher. The aim of the current 
work is to present the concept of KAB steels, and the relations between their microstructure and 
mechanical properties. The feasibility of large scale industrial production of the new steel in also 
discussed. 

Funding Statement

The research work and has been supported by the National Research and Development Programme for long-term research within the framework of the Slovenian Research Agency.

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