Comparative Effect of Mo and Cr on Microstructure and Mechanical Properties in NbV-Microalloyed Bainitic Steels

Abstract

Steel product markets require the rolled stock with further increasing mechanical properties and simultaneously decreasing price. The steel cost can be reduced via decreasing the microalloying elements contents, although this decrease may undermine the mechanical properties. Multi-element microalloying with minor additions is the route to optimise steel composition and keep the properties high. However, this requires deep understanding of mutual effects of elements on each other's performance with respect to the development of microstructure and mechanical properties. This knowledge is insufficient at the moment. In the present work we investigate the microstructure and mechanical properties of bainitic steels microalloyed with Cr, Mo, Nb and V. Comparison of 0.2 wt. % Mo and Cr additions has shown a more pronounced effect of Mo on precipitation than on phase balance. Superior strength of the MoNbV-steel originated from the strong solid solution strengthening effect. Superior ductility of the CrNbV-steel corresponded to the more pronounced precipitation in this steel. Nature of these mechanisms is discussed.

Microstructure Evolution during the Production of Dual Phase and Transformation Induced Plasticity Steels Using Modified Strip Casting Simulated in the Laboratory

“…Recent studies have shown that the improvement of tensile properties can also be achieved through the deformation in the austenite temperature region followed by accelerated cooling and warm deformation in the ferrite temperature region, leading to finer microstructures [38]. In addition, the microalloying with niobium, vanadium and molybdenum can also improve the tensile strength via precipitation and solid solution strengthening [39,40]. Thus, further research on the enhancement of tensile properties in DP and TRIP steels produced by the modified strip casting can be dedicated to the investigation of effects of thermo-mechanical control process and alloying.…”

Advances in Microalloyed Steels

“…The present Special Issue on Advances in Microalloyed Steels includes two review papers [1,2] and nine research papers [3][4][5][6][7][8][9][10][11]. In all of them, different combinations of microalloying elements are analyzed in terms of process, microstructure, and mechanical property modification.…”

“…The alternatives in microalloying are clearly reflected in terms of the grades studied in the different papers. Nb is present in many of them [1,2,5,7,8,10,11], alone or in combination with Mo [2,5,10], Ti [8], and V [10]. Two papers deal with Ti-Mo combinations [6,9], and the last two articles analyze the addition of V [4] and Al [3] as microalloying elements.…”

“…Even if some papers cover specific performance problems and optimization alternatives for industrial processing conditions [1,2,7,11], most of the papers deal with more fundamental analyses of the relationship between microstructure and mechanical properties [4][5][6]8,10]. Some papers also analyze the effect of microalloying on hot and cold working behaviors [3,9].…”

STUDY ON THE EFFECT OF COMPOSITION AND VARIATION OF Sn/Zn COOLING MEDIA ON NICKEL ALLOY STEEL THROUGH HOT FORGING AND AUSTEMPERING

“…From various experiments on methods to improve the mechanical properties of lateritic steel, austempering heat treatment, and alloying elements were chosen because they can form bainite microstructures with complex characteristics with optimal energy absorption capabilities. In previous research, the addition of Mo and Cr to is well known as element which provide phase balance strengthening by facilitating the formation of bainit structure, and solid solution strengthening [10][11]. Furthermore, in several studies have reported that austempering process which leads to bainitic or mixed bainite-martensite microstructures provides a better combination of mechanical properties, especially strength and impact toughness [12].…”