摘要
控制轧制调控奥氏体组织状态,对直接淬火高强钢的组织与性能至关重要。以EH500高强海工钢为研究材料,探讨控制轧制工艺对其直接淬火后微观组织与力学性能的影响。钢板经过不同温度控制轧制后,分别在温度为780、820、860℃时开始直接淬火,并在550℃进行回火热处理。结果显示,随着直接淬火温度升高,显微组织由带状分布变成均匀分布,铁素体体积分数由60%减少至20%,贝氏体体积分数则从40%增加到80%,晶粒尺寸从5.0µm增加到5.4µm,大角度晶界密度由0.34µm^(-1)增加至0.41µm^(-1),织构组元从变形织构{113}〈110〉和{332}〈113〉演变成旋转立方织构,并且织构强度从8.92大幅降低至3.26和2.64。回火对显微组织形态、铁素体与贝氏体比例、晶粒尺寸和织构组元类型影响很弱,但将马氏体/奥氏体组元转变成碳化物,并使角度晶界密度增加至0.37~0.42µm^(-1),也使织构强度降低至3.88、2.71和1.82。直接淬火温度升高将屈服强度从438 MPa提高到509 MPa和529 MPa,但将-40℃冲击功从87 J降低到84 J和56 J。550℃回火后,屈服强度分别增加至526、556、560 MPa,-40℃冲击功分别提高至237、266、256 J,均满足EH500钢强度和冲击韧性指标要求。
Controlled rolling controls the austenite state,which is essential for the microstructure and properties of direct-quenched high-strength steel.EH500 high-strength steel was focused on to examine how variations in controlled rolling parameters affect its microstructure and mechanical properties following online direct quenching.After controlled rolling at different temperatures,the steel plates were directly quenched starting at 780,820 and 860℃,followed by tempering heat treatment at 550℃.Results show that as the direct quenching temperature increases,the microstructure changes from banded to uniform distribution,with the volume fraction of ferrite decreasing from 60%to 20%and bainite increasing from 40%to 80%.The grain size increases from 5.0µm to 5.4µm,and the high-angle grain boundary density increases from 0.34µm^(-1) to 0.41µm^(-1).The texture components evolve from deformation textures{113}〈110〉and{332}〈113〉to rotated cube texture,with the texture intensity significantly decreasing from 8.92 to 3.26 and 2.64.Tempering has a weak effect on the microstructure morphology,ferrite-to-bainite ratio,grain size,and texture component types,but it transforms martensite/austenite constituents into carbides,increases the high-angle grain boundary density to 0.37-0.42µm^(-1),and reduces the texture intensity to 3.88,2.71,and 1.82.Increasing the direct quenching temperature can raise the yield strength from 438,509 and 529 MPa,but lower the impact energy at-40℃from 87 J to 84 J and 56 J.After tempering at 550℃,the yield strength increases to 526,556 and 560 MPa,while the impact energy at-40℃improves to 237,266 and 256 J,respectively,all meeting the strength and impact toughness requirements for EH500 steel.
作者
罗登
朱拓
高海亮
肖大恒
李艳梅
叶其斌
LUO deng;ZHU Tuo;GAO Hailiang;XIAO Daheng;LI Yanmei;YE Qibin(Huna Valin Xiangtan Iron and Steel Co.,Ltd.,Xiangtan 411101,Hunan,China;The State Key Laboratory of Rolling and Automation,Northeastern University,Shenyang 110819,Liaoning,China)
出处
《钢铁》
北大核心
2025年第3期104-116,共13页
Iron and Steel
关键词
EH500海工钢
控制轧制
直接淬火
显微组织
织构
晶界取向差
强度
韧性
EH500 steel for offshore
controlled rolling
direct quenching
microstructure
texture
grain boundary misorientation
strength
toughness
