Yoneda Advanced Casting Co.

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Yoneda Advanced Casting Co.

Japan
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Ueda K.,Tohoku University | Nakaie K.,Tohoku University | Namba S.,Kobe Steel | Yoneda T.,Yoneda Advanced Casting Co. | And 2 more authors.
Materials Transactions | Year: 2013

Pin-on-disk wear tests using biomedical Co-Cr-Mo alloy pins and alumina disks were conducted in Kokubo and 1% lactic acid solutions. The mass loss and elution of metallic ions were measured and the surface of the pin was observed after the wear test. Mass loss of the alloy pins in 1% lactic acid solution was 10 times higher than the mass loss in Kokubo solution. In Kokubo solution, the as-cast pins exhibited higher mass loss and higher total amount of eluted ions than solution-treated pins. The Cr and Mn ion content in Kokubo solution was lower than expected, based on the chemical composition of the alloy. The incorporation of Cr and Mn ions into the calcium phosphate detected on the wear track of disks is the possible reason for the small amount of these ions in Kokubo solution. © 2013 The Japan Institute of Metals and Materials.


Kakiuchi S.,Toyama Industrial Technology Center | Tomida S.,Toyama Industrial Technology Center | Yamagishi H.,Toyama Industrial Technology Center | Yoneda T.,Yoneda Advanced Casting Co. | Nakata K.,Osaka University
Yosetsu Gakkai Ronbunshu/Quarterly Journal of the Japan Welding Society | Year: 2013

The cause of hot cracking in Co-Cr-Mo (CCM) alloy induced by surface melting by electron beam (EB) irradiation was investigated for different EB currents. A regular pattern of linear grooves and ridges was formed by horizontal EB scanning with a square raster pattern. However, some irregular-shaped grooves also occurred. As the EB current was increased, these irregular grooves became larger and cracks appeared within them. Cross-sectional observations showed that the cracks occurred mainly in the heat-affected zone (HAZ) along grain boundaries and extended into the fused zone (FZ). The HAZ cracks terminated at grain boundary precipitates. The fractured surface of the cracks exhibited well-developed cellular-dendritic solidification structures in the FZ, indicating that these were solidification cracks. In contrast, the cracks in the HAZ had an immature dendritic structure with a relatively flat surface, typical of liquation cracks. It can be deduced that the cracks were caused by a liquid film remaining at the grain boundaries, and the driving force for crack propagation was shrinkage distortion caused by the fusion-solidification process.


Alfirano,Tohoku University | Mineta S.,Tohoku University | Namba S.,Kobe Steel | Yoneda T.,Yoneda Advanced Casting Co. | And 2 more authors.
Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science | Year: 2012

The microstructures of biomedical ASTM F 75/F 799 Co-28Cr-6Mo-0.25C-0.175N- (0 to 1)Si-(0 to 1)Mo alloys (mass pct) were investigated before and after heat treatment, with special attention paid to the effect of nitrogen on the phases and the dissolution of precipitates. The heat treatment temperatures and holding periods employed ranged from 1448 to 1548 K (1175 to 1275 °C) and 0 to 43.2 ks, respectively. A blocky-dense π-phase precipitate and a lamellar cellular colony, which consisted of an M 2X type precipitate and a Γ phase, were mainly detected in the as-cast alloys with and without added Si, respectively. The addition of nitrogen caused cellular precipitation, while the addition of Si suppressed it and enhanced the formation of the π phase. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) analyses suggested that a discontinuous reaction, i.e., Γ1 → Γ2 + M 2X, might be a possible formation mechanism for the lamellar cellular colony. Nitrogen was enriched in the M 2X type, η-phase, and π-phase precipitates, but was excluded from the M 23X 6 type precipitate. Complete precipitate dissolution was observed in all of the alloys under varied heat treatment conditions depending on the alloy composition. The addition of nitrogen decreased the time required for complete precipitate dissolution at low heat-treatment temperatures. At high temperatures, i.e., 1548 K (1275 °C), complete precipitate dissolution was delayed by the partial melting that accompanied the formation of the precipitates such as the π phase resulting in the boundary between the complete and incomplete precipitate dissolution regions in having a C-curved shape. © The Minerals, Metals & Materials Society and ASM International 2012.


