The Preparation And Application Of Nanosized(NbTi)C/Fe Composite Powder

The steel has been recognized as high energy consumption and high emission industries,it is also an important means to break through the bottleneck of energy,resources and environment.In today's society,the economic is in the downturns,and the demands for steel performance is getting higher and higher.Methods to improve the performance of steel materials mainly includ: dislocation strengthening,fine grain strengthening,solid solution strengthening and second phase particle strengthening.The method for improving properties of iron and steel materials by adding particles has many advantages,this paper mainly studies the second phase particle strengthening,the(NbTi)C as the strengthening phase particles added to carbon steel in the solution in the process of melting,the effect of refining steel structure and strengthening the mechanical properties was finally achieved.By mechanical activation thermal synthesis method to perpared the nanometer(NbTi)C/Fe composite powder,and with electron microscope,scanning electron microscope and transmission electron microscope to study the effect of(NbTi)C particles for microstructure and properties of as-cast 45 steel.The result shows that the nano-(NbTi)C/Fe composite powder could be quickly prepared by the mechanical activation and thermal synthesis technique.The size of the nano-(NbTi)C particle is about 50~200 nm and could distributed uniformly in the Fe matrix.Adding nanometer(NbTi)C/Fe composite powder to 45 steel in the process of smelting,nano(NbTi)C is uniformly dispersed in the liquid phase,and played the role of the second phase particle reinforcement.nano(NbTi)C particles significantly refined as-cast microstructure,When the particle content is 0.71 wt%,the ferrite grain size is 19.6 ?m and reduced to the original steel 1/9.With the content of nanometer(NbTi)C increasing,the hardness and strength of 45 steel rised.The different content of(NbTi)C to the 45 steel has been under the normalizing refinement.The influence of the normalizing refinement and particle strengthening to the 45 steel shows the regular pattern.Compared with the as-cast,normalizing refined the group of steel.And the uniformity of the organization increased ignificantly.But the influence that normalizing process on the strength and hardness was unconspicuous.Undering the same process conditions,along with the content of the(NbTi)C particle increasing,the organization of 45 steel were refined and its strength increased.The change of hardness presents a parabola rule.When the content of the(NbTi)C was 0.28 wt %,the data reached the largest figure.