Nb对Fe-28Mn-10Al-C低密度钢组织与机械性能的影响

Effect of Nb on the Microstructure and Mechanical Properties of Fe-28Mn-10Al-C Low Density Steel

摘要:

开发制备了一种汽车用含Nb 0.5wt%的Fe-28Mn-10Al-C-0.5Nb低密度钢，旨在研究Nb在奥氏体Fe-Mn-Al-C低密度钢中的存在形态，以及Nb添加对Fe-Mn-Al-C低密度钢组织与力学性能影响。结果表明，Nb在Fe-28Mn-10Al-C-0.5Nb低密度钢中会以NbC的形式，分布于奥氏体晶内和晶界处。Fe-Mn-Al-C低密度钢中加入Nb后，奥氏体晶粒平均尺寸由39.49μm细化到13.67μm，并抑制退火孪晶形成。随着Nb添加，Fe-28Mn-10Al-C低密度钢的屈服强度和拉伸强度升高64-170MPa，断后伸长率升高11%，强度与延展性表现出良好平衡。加Nb低密度钢的高强度与高韧性与NbC析出相的沉淀强化和奥氏体细晶强化有关，且含Nb低密度钢屈服强度的升高主要由析出强化引起。

Abstract:

A novel Fe-28Mn-10Al-C-0.5Nb low density steel containing 0.5wt% Nb for automobile was developed, aiming to study the existence of Nb and the effect of Nb addition on the structure and mechanical properties of austenitic Fe-Mn-Al-C low-density steel. The results show that, Nb is distributed in austenite grains and grain boundaries in Fe-28Mn-10Al-C-0.5Nb low density steel in the form of NbC. With the addition of Nb, the average austenite grain size in Fe-Mn-Al-C low density steel is refined from 39.49μm to 13.67μm，and the formation of annealing twins is also suppressed by the addition of Nb. With the addition of Nb, the yield strength and ultimate tensile strength of Fe-28Mn-10Al-C low density steel increased by 64-170 MPa to the other, and the elongation after fracture increased by 11%, revealing an excellent balance of strength and ductility. This is due to the precipitation strengthening of NbC precipitates and fine grain strengthening of austenite. Precision strengthening plays main role to the increase of yield strength of Nb-added low density steel.