铌含量及铸锭加热温度对HRB400螺纹钢组织性能的影响

Effect of Niobium Content and Ingot Heating Temperature on Microstructure and Property of HRB400 Steel Rebar

利用Gleeble热模拟仪、高温激光共聚焦显微镜、透射电子显微镜研究了铌含量(0.011%~0.055%)及加热温度(1 100~1 250℃)对HRB400钢20 mm板组织和性能的影响。结果表明,1 180℃加热1 h时20 mm钢板中随铌含量增加,铁素体比例减少,贝氏体比例增加,屈服强度升高;铌含量0.024%时,组织中铁素体比例50.8%、珠光体比例39.0%,贝氏体比例10.2%,屈服强度426 MPa,抗拉强度685 MPa,伸长率24.0%,断面收缩率61.3%。铌析出物尺寸随加热温度升高逐渐细化,数量逐渐增多;1 180℃加热时铌含量析出物尺寸7~88 nm,呈弥散分布。

The effects of niobium content(0.011%~0.055%) and heating temperature(1 100~1 250℃) on microstructure and properties of HHRB400 steel rebar 20 mm plat are studied by thermal simulator Gleeble,high temperature laser con-focal microscope and transmission electron microscope.In 20 mm plate with heating at 1 180 ℃ for 1 h,with increasing content of niobium addition,the bainite content in steel increases to inhibit ferrite transformation,leads to increasing yield strength.Addition of 0.024% niobium,the microstructure has 50.8% ferrite,39.0% perlite and 10.2% bainite,which corresponds to yield strength of 426 MPa,tensile strength of 685 MPa,elongation of 24.0% and reduction of area61.3%.The size of niobium precipitates gradually refine with the increasing of heating temperature,the number is gradually increasing,and the disperse distributed niobium-containing precipitates with a size range of 7 ~88 nm can be produced at a heating temperature of 1 180℃.