Abstract
Via traditional wire drawing,the medium carbon ferrite-pearlite(MCFP)steel wires can achieve the ultra-high strength beyond 4 GPa normally for high-carbon pearlitic steel wires,but have a 30-60％lower pro-duction cost.The microstructural evolution and mechanical properties of medium carbon ferrite-pearlite steel wires have been investigated by means of scanning electron microscopy,transmission electron mi-croscopy and tensile testing.The tensile strength of medium carbon ferrite-pearlite steel wires increases from 750 MPa up to 4120 MPa when the drawing strain increases up to ε=6.4,which represents the highest strength reported so far-to our knowledge for a carbon steel with such low carbon content.At low and medium strains(ε≤1.95),the proeutectoid ferrite forms dense dislocation walls(DDWs)via dislocation activities,including sliding,accumulation,interaction,and tangling.With the drawing strain increase,the reorientation of DDWs to the drawing direction forms the coarse proeutectoid ferrite lamel-lae.Finally,the proeutectoid ferrite deformed to high strains is characterized by a lamellar morphology and the average lamellar spacing of proeutectoid ferrite is about 55 nm at ε=6.4.The interlamellar spacing of pearlite and thickness of cementite decreases with the drawing strain increases.The disloca-tion density in ferrite lamellae increases with the drawing strain increases,and the dislocation density in ferrite lamellae is 7.8×1015 m-2 at ε=4.19.A higher dislocation density of 3.1 x 1016 m-2 can be obtained at ε=6.4 by means of extrapolation and TEM investigations.The stress contributions of proeutectoid ferrite and pearlite to the flow stress are estimated based on quantified structural parame-ters.Based on the assumption that the stress contributions from different strengthening mechanisms are linearly additive and the general rule of mixtures,a good agreement between the measured and esti-mated flow stresses has been found in a large range of flow stress.The good application of the general rule of mixture to the medium carbon ferrite-pearlite steel wires indicates the importance of quantitative characterization of microstructural evolution and parameters with the strain.
基金项目
Science and Technology Ad-vancement Program of Jiangsu Province,China(BA2017112)
Baosteel Golden Apple Project()
Industry-University Research Cooperation Project of Jiangsu Province,China(BY2018194)
European Research Council(ERC)under the Euro-pean Union Horizon 2020 research and innovation program(agreement No 788567-M4D)
VILLUM FONDEN(00028216)
NETL
NSTL
维普
万方数据