Mineta S.,Tohoku University | Namba S.,Kobe Steel | Yoneda T.,Yoneda Advanced Casting Co. | Ueda K.,Tohoku University | Narushima T.,Tohoku University
Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science | Year: 2010

The microstructures of as-cast and heat-treated biomedical Co-Cr-Mo (ASTM F75) alloys with four different carbon contents were investigated. The as-cast alloys were solution treated at 1473 to 1548 K for 0 to 43.2 ks. The precipitates in the matrix were electrolytically extracted from the as-cast and heat-treated alloys. An M23C6 type carbide and an intermetallic r phase (Co(Cr,Mo)) were detected as precipitates in the as-cast Co-28Cr-6Mo-0.12C alloy; an M23C6 type carbide, a r phase, an g phase (M6C-M12C type carbide), and a p phase (M2T3X type carbide with a b-manganese structure) were detected in the as-cast Co-28Cr-6Mo-0.15C alloy; and anM23C6 type carbide and an g phase were detected in the as-cast Co-28Cr-6Mo-0.25C and Co-28Cr-6Mo-0.35C alloys. After solution treatment, complete precipitate dissolution occurred in all four alloys. Under incomplete precipitate dissolution conditions, the phase and shape of precipitates depended on the heat-treatment conditions and the carbon content in the alloys. The p phase was detected in the alloys with carbon contents of 0.15, 0.25, and 0.35 mass pct after heat treatment at high temperature such as 1548 K for a short holding time of less than 1.8 ks. The presence of the p phase in the Co-Cr-Mo alloys has been revealed in this study for the first time. © The Minerals, Metals & Materials Society and ASM International 2010.


Mineta S.,Tohoku University | Alfirano,Tohoku University | Namba S.,Kobe Steel | Yoneda T.,Yoneda Advanced Casting Co. | And 2 more authors.
Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science | Year: 2012

The phase and formation/dissolution of biomedical Co-28Cr-6Mo-xC (x = 0, 0.12, 0.16, 0.24, 0.33, and 0.41, in mass pct) alloys were investigated before and after heat treatment at high temperatures. The heat-treatment temperatures and holding periods were varied from 1473 K to 1623 K (1200 C to 1350 C) and from 0 ks to 43.2 ks, respectively. The intermetallic r phase was observed in the as-cast and heat-treated alloys without added carbon. In the carbon-added alloys, the M23C6-type, p-phase (M2T3X-type carbide with a b-Mn structure), g-phase (M6CM12C-type), and M7C3-type carbides were observed depending on the carbon content and heattreatment conditions. A complete precipitate dissolution was achieved in the alloys with a carbon content of 0 to 0.24 mass pct. The holding time required for complete precipitate dissolution in the carbon-added alloys increased with increasing heat-treatment temperature above 1548 K (1275 C). The formation of p-phase and M7C3-type carbides was observed in the carbon-added alloys during heat treatment at high temperatures of 1548 K to 1623 K (1275 C to 1350 C). Two types of p phase with different lattice constants and chemical compositions were confirmed in the alloys with carbon contents of 0.24, 0.33, and 0.41 mass pct after heat treatment at 1573 K to 1623 K (1300 C to 1350 C). The M7C3-type carbide observed at high temperatures occurred in a starlike precipitate with a complicated microstructure. © The Minerals, Metals & Materials Society and ASM International 2012.


