Tool Steels. Austenitization and Carbide Dissolution of High Speed Tool Steel JIS-SKH51 in Short Time Heating.

Abstract

Recently, induction heating treatments have been applied to high alloy tool steels, for example JIS-SKH51. In rapid and short time heating, however, the influence of heating time and temperature on carbide dissolution and hardness is not fully clarified. The purpose of this study is to make clear the influence of these two factors on carbide dissolution and quenching-tempering hardness behavior of JIS-SKH51. Results obtained are as follows; 1) The initial stage of the holding at hardening temperature is characterized by the dissolution of small M 6 C carbides. 2) Increase of carbon and alloy elements in matrix before induction heating contributes to the increase in hardness in short time heating. 3) Finally, we applied induction hardening to two sizes of SKH51 forming rolls using the fundamental knowledge obtained in this study. Surface hardness higher than 65HRC and satisfactory hardened depth for each size of rolls were obtained..

W-Concentration 3D Mapping in SKH51 Steel by Dual-Energy K-Absorption Edge Subtraction Imaging

“…These correspond with the value reported in the reference. [14][15][16] The W-concentration in K-absorption edge subtraction imaging as shown in , as a threshold value should make carbide segmentation possible. However, the half value did not segment any carbide particle in this study due to the partial volume effect because carbide size was close to spatial resolution.…”

“…These particles are carbide that contains tungsten. [14][15][16] EDS analysis identified them as M6C or MC carbides. Bright particles observed in Fig.…”

“…The threshold value was changed on the basis of the standard value that was taken as the middle value between LAC value of matrix and LAC value of carbide that was estimated based on the chemical composition from references. [14][15][16] The segmented particles whose size is larger than 8 voxels, which can certainly recognize that it is particles, were analyzed to avoid image noise effects on the analysis results. Figure 10 shows changes of average Wconcentration at carbide particles with changing the segmentation threshold value.…”

Quantificação e identificação de carbonetos no aço ferramenta AISI/SAE M2

“…A análise preliminar dos perfis , FIG. 4.36, já havia mostrado que as bases dos picos apresentavam um alargamento discrepante com a largura a meia altura dos picos sugerindo uma possível distribuição bimodal de tamanhos de cristalito da mesma fase cristalina (Ozaki et al, 2000), que foi confirmada pelo refino conjunto da mesma fase cristalina considerando-se a distribuição bimodal segundo a estratégia proposta por Young e Sakthivel (1988). Tabela 4.9: Estequiometria e parâmetros de rede do carboneto MC.…”

“…Os carbonetos MC originados da dissociação do M 2 C já se formam esferoidizados, portanto o único mecanismo a atuar na homogeneização é o crescimento, que também neste caso é controlado pela difusão do vanádio na austenita presente.Estudos realizados porOzaki et al (2000) na esferoidização dos carbonetos, realizados na temperatura de 1200 °C, mostraram que em tempos superiores a um minuto ocorre crescimento significativo da fração de carbonetos e da dissolução dos carbonetos finos. , forneceu indícios valiosos de que o vanádio atuaria como formador de precipitados do tipo MC.…”