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Volume 48 (1977)
- Issue 4 Pages 251-
- Issue 3 Pages 179-
- Issue 2 Pages 107-
- Issue 1 Pages 4-
Volume 48, Issue 2
Displaying 1-10 of 10 articles from this issue
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Hiroyasu Mitani, Kazuhiko Majima1977 Volume 48 Issue 2 Pages 107-118
Published: April 15, 1977
Released on J-STAGE: May 25, 2009
JOURNAL FREE ACCESSThe sintering process of Fe-C binary mixed powder compacts and Fe-Cu-C ternary mixed powder compacts was studied mainly from the viewpoint of phase transformation and diffusion.
The results obtained were as follows:
(1) After the α→γ transformation during heating in vacuum of 10-5mmHg for the Fe-C binary mixed powder compacts, the expansion was observed, the amount of which was nearly in proportion to the amount of additional graphite, and the expansion curve in dilatation and the combined carbon concentration curve well agreed. This means that the carburization was done mainly by the carbon diffusion through the contacting surface of graphite and iron powder rather than through the medium CH4 or CO gas.
(2) From the vacuum measurement, it was apparent that the amount of gas discharge from the specimen with the reduced iron powder was by far larger than that from the other specimens. On the contrary, its dilatational expansion was minimum, indicating that the specimen was not swelled by the gas pressure.
(3) It was clarified from the thermal analysis that the elimination of the abnormal expansion observed during sintering process of Fe-Cu binary mixed powder compacts was carried out by the liquid phase sintering related to the ternary monotecto-eutectic reaction at 1095°C.
(4) The extremely rapid critical cooling rate of 1100°C/sec. was obtained from the Fe-1.0%C binary sintered compacts, while it became 360°C/sec. for the Fe-2.0%Cu-C ternary sintered compacts, and 140°C/sec. for the Fe-6.5%Cu-1.0%C ternary sintered compacts.View full abstractDownload PDF (661K) -
Yoshiaki Takeya, Tadao Hayasaka1977 Volume 48 Issue 2 Pages 119-121
Published: April 15, 1977
Released on J-STAGE: May 25, 2009
JOURNAL FREE ACCESSAn investigation was made about mechanical properties of 3 kind's sintered stainless steel of SUS410L, 316L and 304L after sintering in vacuum and in reducing atmosphere.
As the result, it was observed that the elongation of those sintered in reducing atmosphere is smaller than those sintered in vacuum.
Hereunder have been described about some product examples to which the results are practically applied.View full abstractDownload PDF (3412K) -
Kenya Motoyoshi, Naoki Motooka1977 Volume 48 Issue 2 Pages 122-127
Published: April 15, 1977
Released on J-STAGE: May 25, 2009
JOURNAL FREE ACCESSStainless steel has attractive properties such as high corrosion and heat resistance. But its machinability is inferior to that of conventional steel. The final cost of structural parts can be reduced in the case of P/M stainless steel made from atomized alloy powder because machining is unnecessary.
This paper deals with the mechanial properties, corrosion and heat resistance as well as its applications of sintered stainless steel parts.View full abstractDownload PDF (2057K) -
Kunio Ohara, Rokuro Satô1977 Volume 48 Issue 2 Pages 128-131
Published: April 15, 1977
Released on J-STAGE: May 25, 2009
JOURNAL FREE ACCESSTypical stainless steels were made by the powder forging process, using, as starting materials, commercial water atomized powders with compositions corresponding to SUS 316L, 410L and 430L.
Their tensile properties and impact values were measured and compared with those of JIS for wrought materials.
To obtain forged products with 99% density ratio, the forging pressure more than 8ton/cm2 was necessary in the case of 410L and 430L, whereas in the case of 316L the pressure more than 14ton/cm2 was necessary.
Tensile properties of forged products with 99% density ratio were almost equivalent to those indicated by JIS.
However, their U-notched Charpy values were much lower than those of JIS, because of their surface defects induced by the preferential oxidation of chromium during the heating prior to the forging.View full abstractDownload PDF (4588K) -
Tetsuo Katô, Katsushi Kusaka, Tatsuo Hisada1977 Volume 48 Issue 2 Pages 132-136
Published: April 15, 1977
Released on J-STAGE: May 25, 2009
JOURNAL FREE ACCESSAs to water-atomized ferritic stainless steel powders containing 12/23% Cr and Mo less than 2%, the influence of Cr and Mo compositions on the corrosion resistance of the sintered steels was studied.
Results were summarized as follows.
(1) In 5% NaCl solution spray, sintered steels containing Cr more than 18% were almost free of rusting after 8hrs. The effect of Mo alloying on this test was not observed.
(2) The corrosion resistance of sintered steels in 5% H2SO4 solution was remarkably improved by Mo alloying. The corrosion rate of 18% Cr sintered steels containing 1% and 2% Mo was 1/5 and 1/10 respectively to the sintered steels without Mo.
