Vn Microalloying On The Organization And Performance Of Non-quenched And Tempered Steel

The history and the development trends of microalloyed steel in domestic and international industry are summarized, and the nitrogen-vanadium alloyed technology and its application status are further introduced in this paper. Adopting a large number of literatures on vanadium-nitrogen microalloyed steels, the main strengthening- toughening mechanisms was studied in this article.Precipitation in Non-quenched and Tempered steel was studied by optical microscopy, SEM and TEM and so on, Compared with alloying with FeV, F35MnVN steel alloyed with V-N was studied to evaluate the influence of V-N on microstructure and tensile properties of Non-quenched and Tempered steel.The conlusion was summarized as follow:(1) Non-quenched and Tempered steel added V have higher yield strength, tensile strength and better plasticity. The yield strength and tensile strength increase as the content of V, N increase. N added up 0.001%, the yield strength and tensile strength will increase by 6MPa and 5MPa. Plasticity decrease slightly with the content of V, N increase.(2)The microstructure of forged F35MnVN steel is "pearlite and ferrite",the volume fracture of pearlite can be more than 50%. Thinner pearlite can result in higher strength, roughness and plasticity.(3) More content of alloying element result in more precipitation and higher strength, morphology of precipitation was maily granule, The graininess occupies the great majority ,others occupie little. The precipitation has the functionsof grain refinement and precipitation strengthen.In a word,the effect of VN microalloying is superior to that of V microalloying, Evident nitrogen increasement result in vanadium usage saving in steel of same strength grade. Comparatively, microalloying with VN is more economy.