仿晶界型铁素体/粒状贝氏体复相组织的韧性  

TOUGHNESS OF GRAIN BOUNDARY ALLOTRIOMOR-PHIC FERRITE/GRANULAR BAINITE DUPLEX MICROSTRUCTURE

作　　者：徐平光[1] 方鸿生[1] 白秉哲[1] 杨志刚[1] 

机构地区：[1]清华大学材料科学与工程系

出　　处：《金属学报》2002年第3期255-260,共6页Acta Metallurgica Sinica

摘　　要：研究了仿晶界型铁素体/粒状贝氏体复相钢轧态组织的韧性与裂纹扩展特点.与单一粒状贝氏体组织相比,仿晶界型铁素体/粒状贝氏体夏相组织具有更好的强韧性配合.适量仿晶界型铁素体的存在增加了复相组织的协调变形能力,提高了裂纹形成功;同时使裂纹扩展路径弯曲、分叉,微裂纹尖端钝化,在一定程度上提高了裂纹扩展功.在粒状贝氏体转变的第二阶段（富碳亚稳奥氏体→马氏体/奥氏体（M/A岛）缓冷,已转变的马氏体将进行自回火,并提高残余奥氏体的热稳定性,从而使复相组织的裂纹扩展功得到明显提高.The as-rolled toughness and crack propagation behavior of grain boundary allotriomorphic ferrite/granular bainite duplex microstructure were studied. In comparison with single granular bainite, the duplex microstructure obtained under the condition of conventional rolling possesses good strength-toughness combination. The presence of grain boundary allotriomorphic ferrite can increase the compatible deformation capability of duplex microstructure, improve the crack initiation energy under impact loading; it leads to the formation of crack branching and curving propagation route, has some blunting effect on microcrack tip, and improves the crack propagation energy to a certain extent. Slow air-cooling at the second stage of granular bainite transformation (carbon-rich metastable austenite -->martensite-austenite constituent) has certain self-tempering effect on the as-transformed martensite, increases the thermal stability of retained austenite, and results in the improvement of crack propagation energy of this duplex microstructure.

关 键 词：复相组织 仿晶界型铁素体 粒状贝氏体 裂纹扩展 韧性 合金结构钢 

分 类 号：TG142.41[一般工业技术—材料科学与工程]