A Computational Approach to the Microstructural Design of High‐Speed Steels

Abstract

Increasing requirements concerning the operational conditions and durability of tools create a demand for the optimization of tool steels. High-speed steels (HSSs), for example, contain high amounts of carbides embedded in a secondary hardenable martensitic matrix. The wear behavior and the mechanical properties of HSS can be optimized for a certain application by adjusting the type and amount of carbides, as well as their compositions and the composition of the matrix. Computational thermodynamics based on the calculation of phase diagrams method allow the estimation of arising phases as well as phase compositions during the solidification or the heat treatment of a steel. However, in complex alloy systems, for example, HSS, the relationships between the content of alloying elements and the stability and the composition of phases can be complicated and nonlinear. Therefore, it can be difficult to find alloy compositions that are suitable to achieve a desired microstructure with iterative calculations. To handle this difficulty, a computational tool is developed, which determines compositions to obtain predefined HSS microstructures. The computational tool is based on a neural network that was previously trained with a thermodynamically calculated database. The efficiency of this approach is experimentally verified by producing and investigating laboratory melts of different HSS.

Study on the Tribological Behavior of Wear and Friction Coefficient on AISI M35 High-Speed Steel with and without DLC Coating

“…Table 1 shows the measured chemical composition. The result of this analysis was compared with the chemical composition found by other authors who studied the same material [24][25][26] , in addition to the ASTM A600 -Standard Specification for High Speed Steel Tools (Figure 2). The microstructure of the HSS was analyzed using scanning electron microscopy (SEM) on the TESCAN VEGA 3 equipment, equipped with array of tungsten filament, 300 nm resolution at 30 kV and 8 nm resolution at 3kV, with secondary electrons (SE) and scattered electrons (BSE), magnification of 2X-1,000.00X and electron beam energy from 2eV to 30kV.…”

“…The chemical composition of HSS showed an average of 0.86% carbon, an element that can vary between 0.70% and 1.60%. Carbon is the primordial alloy element, responsible for the formation of the martensitic matrix and the primary steel carbides and, as a consequence, the increase in hardness 26 . The presence of chromium improves the conditions of hardness and toughness, showing an average of 4.42% in the composition 28 .…”