Nb对热轧低碳贝氏体钢组织与性能的影响

Effect of Nb on microstructure and mechanical properties of hot-rolled low-carbon bainitic steel

为开发600 MPa级热轧贝氏体钢,设计了两种钢种成分,以C-Si-Mn系贝氏体钢为基础,添加一定合金元素Nb,经冶炼、轧制后进行了组织观察、析出沉淀分析以及性能测试试验,研究Nb元素在热轧贝氏体钢中的作用。结果表明,添加0.025wt%的Nb,能细化贝氏体板条,贝氏体板条短小,有利于提高钢的强度与韧性。弥散的含Nb碳氮化物颗粒析出,起到析出强化作用,提高钢的强度。Nb可明显改善低碳高强贝氏体钢的综合性能。

Two kinds of steels based on C-Si-Mn system were designed in order to develop the 600 MPa grade hot-rolled bainitic steel,one was Nb-added,and another as the base steel without Nb addition.Microstructure observation,precipitation analysis and tensile test were conducted to investigate the effect of Nb on microstructure and mechanical properties of the hot-rolled low-carbon bainitic steel after melting and rolling.The results reveal that the bainitic lath is refined by the 0.025 wt%Nb addition,and the strength and ductility of the steel are apparently increased.In addition,the dispersed carbonitride particles containing Nb provide the precipitation strengthening effect on the steel.It is concluded that the Nb addition improves the comprehensive performance of the low-carbon high-strength bainitic steel.