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Volume 32, Issue 5
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[in Japanese]1985 Volume 32 Issue 5 Pages 173-183
Published: July 25, 1985
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSDownload PDF (4396K) -
Kanji Notomi, Seiya Furuta, Nobuyasu Kawai1985 Volume 32 Issue 5 Pages 184-189
Published: July 25, 1985
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSFive compositions of high carbon adamite steel powders (1.8%C, 2.2%C, 2.6%C, 2.9%C, and 3.7%C+1. 2%Ni+1.2%Cr+0.3%Mo) were produced by gas-atomization, and their fully densified P/M steel billets were made by hot isostatic pressing. Microstructures and mechanical properties of the P/M steels were investigated in comparison with the conventional adamite steel (1.7%C+l.2%Ni+l.2%Cr+0.3%Mo).
In the P/M steels, fine carbides are uniformly distributed, whereas in the conventional steel, large-sized carbides are distributed among fine carbides.
Mechanical properties of the P/M steels are as follows: The wear property of the P/M steels is improved with the increase of carbon content. On the contrary, the bend strength and fire cracking properties are decreased with increasing carbon content. But, these properties of the 2.5%C adamite P/M steel are found to be superior or equivalent to those of the conventional steel.View full abstractDownload PDF (5864K) -
Hideshi Miura, Masazumi Hanada, Youichi Tokunaga1985 Volume 32 Issue 5 Pages 190-195
Published: July 25, 1985
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThe authors have previously investigated the sintering process and spheroidization of the pores of iron and ferrophosphorus mixed powder compacts. In this paper, the tensile and impact properties of Fe-P and Fe-P-C are investigated, and the correlation between the spherical pore and the properties is discussed.
Addition of finer ferrophosphorus powder improves the tensile properties; particularly ductility increases with sintering above eutectic temperature (1050°C) as a result of appearance of small and spherical pores. On the other hand, the ductile-brittle transition curve appears more evidently with the ferrophosphorus additions, and the transition temperature increases with increase of phosphorus content. Though favourable combinations of strength and ductility can be attained with Fe-0.4 wt%P, the limiting concentration of phosphorus is 0.3 wt% in view of practical toughness. Addition of graphite to iron compacts containing low phosphorus content increases the strength, while it causes a drop of both ductility and toughness. However, the addition of graphite to that of high phosphorus content above 0.4 wt% improves somewhat the toughness as a result of grain refinement.View full abstractDownload PDF (4234K) -
Hisashi Suzuki, Hideaki Matsubara, Akira Matsuo1985 Volume 32 Issue 5 Pages 196-199
Published: July 25, 1985
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThe hardness, transverse-rupture strength (TRS), deformability, etc. of TiC0.7N0.3-and TiC0.5N0.5-MPo alloys vacuum-sintered and then HIP-treated were studied mainly in the temperature range from 1073 K to 1273 K, comparing with those of Ti(C, N)-Mo2C-Ni alloys.
The decrease in the hardness and TRS of Mo bonded alloys with increasing test temperature was markedly suppressed. The alloys containing 20-40 vo1%Mo showed at 1273 K the values of hardness and TRS as high as 600-800 Hv and 0.9-1.2 GPa, respectively, with a extremely high resistance to deformation. Therefore, the Mo bonded alloys were considered to be of importance for the special tool materials, when coated with the layer having high resistance to oxidation.View full abstractDownload PDF (4094K) -
Koji Hayashi, Yoshihiro Onomura1985 Volume 32 Issue 5 Pages 200-204
Published: July 25, 1985
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThe effects of N2 pressure (0.1-50 MPa) during sintering on the thickness of the microstructural heterogeneous layer (MHL) formed near the surface of the compact, transverse-rupture strength, etc., were investigated for Si3N4-(10-20) mo1%MgO-5.5 mo1%Al2O3 ceramics. The sintering temperature and time were 1973 K and 3.6 ks, respectively. The N2 gas was introduced into the furnace at about 1273 K.
When the compacts were sintered under a definite N2 pressure, for example, about 20 and 7 MPa for 10 and 15 mo1%MgO, respectively, the evolutions of N and Si were suppressed, the thickness of MHL became very small and at the same time the strength of the surface layer of the compact (which was normally less than that of the inside in the case of 0.1 MPa) became nearly the same value as that of the inside. At the higher pressure, the strength of both surface layer and the inside decreased considerably. Some discussion was made on these results.View full abstractDownload PDF (3278K) -
Hisashi Suzuki, Hideaki Matsubara, Akira Matsuo, Kunio Shibuki1985 Volume 32 Issue 5 Pages 205-209
Published: July 25, 1985
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThe titanium carbonitrides, Ti(C, N), with different C/N ratios were coated on HIP-treated WC-Co substrates by PVD process at 773 K. The transverse-rupture strength of coated specimens and the properties such as hardness and resistance to oxidation of coated layer were studied in relation to C/N ratios.
The hardness of coated layer decreased with decreasing C/N ratio. The strength of coated specimens was not almost affected by C/N ratios. The abrupt decrease in the strength was observed, when the specimens were annealed at temperature of about 1173 K. This showed that each layer was lacking in the thermal stability. It was found that the resistance to oxidation of the layer varied according to C/N ratios, and it became worst at C/N ratio of 2/8. A further study on this subject, however, is needed.View full abstractDownload PDF (4521K)
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