控轧控冷对高强建筑用钢组织与性能的影响

对一种试验性的高强建筑用钢进行了控制轧制和控制冷却处理,研究了终冷温度对试验钢力学性能和显微组织的影响,并对拉伸断口形貌进行了观察。结果表明,试验钢在终冷温度为450℃时具有较高的强塑性和低屈强比,能够满足780 MPa级高层低屈强比建筑用钢的要求;在终冷温度为650℃时,试验钢中的M-A岛状组织更加粗大、含量相对较高,形状主要以多边形和和条带状形态为主,而终冷温度为450℃时,试验钢中M-A岛状组织的数量相对较多,尺寸相对细小,且主要以颗粒状形态存在;贝氏体铁素体基体上弥散分布着颗粒状M-A岛的复相组织有利于提高试验钢的强塑性并降低屈强比;终冷温度为450℃时试验钢的抗拉强度、规定塑性延伸强度、断后伸长率和屈强比分别为1070 MPa、825 MPa、16. 6%和0. 771。 

Effect of controlled rolling and controlled cooling on microstructure and properties of high strength building steel

Controlled rolling and controlled cooling treatment were carried out for a experimental high strength building steel. The influence of final cooling temperature on the mechanical properties and microstructure of the tested steel was studied,and the tensile fracture surface was observed. The results show that when end cooled at 450 ℃,the tested steel has high strength,high plasticity and low yield ratio,which can meet the requirements of 780 MPa low yield ratio building steel for high rise buildings. When the end cooling temperature is 650 ℃,MA island structure in the experiment steel is more bulky and of relatively high content,mainly in polygon shape and banded morphology.When the end cooling temperature is 450 ℃,the number of M-A islands in the tested steel is relatively large,while their size is relatively small,and mainly in granular form. The dispersion of granular M-A island complex on bainite ferrite matrix is beneficial to enhance the strength,plasticity and to reduce the yield ratio of the tested steel. The tensile strength,proof strength at 0. 2% plastic extension,elongation after fracture and yield ratio are 1070 MPa,825 MPa,16. 6% and 0. 771 when the end cooling temperature is 450 ℃.