Study of Features of Phase Precipitate Formation, Structural State, and Properties of Nb, V-Microalloyed Low Carbon Ferritic Steels

Effect of the Chemical Composition on the Structural State and Mechanical Properties of Complex Microalloyed Steels of the Ferritic Class

“…In samples of steels containing molybdenum, except steel No. 5, a significant amount of austenitic carbide (carbonitride) precipitates of complex composition containing Nb and V is formed, which is consistent with the data of [23,28]. The number of such precipitates in rolled steel No.…”

“…6 having a complex microalloying system of V, Nb, Ti, and Mo. The presence of high concentrations of V, Mo and an increased Mn content facilitates the transformation of austenite to BF even at a low cooling rate, leading to the formation of an elongated shape of blocks and creates the conditions for the formation of a large number of austenitic and interphase precipitates based on V(C,N) [21,28]. This is in good agreement with the results of [7,23], which showed that a significant contribution to hardening is achieved due to the large number of nanoscale precipitates of vanadium carbide (carbonitride).…”

TEM Characterization of Complex Nanoprecipitates in Single-Phase V-Nb bearing Automotive Steels

“…These modern steel grades can present a tailor-made combination of high strength, ductility and complex formability performance, which stem from the lean compositional design and thermomechanical controlled processing (TMCP), which produce an essentially single-phase ferritic matrix strengthened by second-phase nanoprecipitates. These nanoprecipitates are mainly carbides (M x C y ) and/or carbonitrides (M x ,(C y ,N 1-y )), where M may be V, Nb, Mo, Ti or a combination [1,2]. These Face-Centered Cubic (FCC) carbides/carbonitrides are the crucial aspect of these steel grades hardening.…”

TEM Study of Nanoprecipitation and Dislocation Interactions in Novel Cold Rolled "Nano-Steel"

“…These modern steel grades can contribute a combination of high strength, ductility and improved complex formability performance [1]. Their characteristics stem from a suitable micro-alloying design and thermomechanical controlled processing (TCMP) that produce an essentially soft single-phase ferritic matrix strengthened by second-phase nanoprecipitates [1,2].…”

“…The most common additions of micro-alloying elements are Vanadium (V), Niobium (Nb), Molybdenum (Mo) and Titanium (Ti) that improve the precipitation hardening mechanisms of nano-steels by the formation of carbides (MXCY), nitrides (MXNY) and carbonitrides (MX,(CY,N1-Y)) in nano-scale [1,2]. Optimized TCMP routes of nano-steels strips are employed in the reheating, finishing rolling and coiling stages, coupled with suitable micro-alloying additions, to produce fine nano-precipitation to strengthen the ferritic matrix.…”