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Volume 13 (1966)
- Issue 6 Pages 263-
- Issue 5 Pages 209-
- Issue 4 Pages 157-
- Issue 3 Pages 107-
- Issue 2 Pages 47-
- Issue 1 Pages 1-
Volume 13, Issue 5
Displaying 1-6 of 6 articles from this issue
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[in Japanese]1966 Volume 13 Issue 5 Pages 209-220
Published: October 25, 1966
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSDownload PDF (781K) -
Kiyoshi Tamura, Syuzi Wanikawa, Toru Takeda1966 Volume 13 Issue 5 Pages 221-227
Published: October 25, 1966
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSImproved properties in sintered brass may be achieved through the improvement of the raw material and processing procedure.
Recently, considerable flexibility and control have been achieved in metal atomization processes and it has now become possible to obtain pre-alloyed brass powders having highly irregular particle shapes. In the present work, pressing and sintering characteristics of brass powder produced by liquid atomization were examined and further more, in order to obtain better properties as high density machine parts, effects of lubricants on the microstructure and mechanical strength of sintered specimens were discussed.View full abstractDownload PDF (2970K) -
18Ni-7Co-5Mo SteelToshihiro Kinoshita, Yoichi Tokunaga, Hiromasa Kobayashi1966 Volume 13 Issue 5 Pages 228-235
Published: October 25, 1966
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThe investigations on the characteristics of sintering and the age-hardenability of sinte red maraging steels, were carried out. Specimens were prepared from the mixed powder of Fe-18% Ni-7% Co-5% Mo and the atomized alloy powder, followed by compacting under 4-8t/cm2 and sintering or 0.5-5hrs. at 1150-1300°C in hydrogen. The results obtained are summarized as follows.
1) After air cooling from the sintering temperature, the sintered compact was relatively soft (<100HR B) with low carbon martensitic structure, which made it amenable to sizing. Subsequent age-hardening given to it for 5hrs. at 500°C, increased its hardness (>30HR c) with negligible contraction.
2) For compacts made from the mixed powder, the increase in compacting pressure and sintering temperature or in time was effective in raising the aged hardness, which might be due to the homogenization of alloying elements and the densification during sintering. Under identical conditions of compacting and sintering, the aged hardness of sintered com-pacts produced by mixing the reduced iron powder was, on the average, 2-4 HR c higher than that of electrolytic iron powder.
3) Coining and normalizing attempted in advance to age-treatment were not effective for the increase of the age-hardenability of compacts.
4) With atomized alloy powder, it was difficult to obtain the densities of more than 7.1g/c.c., even when it was repressed at 4-8t/cm2 and resintered for 1hr. at 1300°C. This may be ascribed to the relatively low aged hardness.View full abstractDownload PDF (2606K) -
Effects of Alloying ElementsToshihiro Kinoshita, Yoichi Tokunaga, Hiromasa Kobayashi1966 Volume 13 Issue 5 Pages 236-242
Published: October 25, 1966
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSThe effects of nickel, cobalt and molybdenum on the characteristics of sintering and also on the age-hardenability of sintered maraging steels were investigated. Specimens were prepared by mixing reduced iron powder with alloying element powders, and then compacted at 6t/cm2 and sintered for 1-3 hrs at 1300°C in hydrogen. Subsequently, the sintered compacts were aged for 5 hrs at 500°C. The results obtained are summarized as follows ;
1) The densification during sintering was slightly accelerated with the increase of nickel or cobalt content, but it was restrained with molybdenum content.
2) Up to a critical amount of alloying elements the aged hardness of compacts steadily increased. When these elements were added in excess, however, there was retained austenite in the martensitic structure of sintered compact, while the aged hardness decreased considerably.
It was, therefore, confirmed that the optimum base composition for the maraging steel sintered at 1300°C was of 18% nickel, 7% cobalt and 5% molybdenum.
3) Line analysis data by X-ray microanalyzer for Fe-18 Ni-7Co-5Mo compact (sintering: 1300°C× 3hrs) showed that the variations of the average concentrations were ±2% for nickel, ±3% for cobalt and ±0.5% for molybdenum.
4) The mechanical properties of sintered compacts are given in table 1, where it is observed that the sintering time and alloy composition have marked effects on mechanical strength, and that sintering at a temperature of 1300°C for the economical time of 1hr gives fairly good results.View full abstractDownload PDF (3674K) -
Hisashi Suzuki, Takaharu Yamamoto, Ichiro Kawakatsu1966 Volume 13 Issue 5 Pages 243-247
Published: October 25, 1966
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSTwo series of WC-5%TaC-10%Co alloys, using two different methods of adding of the tantalum carbide, i.e., additions in the forms of the straight TaC and of (Ta, W)C mixed carbide, were vacuum-sintered at 1375°C for 1.5hr. Studies on the effects of the adding methods and the grain size of the tantalum carbide on some properties of the alloys were carried out. Carbon contents of the alloys were minutely controlled.
The main results obtained were as follows : (1) The adding methods and the grain size of the tantalum carbide in the specimens did not affect the properties of the alloys such as the composition of the binder phase, the width and the position of three phase range, the hardness and density. Moreover, they appeared to have no relation to the inhibition-effect of tantalum carbide on the recrystallization of the WC phase. (2) The transverse-rupture strength of the alloys, however, was affected by the grain size of tantalum carbide and was greatly improved by the grain refinement. (3) In the case of addition in the from of (Ta, W)C mixed carbide, the strength of the alloys appeared to be superior to the other case, under an approximately same grain size of tantalum carbide. The reason for this superiority of the strength was not clear.View full abstractDownload PDF (5261K) -
Hisashi Suzuki, Kozi Hayashi, Ichiro Kawakatsu1966 Volume 13 Issue 5 Pages 248-253
Published: October 25, 1966
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSThe relation between the basic properties of typical WC-β-Co three phase alloys and the carbon content was already reported. In this report, the researches on the same subject have been carried out mainly on β-Co two phase alloys. The cobalt content in the alloys was mainly kept at 10wt%, and the titanium carbide content in carbides was 30%, 50% or 25%. The carbon content was strictly controlled. Samples were vacuum-sintered at 1430°C for 1 hr.
Main results obtained were as follows ;
(1) The lattice parameter of γ-phase varied with the increase of carbon content of alloys, from about 3.593Å to 3.560Å and from about 3.605Å to 3.560Å in 30% and 50% titanium carbide alloys, respectively. (2) The lattice parameter of γ-phase in 25% titanium carbide alloy (containing a small amount of WC phase) was between that of β-Co two phase alloy and that of typical WC-β-Co three phase alloy. (3) W dissolved much more than Ti.in the γ-phase in the low carbon alloys. (4) The lattice parameter of β-phase varied with the increase of carbon content of the alloys, from about 4.314Å to 4.321Å and from about 4.318Å to 4.324Å in 30%b and 50% titanium carbide alloys, respectively. (5) The change in carbon content of β-phase resulted in the extension of (β+γ) two phase range. Continued from (WC+β+γ) three phase range, the width of the range increased with the increase in the titanium carbide content. (6) Phenomena mentioned above could be explained by the Ti-W-C three phase diagram. (7) Other properties showed regular changes in the phase range.View full abstractDownload PDF (2081K)
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