Effect of manganese bands on austenite formation of low carbon steels in dual phase steel manufacture. (2021)

• Record Type: Journal Article
• Authors: Bandi, Bharath; van Krevel, Joost; Nandi, Sukalpan; Husain, Zulfiqar; Srirangam, Prakash
• Is Part Of: Materials today. Volume 41:Part 5(2021)
• Page Start: 1030
• Page End: 1034
• Publication Date: 2021
• Subjects: Dual phase steels -- Heating rate -- Austenite formation -- Manganese bands -- Morphology; Materials science -- Congresses -- Periodicals; 620.1
• DOI: 10.1016/j.matpr.2020.06.384
• Languages: English
• ISSNs: 2214-7853

Abstract

Abstract: A model has been developed to predict the heating rates required to obtain a specific amount of overlap between ferrite recrystallization and austenite formation in the heating step of dual phase steel manufacture. The predicted heating rates of 0.2, 7, 50.5 and 511 0 C/s were employed to heat the initial hot rolled steels to inter-critical temperature of 750 0 C for 60 sec followed by quenching to room temperature. The effect of manganese bands on the variation of through thickness austenite formation was systematically evaluated in this study. The Mn band spacing of the initial hot rolled samples was found to be 18.5 µm. Thermo-Calc simulations showed that the equilibrium austenite start temperature of the Mn enriched region is at least 70 0 C lower than the average composition. This variation in the composition and its corresponding austenite start temperature led to the formation of significant band structure of martensite at centre and random distribution at surface for all the heat-treated samples. Due to this, the micro-Vickers hardness values show significant through thickness anisotropy in all the samples. Moreover, with the increase in heating rates the potential nucleating sites of austenite decreased which led to the formation of thicker bands in the samples heat-treated at higher heating rates.