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Enhanced tensile properties of a reversion annealed 6.5Mn-TRIP alloy via tailoring initial microstructure and cold rolling reduction

journal contribution
posted on 2018-08-01, 00:00 authored by M Cai, H Huang, J Su, H Ding, Peter HodgsonPeter Hodgson
The feasibility of improving the overall performance of medium Mn steels was demonstrated via tailoring the initial microstructure and cold rolling reduction. The combined effects of cooling patterns after hot rolling (HR) and cold rolling (CR) reductions show: (1) as the cooling pattern varied from furnace cooling (FC) to oil quenching (OQ), the intercritically annealed microstructure was dramatically refined and the fraction of recrystallized ferrite dropped, regardless of CR reductions. This resulted in both high yield/ultimate tensile strengths (YS/UTS) but low total elongation to fracture (El); (2) as the CR reduction increased from 50% to 75%, the OQ-samples after annealing exhibited a more refined microstructure with relatively higher fractions of retained austenite and sub-structure, leading to higher YS and UTS but lower El; whereas the FC samples appeared to exhibit little difference in overall tensile properties in both cases. The differences in microstructural evolution with cooling patterns and CR reductions were explained by the calculated accumulated effective strain (εAES), which was considered to be related to degrees of recovery and recrystallization of the deformed martensite (α’). The optimal tensile properties of ∼1 GPa YS and ∼40 GPa·% UTS×El were achieved in the OQ-50%CR annealed samples at 650 °C for 1 h. This was quite beneficial to large-scale production of ultra-high strength steels, owing to its serious springback during heavy cold working.

History

Journal

Journal of materials science and technology

Volume

34

Issue

8

Pagination

1428 - 1435

Publisher

Elsevier

Location

Amsterdam, The Netherlands

ISSN

1005-0302

Language

eng

Publication classification

C1 Refereed article in a scholarly journal

Copyright notice

2017, Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology