Time filter

Source Type

Nakamura H.,Epson Atmix Co | Toyoshima H.,Epson Atmix Co | Otsu H.,Epson Atmix Co | Chiba A.,Tohoku University | Abe K.,Intelligent Plaza Hachinohe Inc.
Funtai Oyobi Fummatsu Yakin/Journal of the Japan Society of Powder and Powder Metallurgy | Year: 2011

Sintering of Zr pre-alloyed and water atomized 316L stainless steel powder for various content of Si was performed. The maximum sintered density was obtained at 0.8 mass% of Si for the powder pre-alloyed 0.05 mass% of Zr. Excess addition of Si -for example, 1.20 mass%- inhibited the densification by the growing of Sicontaining oxide particles. The pre-alloying of Si increased the ferrite content of powder but the correlation between the ferrite content and the level of densification was not observed. The 316L powder pre-alloyed 0.8 mass%Si and 0.05mass%Zr had finer grain size and this made a contribution to the densification by the volume diffusion.


Nakamura H.,Epson Atmix Co | Toyoshima H.,Epson Atmix Co | Otsu H.,Epson Atmix Co | Chiba A.,Tohoku University | Abe K.,Intelligent Plaza Hachinohe Inc.
Funtai Oyobi Fummatsu Yakin/Journal of the Japan Society of Powder and Powder Metallurgy | Year: 2011

2mass%Ni-Fe sintered parts are, at present, produced by premixed method using carbonyl iron powder and carbonyl nickel powder as principal raw materials. In this study, the production method of sintered parts using Zr pre-alloyed and water atomized 2mass%Ni-Fe alloy powder as raw material was investigated. Followings were observed; By pre-alloying with about 0.8 mass% of Si, Zr pre-alloyed 2mass%Ni-Fe alloy obtained the sintered density comparable to the conventional premixed method. The Si pre-alloying increased the surface energy of powder, and the activated surface diffusion, and thereby promoted formation of necks. The addition of carbon as alloying element obstructed the densification in lower sintering temperature, but, in higher temperature, promoted the densification by consuming oxygen with C-O reaction. The sintered parts of Zr and Si pre-alloyed 2mass%Ni-Fe alloy powder contained not only less pores and inclusions but also uniformly-sized grains. These resulted in higher values of tensile strength and hardness but lower elongation. By carburizing and quenching, the sintered parts of Zr and Si pre-alloyed 2mass% Ni-Fe alloy powder showed mechanical properties and hardness higher than those of the conventional premixed method. These values were controllable with adjusting of tempering temperature.


Nakamura H.,Epson Atmix Co | Sato Y.,Tohoku University | Chiba A.,Tohoku University | Murakami M.,Tokyo Medical and Dental University | And 3 more authors.
Funtai Oyobi Fummatsu Yakin/Journal of the Japan Society of Powder and Powder Metallurgy | Year: 2010

The main objective of the present work is to evaluate the effects of the addition of zirconium on the mechanical properties of Co-29Cr-6Mo sintered parts produced by metal injection molding process using water atomized powder as raw materials. The results are summarized as follows; l)The sintering density of Co-29Cr-6Mo alloy powder was increased by the addition of zirconium in both sintering atmosphere of argon and nitrogen. 2) Mechanical properties were also improved by the addition of zirconium in both sintering atmosphere of argon and nitrogen. By using MIM process, the products having better mechanical properties compared with casting method were obtained. 3) HIP treatment of sintering products increased the relative density by about 4% caused by diminishing pores. This densification produced the increase of tensile strength and 0.2% proof stress by about 100 MPa.


Nakamura H.,Epson Atmix Co | Toyoshima H.,Epson Atmix Co | Chiba A.,Tohoku University | Abe K.,Intelligent Plaza Hachinohe Inc.
Funtai Oyobi Fummatsu Yakin/Journal of the Japan Society of Powder and Powder Metallurgy | Year: 2010

The main objective of the present work is to evaluate the effects of Zr addition on various properties of SUS316L stainless steel powders produced by water-atomization of liquid metals. The results are summarized as follows; 1 ) The sintering density of SUS316L stainless steel powders pre-alloyed with 0.05 mass% of Zr was about 2 percent higher than that of the powder containing no Zr. However, in the powder pre-mixed with 0.05 mass% of Zr, no effect of Zr addition was observed. 2) Mechanical properties were improved by pre-alloying with Zr, but impaired by pre-alloying with Zr. 3) In pre-alloyed powder with 0.05 mass% of Zr, the increase of sintering density to start from 1073 K was observed. The micro-structural observation showed that the neck formation between particles started at 1073 K. The temperature is lower by about 100 K compared with the powder containing no Zr.

Loading Intelligent Plaza Hachinohe Inc. collaborators
Loading Intelligent Plaza Hachinohe Inc. collaborators