Enhancing mechanical properties of medium Mn advanced high-strength steel by inter-critical annealing: elimination of austenizing and quenching steps. (25th November 2020)

• Record Type: Journal Article
• Authors: Zabihi-Gargari, Mohammad; Shahverdi, Hamid Reza; Emami, Mohammad; Askari-Paykani, Mohsen
• Is Part Of: Ironmaking & steelmaking. Volume 47:Number 10(2020)
• Page Start: 1148
• Page End: 1160
• Publication Date: 2020-11-25
• Subjects: AHSS -- medium Mn -- boron -- hardenability -- microstructure -- mechanical properties -- martensite -- austenite; Iron industry and trade -- Periodicals; Steel industry and trade -- Periodicals; 669.1
• DOI: 10.1080/03019233.2019.1677038
• Languages: English
• ISSNs: 0301-9233

Abstract

ABSTRACT: Here, hardenability was enhanced by choosing two different chemical compositions, i.e. the addition of boron (0.12 wt-%) and chromium (2.5 wt-%) to the ordinary composition of the medium Mn advanced high-strength steels (AHSSs). Carbo-boride precipitates were formed in the samples having both boron and carbon in their compositions. Martensite was tempered after intercritical annealing at 700°C. In the alloy with both boron and carbon (A2 alloy), austenite was formed by 2.8 vol.-% after 10-min annealing. Primarily, the annealing process led to the austenite stabilization in the structure of the cold-rolled A2 alloy due to the dissolution of carbo-boride precipitates. For the carbon-free alloy (A1 alloy), on the other, the annealing process and subsequent dissolution of precipitates failed to create austenite stabilization. The resulting mechanical properties for the cold-rolled A2 alloy are ultimate tensile stress of 1029 MPa, total elongation per cent of 19.5 and formability index of 20 GPa%.