Development of Submicron/Nanostructured HSLA Steel Using Thermomechanical Treatment<br/>

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Development of Submicron/Nanostructured HSLA Steel Using Thermomechanical Treatment

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Type of Document: M.Sc. Thesis
Language: Farsi
Document No: 43529 (07)
University: Sharif University of Technology
Department: Materials Science and Engineering
Advisor(s): Karimi Tahri, Ali
Abstract:
Nanocrystalline steel was developed by severe cold-rolling and subsequent annealing of HSLA steel with an original microstructure of lath martensite. Specimens are austenitized at 1000 ºC for 30 min followed by quenching in brine. The quenched specimens are cold rolled with 80% to 90 % reduction and then annealed at temperatures from 400 to 700ºC for 10 to 120 min.The specimens annealed at temperature 500oC for 60 min showed the multiphased ultrafine structure composed of equiaxed ultrafine ferrite grains with the mean grain size of 180 nm, nano-carbides distributed uniformly and blocks of tempered martensite. The produced nanostructured steel exhibited a yield stress and UTS, of 1280 MPa and 1350 MPa, respectively which are about twice those of the as received steel, with 12% elongation
Keywords:
Martensite ; Nanostructure ; Cold Rolling ; Annealing ; High Strength Low Alloy (HSLA)Steel

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