Effect of Vanadium and Strain Rate on Hot Ductility of Low-Carbon Microalloyed Steels

Abstract

Hot tensile tests were conducted in this study to investigate the effect of strain rate (10−3 and 10 s−1) and vanadium content (0.029 and 0.047 wt.%) on the hot ductility of low-carbon microalloyed steels. The results indicate that a hot ductility trough appears at a low strain rate (10−3 s−1) because of the sufficient time for ferrite transformation and the growth of second particles, but it disappears at a high strain rate (10 s−1). The hot ductility is improved with the increase in strain rate at 700 °C or higher temperatures. In addition, with the increase in vanadium content, the large amounts of precipitate and increased ferrite transformation result in poor hot ductility of steels fractured at a low temperature range (600~900 °C). However, when the steel is fractured at a high temperature range (1000~1200 °C), more vanadium in the solid solution in the austenite inhibits the growth of parental austenite grains and results in grain refinement strengthening, slightly improving the hot ductility.

Hot Ductility, Homogeneity of the Composition, Structure, and Properties of High-Strength Microalloyed Steels: A Critical Review

“…Nb Negative [31] Nb, Nb-Ti, Nb-V [32,33] Ti-Mo [33] Hot ductility Nb Depends on size [34][35][36] Ti, Nb-Ti [37][38][39][40] V, Nb-V [41][42][43][44] This review presents a critical analysis of the data on the effect of precipitates of excess phases on the hot ductility and homogeneity of the chemical composition and microstructure of low-carbon microalloyed steels. In recent decades, considerable experience has been accumulated in ensuring a sufficient level of the hot ductility of steels, which is periodically systematized and summarized in the corresponding reviews [34,35,45,46].…”

“…In [47], it was also noted that the effect of vanadium on the hot ductility of steel was detected only with an increased vanadium content (0.095 wt.%) in a complex with a high nitrogen content (0.014 wt.%). Two steels with various vanadium contents, wt.%: 0.151 C-0.374 Si-1.520 Mn-0.047 Nb-0.020 Ti-0.029 V and 0.156 C-0.370 Si-1.601 Mn-0.047 Nb-0.020 Ti-0.041 V, were studied in [41]. Steel with a high vanadium content (0.041 wt.%) has a deeper trough: the smallest redaction of area is 66.5% at a fracture temperature of 700 • C, while steel with 0.029% V has 75.5%.…”

Hot Ductility Evolution Mechanism of Titanium‐Bearing Microalloyed Steels

“…Microalloyed steels with high strength and toughness by means of precipitation strengthening of alloying element carbonitride [ 1,2 ] and grain refinement under thermomechanical control process (TMCP) rolling are widely used in buildings, bridges, ships, and other industries. [ 3–6 ] However, the carbonitrides of microalloyed steels precipitated at the austenite grain boundaries of billets, enhance their crack sensitivity under an inappropriate cooling system, bending and straightening temperature in the continuous casting process, which induces the surface transverse corner cracks of billet.…”

Improving the Ionic Conductivity of Li1+xAlxTi2−x(PO4)3 in a Solid-State Synthesis by Regulating Li–O Bond with B3+ and Y3+

“…This secondary morphology can also be seen in other large-ionic-radii-Rare-Earth-elements-doping experiments. 62,63 The formation and segregation of the impurity phases YPO 4 in the Li 1.3+x Al 0.24 B 0.06 Ti 1.7−x Y x (PO 4 ) 3 and how Y substitution improves electrochemical performance will be discussed as follow.…”