Nb-V、Nb-Ti对重型热轧H型钢强韧性的影响

Effects of Nb-V and Nb-Ti on strength and toughness of heavy hot-rolled H-beam

随着大型桥梁、高层建筑、海洋石油平台等的建设需求不断增加,翼缘厚度80 mm以上的重型热轧H型钢具有可观的市场前景。受其生产设备及工艺的影响,80 mm厚重型热轧H型钢的强韧性提升难度极大,微合金成分体系设计无疑是有效的突破点之一。对Nb-V、Nb-Ti成分体系对重型热轧H型钢强韧性的影响进行了对比研究。结果表明,Nb-Ti与Nb-V微合金化试验钢晶粒尺寸相当,但Nb-Ti微合金化试验钢的铁素体体积分数比Nb-V低约8%;Nb-Ti微合金化试验钢屈服强度、抗拉强度比Nb-V低30 MPa,-40℃低温冲击值比Nb-V低127 J;第二相粒子为Nb(C,N),分布均匀,随着合金元素添加量的增加,第二相析出数量增加,质点半径增大。

With the increasing demand for the construction of large bridges, high-rise buildings, offshore oil platforms, etc., heavy hot-rolled H-beam with a flange thickness of 80 mm or more has large market demand. Affected by its production equipment and technology, it′s extremely difficult to improve the toughness of the heavy hot-rolled H-beam with a thickness of 80 mm. Micro-alloy composition system design is one of the effective measures to solve this problem. The effects of Nb-V and Nb-Ti microalloying elements on the strength and toughness of heavy hot-rolled H-beam steels are studied. The results show that Nb-Ti and Nb-V microalloying test steels have similar grain sizes, but the ferrite volume fraction of Nb-Ti microalloying test steel is about 8% lower than that of Nb-V micro-alloying test steel. The yield strength and tensile strength of Nb-Ti microalloying test steel are 30 MPa lower than that of Nb-V microalloying test steel. The low-temperature impact value at-40 ℃ is 127 J lower than that of Nb-V microalloying test steel. The second phases are Nb(C, N), which are uniformly distributed, the quantity and radius of second phases are increased with the increase of alloying element content.