700MPa级超低碳高强度贝氏体厚钢板的晶粒细化机制研究  

Grain refinement mechanism of a 700 MPa ultralow carbon bainite heavy plate steel

作　　者：夏政海[1] 曹志强[1] 罗登[1] 张永东[1] 刘凯[2] 吴开明[2] 

机构地区：[1]湖南华菱湘潭钢铁有限公司科技开发中心,湖南湘潭411101 [2]武汉科技大学冶金工业过程系统科学湖北省重点实验室,湖北武汉430081

出　　处：《武汉科技大学学报》2009年第3期264-269,共6页Journal of Wuhan University of Science and Technology

基　　金：湖北省自然科学基金计划青年杰出人才资助项目(2006ABB037);湘钢新产品研究与开发基金资助项目;教育部新世纪优秀人才支持计划资助项目(NCET-05-0680)

摘　　要：根据超低碳微合金化的成分设计意图,采用控制轧制和控制冷却工艺得到细化的贝氏体组织,利用光学显微镜、FE-SEM和TEM对各类微观组织和析出物进行了研究和分析。结果表明,700 MPa级超低碳贝氏体厚钢板为细小均匀的粒状贝氏体和少量针状铁素体与多边形铁素体的复合组织,其屈服强度不小于580MPa,抗拉强度不小于700 MPa,低温冲击韧性为-20℃,Akv不小于150 J。钢板具有强度高、韧性好和焊接性能良好的特点,其强度和韧性的良好匹配主要是由于在粒状贝氏体相变前形成了少量的针状铁素体分割奥氏体晶粒,从而细化了最终的复合组织。A fine grained bainite microstructure was obtained by means of an ultralow carbon and microalloyed steel design in conjunction with thermomechanical controlled process （TMCP）. The microstructure and precipitates were investigated by Olympus optical microscope, field emission scanning electron microscope （FE-SEM） and transmission electron microscope （TEM）. The results show that the mixed microstructure of granular bainite and a small amount of acicular ferrite and polygonal ferrite is observed in a 700 MPa ultralow carbon bainite microalloyed heavy plate steel. The yield strength and tensile strength of the plate is larger than those of 580 MPa and 700 MPa, respectively. The impact toughness Akv is larger than 150 J at -20 ℃. The plate has a good combination of high strength, good toughness and weldability. The good matching of high strength and good toughness should be attributed to the fine grained mixed microstructure consisting of granular bainite and acicular ferrite. The acicular ferrite, formed prior to granular bainite transformation, has effectively divided the austenite into many small regions, and consequently granular bainite transformed at lower temperatures is restricted in the small regions, which explains the microstructure refinement.

关 键 词：超低碳钢 贝氏体 针状铁素体 厚板 组织细化 

分 类 号：TG111[金属学及工艺—物理冶金] TG142[金属学及工艺—金属学]