Mineta S.,Tohoku University | Namba S.,Kobe Steel | Yoneda T.,Yoneda Advanced Casting Co. | Ueda K.,Tohoku University | Narushima T.,Tohoku University
Advanced Materials Research | Year: 2010

Microstructural changes occurring in biomedical Co-Cr-Mo alloys with three carbon levels due to solution treatment and aging were investigated. Ingots of Co-Cr-Mo alloys with three different carbon levels were prepared by vacuum furnace melting; their chemical composition was Co-28Cr-6Mo-xC (x = 0.12, 0.25 and 0.35 mass%). Precipitates were electrolytically extracted from as-cast and heat-treated alloys. An M23C6 type carbide and a σ s phase were detected as precipitates in as-cast Co-28Cr-6Mo-0.12C alloy, and an M23C6 type carbide and an η phase (M 6C-M12C type carbide) were detected in as-cast Co-28Cr-6Mo-0.25C and Co-28Cr-6Mo-0.35C alloys. Only the M23C 6 type carbide was detected during solution treatment. Complete precipitate dissolution occurred in all the three alloys after solution treatment. The holding time required for complete precipitate dissolution increased with increasing carbon content and decreasing solution treatment temperature. Complete precipitate dissolution occurred in the Co-Cr-Mo-C alloys solution treated at 1523 K for 43.2 ks; they were then subjected to aging from 873 to 1473 K for a heating time up to 44.1 ks after complete precipitate dissolution in solution treatment at 1523 K for 43.2 ks. The M 23C6 type carbide with a grain size of 0.1-3 μm was observed after aging. A time-temperature-precipitation diagram of the M 23C6 type carbide formed in the Co-28Cr-6Mo-0.25C alloy was plotted. © (2010) Trans Tech Publications.


Narushima T.,Tohoku University | Alfirano,Tohoku University | Mineta S.,Tohoku University | Namba S.,Kobe Steel | And 2 more authors.
Advanced Materials Research | Year: 2011

The phase and dissolution behavior of precipitates in biomedical ASTM F75 Co-Cr-Mo-C-Si-Mn alloys were investigated. Alloys of five different compositions, Co-28Cr-6Mo-0.25C-1Si, Co-28Cr-6Mo-0.25C-1Mn, Co-28Cr-6Mo-0.25C- 1Si-1Mn, Co-28Cr-6Mo-0.15C-1Si, and Co-28Cr-6Mo-0.35C-1Si, were heat-treated from 1448 to 1548 K. The precipitates observed in the as-cast and heat-treated alloys were carbides (M23C6 type, η-phase, and π-phase) and an intermetallic compound (χ-phase). The main precipitates observed after heat treatment at high temperatures such as 1548 K were π-phase and M23C6 type carbide. At these high temperatures, two types of starlike precipitates-dense and stripe-patterned-were observed. The starlike-dense precipitate was the π-phase, and the starlike precipitate with a stripe pattern was identified as the M23C 6 type carbide and metallic fcc γ-phase. In the alloys heat-treated at 1448 to 1498 K, blocky-dense M23C6 type carbide was primarily observed. χ-phase was detected in the Co-28Cr-6Mo-0.15C-1Si alloy under as-cast condition and after heat treatment at 1448-1523 K for a short holding time. The addition of Si seemed to increase the holding time for complete precipitate dissolution because of the effects of Si on the promotion of π-phase formation at high temperatures and the increased carbon activity in the metallic matrix. © (2011) Trans Tech Publications, Switzerland.


Mineta S.,Tohoku University | Alfirano,Tohoku University | Namba S.,Kobe Steel | Yoneda T.,Yoneda Advanced Casting Co. | And 2 more authors.
Materials Science Forum | Year: 2010

The phase and morphology of precipitates in heat-treated Co-28Cr-6Mo-xC (x = 0.12, 0.15, 0.25, and 0.35mass%) alloys were investigated. The as-cast alloys were solution-treated in the temperature range of 1473 to 1623 K for 0 to 43.2 ks. Complete precipitate dissolution was observed in all four alloys, each of which had different carbon contents. The holding time for complete dissolution was greater for alloys with greater carbon content. The curve representing the boundary between the complete- and incomplete-dissolution conditions for each alloy is C shaped. Under the incomplete precipitate dissolution conditions of the Co-28Cr-6Mo-0.25C alloy, an M23C6 type carbide and a π-phase (M2T3X type carbide with β-Mn structure) were observed at 1548 to 1623 K, and starlike precipitates with a stripe pattern and with a dense appearance were both observed; the former comprised the M 23C6 type carbide + γ-phase, and the latter was the π-phase. In contrast, only a blocky-dense M23C6 type carbide was observed at 1473 to 1523 K. © (2010) Trans Tech Publications.


