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Volume 21, Issue 6
Displaying 1-4 of 4 articles from this issue
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[in Japanese]1974 Volume 21 Issue 6 Pages 153-160
Published: October 25, 1974
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSDownload PDF (4385K) -
Hidenori Kuroki1974 Volume 21 Issue 6 Pages 161-168
Published: October 25, 1974
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSThis investigation was undertaken to clarify the effects of pores on the mechanism of the impact fracture of sintered iron, and also on the absorbed energy. Specimens, 10×10×55 mm, were compacted from electro-lytic iron powder under the pressure of 2-9t/cm2 and sintered in hydrogen for 1 hr at 850°C. The bending load-deflection diagrams of U-notched specimens were obtained by an instrumented 30 kg⋅m-Charpy tester and by an Instron type universal testing machine.
Results were summariged as follows.
The necessary time for the impact fracture of sintered iron was too short to obtain the accurate impact load-deflection diagrams as in the case of cast iron. Therefore, the, slow bending diagrams were used for the analysis. The product of the strength and the ductility, both of which were expressed as respective functions of the density, was found to be in proportion to the slow bending energy. This fact was considered to be the reason why the notch effect-of pores on the impact value was stronger than those on the ultimate tensile strength and on the tensile elongation.View full abstractDownload PDF (2779K) -
Takashi Daikoku, Fujimitsu Masuyama, Katsuaki Uehara, Kazuo Hiromatsu1974 Volume 21 Issue 6 Pages 169-176
Published: October 25, 1974
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSA liquid phase sintering method was carried out in order to sinter the 13Cr-Mo-Ti steel strengthened by y-A1203 with Fe-Ti alloy powders, and the reaction of dispersoid with the alloy elements and its effect on the structure obtained were investigated.
The results obtained are as follows:
1) γ-Al2O3 added as the dispersoid has reacted with Ti existing in the Fe-Ti alloy and the matrix. As a results of this reaction, a complex oxide has been produced and the distribution of oxide particles improved.
2) Dispersion strengthening effect is also improved by satisfactory thermal stability of the complex oxide produced by above mentioned reaction and also better dispersoid/matrix bondings are obtained.View full abstractDownload PDF (6108K) -
Akira Okamoto, Kenro Kitamura, Tetsuro Yoshida1974 Volume 21 Issue 6 Pages 177-182
Published: October 25, 1974
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSCopper-ferrous ferrites were sintered under various conditions to elucidate the mechanism of discontinuous grain growth.
Straight grain boundaries were observed in the discontinuously growing grains. This boundary was determined to be the (111) plane of growing grain. Dynamical consideration of the straight boundaries suggested the existence of a liquid phase. The existence of the liquid phase, which produces the straight boundaries and gives a large mobility to them, is considered to be the main cause of discontinuous grain growth.
A possible new mechanism was proposed for the nucleation in the discontinuous grain growth. Final size of a giant grain produced by discontinuous grain growth was controlled by the initial grain size, firing temperature and oxygen content of samples.View full abstractDownload PDF (4020K)
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