Mechanism of Improved Ductility of 1500 MPa-class Ultra-high Strength Cold-rolled Steel Sheet Produced by Rolling and Partitioning Method

DOI Web Site 3 Citations 31 References Open Access

Abstract

<p>By using a steel with standardized chemical composition and conventional manufacturing processes for flat-rolled steel strip, a 1500 MPa class stainless steel sheet, whose product of yield strength (YS) and total elongation (El) exceeds 30000 MPa%, was developed and its mass production was established. Besides the excellent YS–El balance, the developed steel sheet has excellent performance for not only an anti-secondary work embrittlement but also high cycle fatigue endurance.</p><p>Core technology of the developed method is composed of a combination of high precision cold-rolling and isothermal partitioning treatment in a batch furnace, named as a rolling and partitioning (R&P) method. By the R&P method, the microstructure of steel is controlled to the mixture of a strain-induced martensite as the matrix phase, and an optimum amount of retained austenite as the second phase which is dispersed in isolation and surrounded by the transformed martensite.</p><p>In this paper, the microstructure formation during the R&P process and the deformation mechanism that would bring about the excellent strength–ductility balance are discussed based on the results obtained from the in situ neutron diffraction measurement. The results have revealed that the typical Lüders-like stress–strain curve of R&P steel is caused by competitive plastic flow between austenite and martensite, and an effective transformation induced plasticity phenomenon.</p>

Journal

  • ISIJ International

    ISIJ International 60 (9), 2097-2106, 2020-09-15

    The Iron and Steel Institute of Japan

Citations (3)*help

See more

References(31)*help

See more

Related Projects

See more

Keywords

Details 詳細情報について

Report a problem

Back to top