Mineta S.,Tohoku University | Alfirano,Tohoku University | Namba S.,Kobe Steel | Yoneda T.,Yoneda Advanced Casting Co. | And 2 more authors.
Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science | Year: 2013

The precipitates in as-cast and heat-treated biomedical Co-28Cr-6Mo-(0 to 0.35)C-(0.15 to 0.25)N alloys (mass pct) were investigated. Heat treatment was carried out at temperatures of 1473 K to 1573 K (1200 C to 1300 C) for holding periods of 0 to 43.2 ks. In the as-cast and heat-treated Co-Cr-Mo-N alloys, no precipitates were detected; nitrogen effectively inhibited the formation of the σ-phase and stabilized the face-centered cubic (fcc) metallic γ-phase. The precipitates observed in the as-cast and heat-treated Co-Cr-Mo-C-N alloys were of the M23X6 type, M2X type, π-phase (M2T3X type with a β-Mn structure), and η-phase (M6X-M12X type). Complete precipitate dissolution was detected in the alloys with carbon contents of less than 0.3 mass pct regardless of the nitrogen content. The main precipitates were of the M2X and M23X6 types after heat treatment for 1.8 to 43.2 ks. The π-phase precipitate was detected in the early stage of heat treatment at high temperatures. The formation of the M2X-type precipitate was enhanced by the addition of nitrogen, although the constitution of the precipitates depended on the balance between the nitrogen and carbon contents and the heat-treatment conditions. © 2012 The Minerals, Metals & Materials Society and ASM International.


Alfirano,Tohoku University | Mineta S.,Tohoku University | Namba S.,Kobe Steel | Yoneda T.,Yoneda Advanced Casting Co. | And 2 more authors.
Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science | Year: 2011

The effect of the addition of Si or Mn to ASTM F75 Co-28Cr-6Mo-0.25C alloys on precipitate formation as well as dissolution during solution treatment was investigated. Three alloys-Co-28Cr-6Mo-0.25C-1Si (1Si), Co-28Cr-6Mo-0.25C-1Mn (1Mn), and Co-28Cr-6Mo-0.25C-1Si-1Mn (1Si1Mn)-were heat treated from 1448 K to 1548 K (1175 °C to 1275 °C) for a holding time of up to 43.2 ks. In the case of the as-cast 1Si and 1Si1Mn alloys, the precipitates were M 23C6-type carbide, η phase (M6C-M 12C-type carbide), and π phase (M2T3X-type carbide with a β-Mn structure), while in the case of the as-cast 1Mn alloy, M23C6-type carbide and η phase were detected. The 1Si and 1Si1Mn alloys required longer heat-treatment times for complete precipitate dissolution than did the 1Mn alloys. During the solution treatment, blocky dense M23C6-type carbide was observed in all the alloys over the temperature range of 1448 K to 1498 K (1175 °C to 1225 °C). At the heat-treatment temperature of 1523 K (1250 °C), starlike precipitates with stripe patterns-comprising M23C6-type carbide and metallic face-centered-cubic (fcc) γ phase-were detected in the 1Si and 1Si1Mn alloys. A π phase was observed in the 1Si and 1Si1Mn alloys heat treated at 1523 K and 1548 K (1250 °C and 1275 °C) and in the 1Mn alloy heat treated at 1548 K (1275 °C); its morphology was starlike-dense. The addition of Si appeared to promote the formation of the π phase in Co-28Cr-6Mo-0.25C alloys at 1523 K and 1548 K (1250 °C and 1275 °C). Thus, the addition of Si and Mn affects the phase and morphology of the carbide precipitates in biomedical Co-Cr-Mo alloys. © 2011 The Minerals, Metals & Materials Society and ASM International.

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