The Transformation of Carbides during Austenization and Its Effect on the Wear Resistance of High Speed Steel Rolls

Abstract

The transformation of carbides with austenization time of a high speed steel (HSS) roll material, manufactured by a centrifugal casting method, has been studied. The correlation between wear resistance and the type, morphology, volume fraction, and distribution of the carbides has also been investigated. Microstructural observations, X-ray diffraction (XRD) analysis, hardness measurements, and energy dispersive spectroscopy (EDS) have been used to characterize the carbides. The type and volume fraction of carbides were found to change with austenizing time. During austenization, the transformation of the M 3 C carbides can be postulated as M 3 C + cFe fi M 2 C, with much finer nodular and rodlike MC carbides also forming through a solidstate transformation. The M 2 C carbide decomposes as M 2 C + c-Fe fi MC + M 7 C 3 + M 6 C. The decomposed carbide substantially maintains a platelike shape until the end of decomposition.

The Effect of Long-Time Austenization on the Wear Resistance and Thermal Fatigue Properties of a High-Speed Steel Roll

“…According to our previous research, [1] the long-time austenization can bring about changes in the type, morphology, volume fraction, and distribution of the carbides, which results in an improvement of the roomtemperature wear resistance. In this study, we made the HSS roll with the similar chemical composition and found the same microstructure evolution with increased austenization time shown as follows.…”

“…In this process, the overall carbide size decreases and the homogeneity of the carbide distribution increases. Consequently, the room-temperature wear resistance, [1] the high-temperature wear resistance, and the thermal fatigue properties are improved simultaneously. This finding should be of great use for the industrial production of HSS rolls and for the future improvement of properties of HSS rolls by controlling chemical composition, roller casting process, and the heat-treatment process.…”

“…[1,2] In general, when a large number of hard carbides are formed in a HSS roll, the resistance to wear can be improved, with a corresponding extended life of the roll. However, HSS rolls with a low matrix hardness and a small amount of carbides show better thermal fatigue properties than other HSS rolls.…”

The Effects of Austenitizing Conditions on the Microstructure and Wear Resistance of a Centrifugally Cast High-Speed Steel Roll

“…In addition, relatively soft M 2 C particles (1700 to 1900 HV) [3] are replaced by hard MC particles (2400 to 2600 HV) [24] at high austenitizing temperatures.…”

Composition Optimization and Experimental Characterization of a Novel Steel Based on CALPHAD

“…The HSS, which belongs to high carbon ledeburitic steel, contains more alloying elements such as W, Mo, Cr, V forming carbides including MC, M 2 C, M 6 C, M 7 C 3 and M 23 C 6 (Ref [10][11][12]. The extremely high hardness (HRC 63-70) can be obtained by special heat treatment, and the hardness and wear resistance can be retained up to 550-600℃ (Ref 13).…”