Abstract: The effects of niobium content (0.011% ~0.055% ) and heating temperature (1100 - 1250 ℃)on mi¬crostructure and properties of HRB400 steel rebar 20 mm plat are studied by thermal simulator Gleeble, high temperature la¬ser con-focal microscope and transmission electron microscope. In 20 mm plate with heating at 1180 °C for 1h, with in¬creasing 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, wliich corresponds to yield strength of 426 MPa, tensile strength of 685 MPa,elongation of 24. 0% and reduction of area 61.3%. 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 1180 °C.

Key words: Nb-Microalloying, HRB400 Steel, Heating Temperature, Perlite, Bainite 

摘要： 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(1100～1250℃)对HRB400钢20 mm板组织和性能的影响。结果表明,1180℃加热1h时20mm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;1180℃加热时铌含量析出物尺寸7～88 nm,呈弥散分布。

关键词: 铌微合金化, HRB400钢, 加热温度, 珠光体, 贝氏体