Nb对0.2C-1.5Si-1.8Mn淬火配分钢组织和力学性能的影响

Influence of Nb on microstructure and mechanical properties of 0.2C-1.5Si-1.8Mn quenching and partitioning steel

在C-Si-Mn系传统Q&P钢的基础上,通过适当添加微合金元素Nb,探讨了微合金元素Nb对淬火配分钢组织性能的影响。结果表明,无Nb钢与加Nb钢的显微组织基本相同,均由铁素体、板条马氏体与M/A岛组成,但加Nb钢马氏体板条明显细化,板条间距明显减小。Nb促进铁素体析出并抑制珠光体生成,Nb的加入有效细化了组织,缩短了C配分距离,有利于碳向奥氏体中扩散,增加奥氏体的稳定性。经相同Q&P工艺处理后含Nb试验钢的屈服强度、抗拉强度均有所提高,其抗拉强度达989.07 MPa,伸长率为18.36%,强塑积为18.16 GPa·%。

Based on traditional C-Si-Mn Q&P steel,the influence of niobium(Nb)on microstructure and properties of quenchingpartitioning steel(Q&P)was investigated by adding moderate microalloying element Nb.The results show that the microstructure of the Nbadded steel consists of ferrite,lath martensite and M/A island,basically being the same as that of Nb-free steel.However,the martensite lath of the Nb-added steel is obviously refined,and the inter-lath spacing is significantly reduced.The addition of Nb promotes the precipitation of ferrite,inhibits the formation of pearlite,thus effectively refines the microstructure and shortens the carbon partitioning distance,facilitates the diffusion of carbon into austenite and increases the stability of austenite.The yield strength and tensile strength of the Nb-added steel are improved after the same Q&P heat treatment,with the tensile strength and elongation reaching to 989.07 MPa and18.36%respectively,the production of tensile strength and plasticity reaching up to 18.16 GPa·%.