Non-equilibrium solidification and microsegregation in centrifugally cast high speed steel for rolls

Klančnik, Urška; Kosec, Borut; Mrvar, Primož; Medved, Jožef

doi:10.2298/jmmb170109031k

Cited by 6 publications

(3 citation statements)

References 15 publications

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“…EDX analysis showed large chemical segregation of Mo, from 3–8 wt% in primary carbides and 1.9–2.9 wt% in eutectic carbides. Chemical segregation of alloying elements in as-cast rolls is common as a result of non-equilibrium conditions during solidification [ 36 ]. Figure 2 c shows a SEM micrograph of a typical carbide in which the Mo-rich region in carbide is bright.…”

Section: Resultsmentioning

confidence: 99%

Early Spalling Analysis of Large Particles in High-Cr Steel during Thermal Fatigue: Relevant Mechanisms

et al. 2022

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The aim of this study was to investigate the surface deterioration of high-Cr roll steel caused by the spalling of larger particles during thermal fatigue. The mechanisms of surface deterioration due to spalling of larger particles are discussed. Using a laboratory thermal fatigue test that replicates hot rolling conditions, samples were tested cyclically (up to 4500 times) at maximum cycle temperatures of 500, 600 and 700 °C, followed by water cooling. Specimens with surface deterioration were selected for analysis, revealing important influencing parameters, i.e., the combination of test temperatures, chemical composition, thermal stress and microstructural properties, leading to oxidation-assisted crack growth in different directions and consequent surface deterioration due to early spalling of larger particles. Here, we describe the mechanisms of crack propagation, especially in the lateral direction, and their relation to the subsequent spalling of larger particles, which depend on the influence of the local chemical composition on the microstructural constituents, as well as their distribution and properties. The results obtained in this study can be used in the development of roll steel microstructures with improved resistance to the identified mechanisms of surface degradation.

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Section: Resultsmentioning

confidence: 99%

Early Spalling Analysis of Large Particles in High-Cr Steel during Thermal Fatigue: Relevant Mechanisms

et al. 2022

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“…The measured M 2 C/M 6 C volume contents in the HSS HS_W + Mo and HS_Mo are distinctly higher than the thermodynamically calculated values. A reason for this deviation is that the as‐cast state can be referred to as a nonequilibrium state and the heat treatment with a duration of 30 min is not sufficient to transfer the microstructure into a state close to the thermodynamic equilibrium . A better agreement with the thermodynamically calculated values could probably be reached by subjecting the material to a hot deformation and by increasing the dwell time at hardening temperature to approach the thermodynamic equilibrium.…”

Section: Resultsmentioning

confidence: 99%

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

Egels

Wulbieter

Weber

et al. 2019

steel research int.

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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.

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“…In with the calculated and measured results. 29) Based on the analysis results from Figs. 6 to 9, it can be summarized in two points.…”

Section: Carbide Compositionmentioning

confidence: 99%

Carbide Characteristics of High Vanadium High-speed Steel Manufactured by Electroslag Remelting

et al. 2022

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The carbide characteristics of high vanadium high-speed steel (W3Mo4Cr5V6) manufactured by electroslag remelting (ESR) are analyzed by field emission scanning electron microscopy (FESEM), electron probe microanalysis (EPMA) and micro-Vickers. The results illustrate that three types of carbides are mainly formed in W3Mo4Cr5V6 which includes the lumpy and strip-like MC in the intracrystalline, lamellar M 2 C at grain boundary with discontinuous network and globular secondary carbides dispersed in matrix, among these, the eutectic strip-like MC occupies the main part. The more uniform distribution and finer size for both MC and M 2 C are obtained with high solidification rate (SR). Both 2D and 3D morphologies of MC carbides show obvious symmetry with clustered distribution and various shapes. The MC and M 2 C are rich in V and Mo, W respectively, the compositional characteristics are not only related to the carbide type and morphology, but also the precipitation order and distribution density. The Vickers hardness of primary MC, eutectic MC and M 2 C are measured and the average values are 2 205 HV, 850 HV and 896 HV respectively which includes the adverse effects of soft matrix on the test results of hard carbides. A new and exact test method for pure carbides should be developed in the future.

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Non-equilibrium solidification and microsegregation in centrifugally cast high speed steel for rolls

Cited by 6 publications

References 15 publications

Early Spalling Analysis of Large Particles in High-Cr Steel during Thermal Fatigue: Relevant Mechanisms

Early Spalling Analysis of Large Particles in High-Cr Steel during Thermal Fatigue: Relevant Mechanisms

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

Carbide Characteristics of High Vanadium High-speed Steel Manufactured by Electroslag Remelting

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