Impact Toughness Scattering of Bainitic Steel in the Ductile-brittle Transition Temperature Region  

作　　者：石昆 CHEN Jiangbiao HOU Hong KONG Lingti LI Jinfu 张汉谦 

机构地区：[1]State Key Laboratory of Metal Matrix Composites,School of Materials Science and Engineering,Shanghai Jiao Tong University,Shanghai 200240,China [2]School of Materials and Metallurgy,Northeastern University,Shenyang 110004,China [3]Baosteel Research Institute,Baoshan Iron&Steel Co.,Ltd.,Shanghai 201900,China

出　　处：《Journal of Wuhan University of Technology(Materials Science)》2016年第3期636-643,共8页武汉理工大学学报（材料科学英文版）

基　　金：Sponsored by the National Basic Research Program of China(No.2011CB610405);the Reactor Material Development Research Project of Shanghai Baoshan Iron&Steel Research Institute(No.X08ECEJ190)

摘　　要：The impact toughness scattering in the ductile-brittle transition temperature （DBTT） region was experimentally examined on mixed and homogeneous grains of low alloy high strength bainitic steel under dynamic loading conditions. The results revealed that the mixed grain microstructure had larger impact toughness scattering than the homogeneous one, and the impact toughness scattering was mainly caused by the scattering in the cleavage fractttre stress σf. The value of σf. is related to the size of the microcrack formed in the bainitic packet. When a bainitic packet-sized microcrack propagates from one bainitic packet into the adjacent packet, cleavage fracture occurs. The cleavage fracture is controlled by the few coarse packets in the microstructures, and the σf scattering is influenced by the varied distances/relative locations between these coarse packets, and homogenizing the distribution of fine bainitic packet sizes is an effective way to reduce the impact toughness scattering in the DBTT region.The impact toughness scattering in the ductile-brittle transition temperature （DBTT） region was experimentally examined on mixed and homogeneous grains of low alloy high strength bainitic steel under dynamic loading conditions. The results revealed that the mixed grain microstructure had larger impact toughness scattering than the homogeneous one, and the impact toughness scattering was mainly caused by the scattering in the cleavage fractttre stress σf. The value of σf. is related to the size of the microcrack formed in the bainitic packet. When a bainitic packet-sized microcrack propagates from one bainitic packet into the adjacent packet, cleavage fracture occurs. The cleavage fracture is controlled by the few coarse packets in the microstructures, and the σf scattering is influenced by the varied distances/relative locations between these coarse packets, and homogenizing the distribution of fine bainitic packet sizes is an effective way to reduce the impact toughness scattering in the DBTT region.

关 键 词：bainitic steel low temperature impact toughness scatter cleavage fracture stress 

分 类 号：TG142.1[一般工业技术—材料科学与工程]