Work

Formation of Ultrafine-Grained Dual-Phase Microstructure by Warm Deformation of Austenite in High-Strength Steel

Year: 2025

Type: article

Abstract: Thermomechanical processing by applying deformation-induced ferrite transformation (DIFT) is an effective method of producing ultrafine-grained (UFG) ferritic steels, which usually present high yield strength but low strain hardening. In this study, we explored the concept of DIFT in the processing of UFG dual-phase (DP) steel, in order to improve its strain hardening capability and thus its ductility. The processing temperature was reduced to enhance the dislocation storage in austenite. It was found that the warm deformation of austenite induced a dramatic occurrence of DIFT, resulting in the formation of UFG-DP microstructures along the whole thickness of the specimen. In the UFG-DP microstructure, the average ferrite grain size was 1.2 μm and the ferrite volume fraction was 44 vol.%. The observation of twinned martensite suggests the occurrence of carbon partitioning during the DIFT process. The UFG-DP microstructure exhibited a good combination of strength and ductility, which was enabled by the synergy of the ultrafine ferrite grains and the efficient composite effect. The outcome of this study provides a novel pathway to develop advanced hot-rolled steels with a UFG-DP microstructure and which are associated with the advantages of their readiness to be scaled up and low costs.

Source: Materials

DOI: 10.3390/ma18061341

Authors: Wen Shu, Yingqi Fan, Rengeng Li, Qing Liu, Qingquan Lai

Institutions: Nanjing Tech University, Jiangsu Industry Technology Research Institute

Language: English

Topic: Microstructure and Mechanical Properties of Steels

Subfield: Mechanical Engineering

Field: Engineering

Domain: Physical Sciences

Open Access status: gold

Estimated APC paid: $3,137

Funder: National Key Research and Development Program of China