High Ductility and Toughness of a Micro-duplex Medium-Mn Steel in a Large Temperature Range from—196 ℃ to 200 ℃  

作　　者：Si-lian CHEN Jun HU Xiao-dan ZHANG Han DONG Wen-quan CAO 

机构地区：[1]Central Iron and Steel Research Institute [2]School of Materials Science and Engineering,Huazhong University of Science and Technology [3]Danish-Chinese Centre for Nanometals,Section for Materials Science and Advanced Characterization,Department of Wind Energy,Technical University of Denmark

出　　处：《Journal of Iron and Steel Research International》2015年第12期1126-1130,共5页

基　　金：Item Sponsored by National Natural Science Foundation of China(51371057,51261130091);National Basic Research Program of China(2010CB630803);Danish National Research Foundation(DNRF86-5)

摘　　要：A medium-Mn steel （0.2C5Mn） was processed by intercritical annealing at different temperatures （625 ℃ and 650 ℃ ）. An ultrafine-grained micro-duplex structure consisting of alternating austenite and ferrite laths was de- veloped by austenite reverse transformation （ART） during intercritical annealing after forging and hot rolling. Ultra- high ductility with a total elongation higher than 30% was achieved in the temperature range from -196 ℃ to 200 ℃, and high impact toughness no less than 200 J at -40 ℃ was obtained. Based on the analysis of microstructure and mechanical properties, it was found that the enhanced ductility was determined by the phase transformation effect of austenite （TRIP effect）, while the delayed ductile to brittle transition was controlled by austenite stability.A medium-Mn steel （0.2C5Mn） was processed by intercritical annealing at different temperatures （625 ℃ and 650 ℃ ）. An ultrafine-grained micro-duplex structure consisting of alternating austenite and ferrite laths was de- veloped by austenite reverse transformation （ART） during intercritical annealing after forging and hot rolling. Ultra- high ductility with a total elongation higher than 30% was achieved in the temperature range from -196 ℃ to 200 ℃, and high impact toughness no less than 200 J at -40 ℃ was obtained. Based on the analysis of microstructure and mechanical properties, it was found that the enhanced ductility was determined by the phase transformation effect of austenite （TRIP effect）, while the delayed ductile to brittle transition was controlled by austenite stability.

关 键 词：high strength high ductility intercritical annealing medium-Mn steel ultrafine grain size 

分 类 号：TG161[金属学及工艺—热处理] TQ334.9[金属学及工艺—金属学]