Vanadium Microalloyed 0.25 C Cast Steels Showing As-Forged Levels of Strength and Ductility

Abstract

Application of cast steels instead of hot forged or rolled ones will significantly decrease manufacturing costs and the final product price. However, low levels of mechanical properties in cast steels, especially ductility, can slow down the substitution of forged and rolled steels with the cast. In the present work, the authors study the effect of 0.01-0.12 wt% vanadium additions on the microstructure and mechanical properties of 0.25 wt% C cast steels. The yield stress, ultimate tensile strength, and elongation to failure in the studied cast steels are 730-750 MPa, 955-1002 MPa, and 12.3-21.5%, respectively, which correspond to those in hot forged and rolled steels with similar compositions. So, high property values in the 0.25 wt% C cast steels are shown here for the first time. The simultaneous increase in strength and ductility with an increase in V content follow a decrease in pearlite fraction, interlamellar spacing, and average pearlite area size; an increase in amount of degenerated pearlite; an increase in V-rich particle volume fraction and number density in ferrite and pearlite; the occurrence of interphase precipitation (in 0.12 wt% V steel), and an increase in dislocation density in ferrite and pearlite.

Effect of cooling rates on the weld heat affected zone coarse grain microstructure

“…Due to high temperature, the initial tempered martensite microstructure of the as delivered steel undergoes austenite transformation into a CG HAZ. The grain growth, however, is retarded to some extent by the V(C, N) precipitate pinning effect, but unfortunately, vanadium precipitates dissolve quickly above Ac3 [8,9] If the cooling rate is high enough, martensitic or bainitic transformations from austenite take place, or both 10. In the absence of post-weld heat treatment microstructure of the single pass weld HAZ is effectively un-tempered.…”

The Effect of Size and Distribution of MnS Inclusions on the Austenite Grain Growth in a Low Cost Hot Forged Steel

“…Medium carbon hot forged steel has been widely used in the hot forging parts of automobiles, such as crankshafts and connecting rods, because it has the advantage of energy‐savings and high strength . Due to the lack of quenching and tempering process, the prior austenite grains of the products are very coarse, which deteriorates the final microstructures and impact properties.…”