Thermodynamic Calculation for Silicon ModifiedAISI M2 High Speed Tool Steel

Abstract

During high speed tool steel production up to 0.2 wt % silicon is added, primarily to react with oxygen e.g. silicon acts as a de-oxidizer. If more than 0.2 wt % silicon is added, it serves to improve the deep hardening properties. An addition up to ~1 wt % silicon provides hardness and improves temper-stability but reduces the ductility. At high concentration, silicon causes embrittlement. Alloying with silicon raises the solubility of carbon in the matrix and hence the as-quenched hardness. It has virtually no influence on the carbide distribution, but it promotes the formation of M 6 C type carbides. The many essential alloy additions to iron (C, W, Mo, V, Cr, Si) make the high speed tool steel, HSS a complex multi-component system. Its complete experimental investigation would require enormous time and effort. Instead, the CALPHAD method has been successfully used for computation of phase equilibrium the multi-component HSS system. In the present work, the Thermo-Calc program has been applied to the system Fe-C-Cr-W-Mo-V-Si with the thermodynamic information contained in the solid-solution-database of the TCFE. In the present work, some temperature-concentration diagrams for silicon modified AISI M2 steel are presented by calculated quantities (melting and transformation temperatures, amount and compositions of phases). Calculated data are compared with standard AISI M2 high speed tool steel.

Pulsed plasma deposition of Fe-C-Cr-W coating on high-Cr-cast iron: Effect of layered morphology and heat treatment on the microstructure and hardness

“…(a) The coatings to be formed should have a higher content of strong carbide-forming elements in relation to their substrate, so that, higher carbide volume fractions (chromium rich carbides (M7C3, M23C6) or tungsten rich carbides (М6С, М2С)) and, consequently, a higher wear resistance could be attained. The solidus temperature of T1 steel was determined as the temperature of "L austenite + M6C" eutectic reaction [27], which had been estimated by Halfa [28] to take place at 1342 o C. This also follows from Fig. 2 which presents the equilibrium temperature-concentration phase diagrams of the systems Fe-18%W-4%Cr-1%V-C and Fe-28wt%Cr-2wt%Mn-1.3wt%Si-C, calculated using the Thermo-Calc software.…”

Computational Alloy Design for Process-Related Uncertainties in Powder Metallurgy

“…The avoidance of eutectic reactions provides a further design constraint. Equilibrium solidification paths for various type of HSS alloys are discussed in detail by Halfa [18] with the help of calculated phase diagrams. For example, in M2 type tool steels, the liquid phase at the sintering temperature transforms to either or M6C without the formation of deleterious eutectic carbides.…”

Comparison of the Microstructure of M2 Steel Fabricated by Continuous Casting and with a Sand Mould

“…The dendrite size and center shrinkage cavity are developed as a result of the slow cooling conditions. The cooling rate is key to the quality of M2 steel [19] and an appropriate cooling rate has a positive effect on relieving internal defects in the billet such as cracks and center shrinkage cavities [20,21].…”