Enhancing the Mechanical Properties of Vanadium-Microalloyed Medium-Carbon Steel by Optimizing Post-Forging Cooling Conditions

Abstract

The effects of different cooling conditions after forging on the microstructural characteristics and mechanical properties of a kind of high-content V-microalloyed medium-carbon steel 37MnSiVS were investigated. The effects were studied by using optical microscopy, transmission electron microscopy and tensile tests. Increasing direct cooling rate after forging is found to increase strength while slightly decrease ductility. A significant increase of strength could be obtained after forced air cooling and then short time isothermal holding at 873 K, while strength decreases gradually with further increasing holding time. The variations of microstructural characteristics especially V(C,N) precipitation strengthening effects with cooling conditions are mainly responsible for these variations of tensile properties. For the investigated high V-containing MA steel, a direct cooling strategy after finish forging is proposed, which includes accelerated cooling with forced air in ferrite range, following by short time isothermal holding or very slow cooling at around 873 K and then air cooling.

On the Influence of Vanadium on Air‐Hardening Medium Manganese Steels for Sustainable Forging Products

“…[ 21 ] However, it was also reported that vanadium addition leads to an increase in prior austenite grain size, which was explained by an interaction between titanium nitrides and vanadium carbides. [ 22 ] Another explanation for increased hardenability is that vanadium, when present in solid‐solution, shifts the diffusion‐controlled phase transformation to slower cooling rates, [ 23 ] especially during continuous cooling. [ 22 ]…”

Precipitation Behavior and Microstructural Evolution of Vanadium-Added TRIP-Assisted Annealed Martensitic Steel

“…The carbon atoms are easy to segregate at the phase boundaries . The deviation of carbon content between XRD and 3DAP data can be explained by the fact that the C content in retained austenite is determined by XRD under the simplified assumption that C segregating at dislocations does not occur . Moreover, the method with electromagnetic wave has low precision to measure intensity distribution of diffraction peak compared with 3DAP.…”

“…The alloying elements requirement of the TAM steel indicates that the chemical compositions similar to conventional TRIP‐assisted steels are appropriate . To investigate the precipitation behavior of V, different contents of V were added in the three experimental steels . The hot‐rolled steel sheets of 4 mm thickness were air cooled down to room temperature and cold rolled to the strip of 2 mm thickness after pickling in acid.…”

Low and Medium Carbon Advanced High-Strength Forging Steels for Automotive Applications

“…For every forging, post cooling rates decide the type of matrix structure, namely, quenching, rapid cooling, and moderate cooling resulting in martensite, bainite, and ferrite-pearlite matrix structures, respectively. Microalloying of V, Ti, and/or Nb contributes to the refining of prior austenitic grain and the precipitation strengthening of the matrix structure by V,Ti,Nb(C,N)-carbonitrides [8,[38][39][40][41][42][43][44][45]. Microalloying of Cr, Mo, Ni, B, etc.…”