Abstract
The influence of Ta addition on the solidification microstructure, solute distribution and hardness after quenching and tempering treatments was investigated for a high-carbon high-speed steel type cast alloy (Fe1.9% C0.5% Mn4.9% Cr5.0% Mo5.07.2% V0.41.4% Ta). The compositions of Vand Ta were systematically changed to improve the distribution of hard MC carbides in the hypoeutectic range. Electron probe micro-analysis (EPMA) and X-ray diffraction (XRD) identified an oval microstructure as MC carbides containing mainly V and Ta, and a lamellar structure as M 2C carbides containing mainly Fe and Mo among the austenite (γ) dendrites. Redistribution of alloying elements during the solidification sequence of primary γ, γ + MC and M2C eutectic structure could be calculated from the Scheil-Gulliver equation and the initial composition. The macro-hardness of the quenched specimens gradually increased with increasing quenching temperature until a maximum was reached. This indicates that macro-hardness of the quenched specimens depends on both the amount and hardness of martensite matrix. All specimens which were tempered at 723873K showed secondary hardening. Furthermore, hardening of the specimens was most apparent when specimens containing large amounts of retained γ were tempered at an optimum temperature. For example, the hardness of specimens with added Ta increased to around 900HVafter tempering at 823 K. These results suggest that the macro-hardness of tempered specimens is governed by the maximum amount of carbon in the γ matrix at quenching temperature, the degree of transformation from retained γ to martensite, and the precipitation and distribution of secondary carbides.
| Original language | English |
|---|---|
| Pages (from-to) | 354-361 |
| Number of pages | 8 |
| Journal | Materials Transactions |
| Volume | 53 |
| Issue number | 2 |
| DOIs | |
| Publication status | Published - Mar 21 2012 |
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All Science Journal Classification (ASJC) codes
- Materials Science(all)
- Condensed Matter Physics
- Mechanics of Materials
- Mechanical Engineering
Cite this
Solidification microstructures and quench/temper hardness of tantalum added high-carbon high-speed steel type cast alloy+1. / Narita, Ichihito; Sakamoto, Souichi; Miyahara, Hirofumi; Yamamoto, Kaoru; Kamimiyada, Kazunori; Ogi, Keisaku.
In: Materials Transactions, Vol. 53, No. 2, 21.03.2012, p. 354-361.Research output: Contribution to journal › Article
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TY - JOUR
T1 - Solidification microstructures and quench/temper hardness of tantalum added high-carbon high-speed steel type cast alloy+1
AU - Narita, Ichihito
AU - Sakamoto, Souichi
AU - Miyahara, Hirofumi
AU - Yamamoto, Kaoru
AU - Kamimiyada, Kazunori
AU - Ogi, Keisaku
PY - 2012/3/21
Y1 - 2012/3/21
N2 - The influence of Ta addition on the solidification microstructure, solute distribution and hardness after quenching and tempering treatments was investigated for a high-carbon high-speed steel type cast alloy (Fe1.9% C0.5% Mn4.9% Cr5.0% Mo5.07.2% V0.41.4% Ta). The compositions of Vand Ta were systematically changed to improve the distribution of hard MC carbides in the hypoeutectic range. Electron probe micro-analysis (EPMA) and X-ray diffraction (XRD) identified an oval microstructure as MC carbides containing mainly V and Ta, and a lamellar structure as M 2C carbides containing mainly Fe and Mo among the austenite (γ) dendrites. Redistribution of alloying elements during the solidification sequence of primary γ, γ + MC and M2C eutectic structure could be calculated from the Scheil-Gulliver equation and the initial composition. The macro-hardness of the quenched specimens gradually increased with increasing quenching temperature until a maximum was reached. This indicates that macro-hardness of the quenched specimens depends on both the amount and hardness of martensite matrix. All specimens which were tempered at 723873K showed secondary hardening. Furthermore, hardening of the specimens was most apparent when specimens containing large amounts of retained γ were tempered at an optimum temperature. For example, the hardness of specimens with added Ta increased to around 900HVafter tempering at 823 K. These results suggest that the macro-hardness of tempered specimens is governed by the maximum amount of carbon in the γ matrix at quenching temperature, the degree of transformation from retained γ to martensite, and the precipitation and distribution of secondary carbides.
AB - The influence of Ta addition on the solidification microstructure, solute distribution and hardness after quenching and tempering treatments was investigated for a high-carbon high-speed steel type cast alloy (Fe1.9% C0.5% Mn4.9% Cr5.0% Mo5.07.2% V0.41.4% Ta). The compositions of Vand Ta were systematically changed to improve the distribution of hard MC carbides in the hypoeutectic range. Electron probe micro-analysis (EPMA) and X-ray diffraction (XRD) identified an oval microstructure as MC carbides containing mainly V and Ta, and a lamellar structure as M 2C carbides containing mainly Fe and Mo among the austenite (γ) dendrites. Redistribution of alloying elements during the solidification sequence of primary γ, γ + MC and M2C eutectic structure could be calculated from the Scheil-Gulliver equation and the initial composition. The macro-hardness of the quenched specimens gradually increased with increasing quenching temperature until a maximum was reached. This indicates that macro-hardness of the quenched specimens depends on both the amount and hardness of martensite matrix. All specimens which were tempered at 723873K showed secondary hardening. Furthermore, hardening of the specimens was most apparent when specimens containing large amounts of retained γ were tempered at an optimum temperature. For example, the hardness of specimens with added Ta increased to around 900HVafter tempering at 823 K. These results suggest that the macro-hardness of tempered specimens is governed by the maximum amount of carbon in the γ matrix at quenching temperature, the degree of transformation from retained γ to martensite, and the precipitation and distribution of secondary carbides.
UR - http://www.scopus.com/inward/record.url?scp=84863403525&partnerID=8YFLogxK
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U2 - 10.2320/matertrans.F-M2011836
DO - 10.2320/matertrans.F-M2011836
M3 - Article
AN - SCOPUS:84863403525
VL - 53
SP - 354
EP - 361
JO - Materials Transactions
JF - Materials Transactions
SN - 0916-1821
IS - 2
ER -