不同相区轧制对螺纹钢组织和性能影响

为了降低螺纹钢生产线坯料的生产成本,通过安装在16号轧机之后的预水冷装置对进入17号轧机的螺纹钢进行不同温度的控制,再经过17号和18号轧机对不同温度的螺纹钢进行轧制。探究了钢坯在不同相区进行轧制时对其组织性能的影响,结果表明,当钢种为HRB400-1NbS(Nb质量分数为0.025%)的螺纹钢在奥氏体未再结晶区轧制时(进入17号轧机的温度为(880±20) ℃),其屈服强度为437 MPa,抗拉强度为595 MPa;当钢种为HRB400-0NbS(Nb质量分数为0.015%)的螺纹钢在两相区轧制时(进入17号轧机的温度为(780±20) ℃),其屈服强度为435 MPa,抗拉强度为605 MPa;两者力学性能相差不大,这是因为HRB400-0NbS钢种在两相区轧制时,其晶粒度/级为10.5,相比HRB400-1NbS钢种在奥氏体未再结晶区轧制时晶粒度/级为9.5更加细小,通过细晶强化弥补了Nb所产出的第二相强化作用,为螺纹钢生产线坯料节约了每吨40~50元的成本。

Effect of different phase zones rolling on microstructures and properties of thread steels

To reduce the production cost of billet on rebar production line, the rebar entering No.17 rolling mill is controlled at different temperatures by the pre-water-cooling device which is installed after No.16 rolling mill, and then the rebars of different temperatures are rolled through No.17 and No.18 rolling mills. The effects of steel billet rolling in different phase regions on its microstructure and properties were explored. The results show that when the steel grade HRB400-1NbS (w(Nb) is 0.025%) rebar is rolled in the austenite unrecrystallized zone (the temperature entering the No.17 rolling mill is (880±20) ℃), its yield strength is 437 MPa, and its tensile strength is 595 MPa. When the steel grade HRB400-0NbS (w(Nb) is 0.015%) rebar is rolled in the two-phase zone (the temperature entering the No.17 rolling mill is (780±20) ℃), its yield strength is 435 MPa, and its tensile strength is 605 MPa. The mechanical properties of the two are not much different, this is because when the HRB400-0NbS rebar is rolled in the two-phase zone, its grain size/grade is 10.5, which is smaller than the 9.5 of HRB400-1NbS rebar when it is rolled in austenite unrecrystallized zone. It compensates the second phase strengthening effect produced of Nb by fine-grain strengthening, which saves a cost of 40-50 yuan per ton for the billets of rebar production line.