(3) If the sulfuric corrosion rate of 18% Cr and 18% Cr-2% Mo sintered steels was compared with the annealed cast steel, logarithm of the corrosion rate of 18% Cr-2% Mo could be expressed as a linear equation of the sintered density, while in the case of 18% Cr the rate of fully dense sintered steel is bigger than that of annealed cast steel.
(4) In this solution, the dropping of powder particle from the surface of 18% Cr sintered steel was observed, while this phenomenon was not observed in 18% Cr-2% Mo sintered steel.
Therefore, Mo alloying remarkably improves the corrosion resistance of sintered ferritic stainless steels.View full abstractDownload PDF (6593K) -
Tetsuo Katô, Katsushi Kusaka1977 Volume 48 Issue 2 Pages 137-143
Published: April 15, 1977
Released on J-STAGE: May 25, 2009
JOURNAL FREE ACCESSThe mechanical properties of sintered ferritic stainless steels were studied powdermetallurgically.
The results were summarized as follows:
(1) The tensile strength got higher with an increase of Cr wholly, while the resultant ductility was better for 18% or less of Cr because of good sinterability.
(2) The tensile strength got higher, without loss of ductility in 2% or less of Si and Mo addition to 12∼18% Cr-regions.
(3) The porosity-sensitive toughness was appreciably improved at higher sintering temperature due to spherodization of residual pores.
(4) External notch (Kt∼4) in tensile test gave the loss of 20% or less to original tensile strength almost independent of porosity.View full abstractDownload PDF (2185K) -
Tetsuo Katô, Katsushi Kusaka, Toshihiro Katô1977 Volume 48 Issue 2 Pages 144-150
Published: April 15, 1977
Released on J-STAGE: May 25, 2009
JOURNAL FREE ACCESSFrom the point of view of the powder metallurgy a study was made about magnetic properties of sintered materials of water-atomized iron-chromium alloy powder containing 14 up to 26% chromium.
The results obtained can be summarized as per written hereunder:
(1) Sintered 16% Cr-Fe alloys have the highest mangetic properties. If they are sintered at 1200°C for 2hrs in vacuo, the maximum permeability becomes 3500 and coercive force 1.26Oe respectively. They are almost equal to the properties of bulk magnetic stainless steel.
(2) Magnetic properties of sintered materials depend upon pores' shape and size distribution. In case that the porosity is constant the rounder, the bigger of the pores and the higher of the magnetic properties.
(3) Since pores are being dispersed in the sintered materials, the eddy current is found to be restrained and watt loss is very few in alternating magnetic fields.View full abstractDownload PDF (4288K) -
Takeshi Anbo, Takahiro Motone, Takashi Furuya, Kôichi Sasaki1977 Volume 48 Issue 2 Pages 151-159
Published: April 15, 1977
Released on J-STAGE: May 25, 2009
JOURNAL FREE ACCESSRecently high coercivity ferrite magnets have been demanded for stators or rotors of motors and generators.
We took up the anisotropic strontium ferrite magnets pressed in wet for above request and studies the influence of the addition of some oxides such as SiO2, K2O, Li2O, MgO, BaO and Bi2O3 on the magnetic properties.
Addition of SiO2 delays the sintering reaction and decreases the degree of orientation at each sintering temperature below 1300°C.
Remanence Br and maximum energy product (BH)max decrease slightly with increase of SiO2, but coercive force BHC rises excellently. For instance, at 0.25∼0.6wt% SiO2, BHC more than 3, 000Oe was obtained with Br 3, 900∼4, 000G and (BH)max 3.3∼3.7 MGOe.
Duplex addition of SiO2 and K2O increases BHC and duplex addition of SiO2 and BaO increases Br and (BH)max respectively.View full abstractDownload PDF (5012K) -
Tohru Takeda1977 Volume 48 Issue 2 Pages 160-167
Published: April 15, 1977
Released on J-STAGE: May 25, 2009
JOURNAL FREE ACCESSIn order to clarify some problems of the production of sintered stainless steels, atomizing parameters of molten steels are reviewed in terms of their influence on powder properties, and ultimate structural control. And also the effect of powder characteristics on the production of sintred high density stainless steel is discussed briefly.View full abstractDownload PDF (6605K) -
Yoshikazu Takai, Hiroo Inamori, Yoshio Katô1977 Volume 48 Issue 2 Pages 168-174
Published: April 15, 1977
Released on J-STAGE: May 25, 2009
JOURNAL FREE ACCESSAt Hoshizaki Plant of Daido Steel Co., Ltd. there was completed a replacing construction of the second intermediate and finishing train of wire rod mill with the block mill of 10 stands made by MOELLER UND NEUMANN GMBH (West Germany) at the end of August in 1976 and an industrial operation started from October in the same year.
This mill produces those special steels such as structural carbon steel and alloy steel, spring steel, bearing steel, free-machining steel, alloy tool steel, stainless steel, heat resistance steel etc. with the finishing rolling speed of 50m/sec.View full abstractDownload PDF (6687K)
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