Microstructural evolution and tensile properties of low-carbon steel with martensitic microstructure during warm deforming and annealing

Yuwei Gao~(1,2)) Tianfu Jing~(1,2) Guiying Qiao~(1,2)) Jinku Yu~(1,2)) Tiansheng Wang~(1,2)) Qun Li~(2)) Xinyu Song~(2)) Shuqiang Wang~(2)) Hong Gao~(2)) 1)State Key Laboratory of Metastable Materials Science and Technology,Yanshan University,Qinhuangdao 066004,China 2)College of Materials Science and Engineering,Yanshan University,Qinhuangdao 066004,China

摘 要：<正>For preparing large-scale nano-grained and ultrafine-grained steel sheets by warm rolling and annealing,the effects of de- forming temperature on both the flow stress and the microstructure evolution of 09MnNiD steel with lath martensitic microstructure were studied by warm-compression test and transmission electron microscopy（TEM）observation.Thereafter,the steel with the lath martensitic structure was multi-pass warm-rolled and then annealed.TEM results indicate that nano-grained and ultrafine-grained steel sheets are formed by warm rolling at 400℃and annealing at 400-600℃.In comparison with the as-warm-rolled specimen,the tensile strength at room temperature changes a little when the rolled samples are annealed below 450℃,and the tensile strength is greatly lowered as the annealing temperature increases to above 550℃.

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