The effect of niobium on the microstructure and phase transformation kinetics in low-carbon Medium Manganese Steels

Patrick Peißl, Reinhold Schneider, Manfred Rahofer, Ludovic Samek, Enno Arenholz

Publikation: Beitrag in Buch/Bericht/TagungsbandKonferenzbeitrag

2 Zitate (Scopus)

Abstract

Medium-Mn steels are a promising candidate to fulfil the requirements of the 3rd generation of AHSS (Advanced High Strength Steels) which combine high strength and high ductility. A new approach is to add micro alloying elements, like niobium, to affect microstructural development during recrystallization and phase transformations. Using a quenching dilatometer, the kinetics of the phase transformations from austenite (810 °C and 840 °C) to its transformation-products by varying different cooling rates (100 K/s to 0.03 K/s) were investigated for two low carbon medium-manganese steels with different contents of niobium. Based on the dilatometric curves, the results of light optical microscopy (LOM) and quantitative metallography, measurements of the retained austenite (RA) content by X-ray diffractometry (XRD) and hardness measurements, continuous-cooling-transformation (CCT) diagrams were constructed. Furthermore, the influence of the element niobium on the microstructure after intercritical annealing was investigated by similar methods. Different etching-methods (Nital, Klemm-I) were applied to reveal different microstructural aspects. Besides considerable grain-refinement effects with increased niobium content, the phase-transformations were accelerated in the CCT-diagrams. The microstructure varies from 100 % martensite to certain amounts of bainite, but also ferrite at lower cooling rates. Intercritical annealing results in different amounts of retained austenite.

OriginalspracheEnglisch
TitelEuropean Conference on Heat Treatment 2015 and 22nd IFHTSE Congress - Heat Treatment and Surface Engineering from Tradition to Innovation, 2015
Seiten267-275
Seitenumfang9
Band70
DOIs
PublikationsstatusVeröffentlicht - Dez. 2015
VeranstaltungEurop. Conf. on Heat Treatment 2015 & 22nd IFHTSE Congress - Venice, Italien
Dauer: 20 Mai 201522 Mai 2015

Publikationsreihe

NameHTM - Journal of Heat Treatment and Materials
Herausgeber (Verlag)Carl Hanser Verlag GmbH & Co. KG
ISSN (Print)1867-2493

Konferenz

KonferenzEurop. Conf. on Heat Treatment 2015 & 22nd IFHTSE Congress
Land/GebietItalien
OrtVenice
Zeitraum20.05.201522.05.2015

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