纳米尺度析出对低碳贝氏体钢组织与性能的影响  

Effect of nano-scale precipitates on microstructure and properties of ULCB steel

作　　者：杨跃辉[1] 

机构地区：[1]唐山学院机电工程系,河北唐山063000

出　　处：《金属热处理》2017年第5期58-61,共4页Heat Treatment of Metals

基　　金：河北省钢铁联合研究基金(E2014105091);河北省高等学校科学研究项目(ZC2016022);唐山市14中小企业发展资助项目(14130237B)

摘　　要：通过优化成分设计、热模拟试验及控轧控冷技术在试验轧机上得到了超细化的贝氏体组织,并采用金相显微镜和透射电子显微镜对超细组织的形貌及其亚结构进行了观察。结果表明:当非再结晶区压缩比达到8时,在厚度方向上原奥氏体晶界间距小于5μm,使得相变得到的贝氏体束尺寸显著减小,此时钢的抗拉强度达到1000 MPa、平均伸长率大于14%、-30℃冲击吸收能量达到120 J。透射电镜结果显示,此时单个贝氏体板条宽度小于200 nm,且在其内部存在高密度位错及纳米级胞状亚结构,而在位错上则分布着大量的尺寸小于10 nm的析出颗粒,其对位错产生强烈的钉扎作用,不但提高了钢的强度,而且也提高了胞状位错亚结构的稳定性,使得组织进一步细化,进而改善钢的综合力学性能。The ultra-fine bainitic microstructure was experimentally obtained through proper chemical composition design, thermal simulation test and thermo-meehanical control process （TMCP） on experimental rolling mill. The microstructure and substructure were observed by means of optical microscopy and TEM. The results indicate that the distance between the original austenite boundary in thickness direction is less than 5 μm, which leads to a obviously decreasing in the size of hainitic packets after transformation, when the compression ratio reaches 8 in non-recrystallization region. The excellent properties, that is, the tensile strength Rm 〉 1000 MPa, the elongation（ % EL） A 〉 14% and charpy notch impact Akv 〉 120J （ - 30℃） have been achieved. The results of TEM show that the width of single bainitic lath is less than 200 nm, in which the high density dislocations and cell shape substructure can be found. There are a large numbers of precipitation particles whose size is less than 10 nm distributing along the dislocations and pinning them, which not only increases the strength of tested steel, but also improves the stability of the cell shape substructure, so the mechanical properties of tested steel can be improved because of the more refined microstructure.

关 键 词：超细化贝氏体 控轧控冷 纳米级析出 位错亚结构 

分 类 号：TG142.4[一般工业技术—材料科学与工程]