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Volume 22, Issue 6
Displaying 1-7 of 7 articles from this issue
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Yoshishige TSUMURA, Akisaku SAKAKIBARA, Katsusaburo TOYODA, Sobu HARA1972 Volume 22 Issue 6 Pages 369-376
Published: June 30, 1972
Released on J-STAGE: July 23, 2008
JOURNAL FREE ACCESSAl-Si alloys such as silumin and lautal are used for casting widely because of good castability. Metalic silicon which contains Ca as an impurity is used on alloying. Thus, some amount of Ca is believed to be present in Al-Si alloys. However, roles of Ca in Al-Si alloys have not been completely clarified yet. In this study, effects of Ca on mechanical properties (Figs. 3 and 4), castability (Figs. 58) and microstructures (Photo. 1) of silumin and lautal were investigated. The composition of the samples is shown in Table 1. The results obtained are summarized as follows:
(1) Ca showed a modification effect. Because of this effect, the presence of Ca, less than 0.05%, resulted in increase of tensile strength and elongation. However, when the amount of Ca was over 0.05%, tensile strength and elongation decreased due to formation of CaSi2. Ca hardly affected hardness.
(2) The small amount of Ca in alloys decreased fluidity and feeding ability of melts significantly.View full abstractDownload PDF (2250K) -
Study on aluminum-magnesium alloy sheets for forming use (1st report)Ken-ichiro AOKI, Mototsugu KATSUTA, Makoto SUGAMATA1972 Volume 22 Issue 6 Pages 377-385
Published: June 30, 1972
Released on J-STAGE: July 23, 2008
JOURNAL FREE ACCESSA method to eliminate stretcher-strain marking (random marking), appearing mostly in lightly strained regions, was studied in various sheets of Al-Mg alloys. Further, an aging characteristic and mechanical properties of the alloys sheets which had been subjected to the elimination method were investigated. The results obtained were as follows:
(1) Recrystallized fine grained sheets of Al-Mg alloys, which developed random marks during stretching processes, all showed yield points in stress-strain curves at tensile tests.
(2) A practical method to eliminate yielding phenomena was found. It consisted of water quenching from 350°C to 400°C.
(3) The sheets, subjected to the above treatment, did not develop significant aging.
(4) The higher the Mg content, the higher "n" values were obtained in the heat-treated sheets. The addition of Cu in the alloys inhibited grain growth. These results suggest that Al-Mg-Cu alloys with high Mg contents are suitable for forming use.View full abstractDownload PDF (1209K) -
Studies on aging phenomena of aluminum alloys (3rd report)Seiki NISHI, Takeo SHINODA1972 Volume 22 Issue 6 Pages 386-394
Published: June 30, 1972
Released on J-STAGE: July 23, 2008
JOURNAL FREE ACCESSEffects of Be and Na on aging phenomena of Al-Si-Mg-Zn alloys were investigated mainly through electrical resistivity measurement in liquid nitrogen and electron microscopy. The results obtained were as follows:
(1) Influence of Be addition on formation of G. P. zones in Al-Si-Mg-Zn alloys was investigated. Isothermal aging curves with characteristic shape and very large value of tM at 70°C were observed in Al-Si-Mg-Zn alloys. This was explained on the assumption that needle like G. P. zones absorb many vacancies at a formation period of G. P. zones. This assumption further explains retardation of formation of spherical zones at an initial aging period. However, Be was enriched in both the spherical (MgZn2) and the needle like (Mg2Si) zones and increased density of both types of zones. Overaging at high temperature aging was suppressed by Be addition.
(2) Structural changes during age hardening were investigated by means of an electron microscope. It was found that aging at 170°C for 15hrs. produced the intermediate phases of MgZn2 and Mg2Si.
(3) Na addition suppressed aging of Al-Si-Mg-Zn alloys.View full abstractDownload PDF (1297K) -
Studies on thermal fatigue of aluminum alloys (2nd report)Shuichiro WATANABE, Toshio ISOBE, Nobuhiro IGUCHI1972 Volume 22 Issue 6 Pages 395-402
Published: June 30, 1972
Released on J-STAGE: July 23, 2008
JOURNAL FREE ACCESSFailures due to thermal fatigue often occur on the pistons made of aluminum alloys, especially on those of Diesel-engines. This paper reports the thermal fatigue resistance of Al-Si casting alloys used for pistons. The resistance to thermal fatigue was evaluated by measuring the number of cycles to failure versus total amount of strain, constraint stress or plastic strain. An apparatus for thermal fatigue testing was developed, where a high frequency induction coil was employed as a heating device. The results obtained were summarized as follows:
(1) The thermal fatigue resistance of Al-Si alloy castings was in the following order:AC8B>AC8A> 15% hypersilumin> 18% hypersilumin> 23% hypersilumin. This indicates that increase in Si content lowers the resistance to thermal fatigue.
(2) The resistance to thermal fatigue was related to elongation of specimens at tensile tests. Namely, materials with higher ductility showed higher resistance.
(3) The hypoeutectic and eutectic Al-Si alloy castings failed owing to stress concentration by an necking effect produced by plastic deformation.
(4) The hypereutectic Al-Si alloy castings, especially containing more than 18%Si, failed by preferential cracking in primary Si crystals. The cracking was caused by the difference in thhe amount of thermal expansion between Si crystals and the Al matrix.View full abstractDownload PDF (1104K) -
Studies on stress corrosion cracking of Al-Zn-Mg alloys (6th report)Toshio SAITO, Takakazu TANAKA1972 Volume 22 Issue 6 Pages 403-416
Published: June 30, 1972
Released on J-STAGE: July 23, 2008
JOURNAL FREE ACCESSStress corrosion cracking tests were performed on Al-4.5wt.%Zn-2.9wt.%Mg alloy and the same alloy containing an additional element of about 0.1at.% of any one of Cu, Cr, Ti and Zr. In addition, metallurgical parameters assumed to have effects on stress corrosion cracking sensitivity of the alloys were determined.
The results obtained were summarized as follows:
(1) There were no parameters having a close relationship to stress corrosion cracking sensitivity of the alloys. Though there were great differences in metallurgical properties between the alloy containing copper and the alloy containing any one of Cr, Ti and Zr, any of these elements improved stress corrosion resistance of the alloys. These phenomena made us to suppose that the stress corrosion cracking sensitivity of the alloys would be attributed to a complicated composition of many factors.
(2)Al-4.5wt%Zn-2.9wt.%Mg alloy aged at 90°C for 30hrs. had greater toughness and some of their properties were more sensitive to corrosion circumstances as compared with the alloy subjected to two-stepped aging. The alloy containing copper had poorer toughness and its decrease of strength in a corrosive agent was greater, but its corrosion resistance was higher. The properties of the alloy containing any one of Cr, Ti and Zr were nearly inverse to those of the alloy containing copper.View full abstractDownload PDF (4613K) -
Shigeo MUROMACHI, Shigeo ZAIMA, Yuzo TAKATSUJI, Shizuo TADA, Hisakimi ...1972 Volume 22 Issue 6 Pages 417-426
Published: June 30, 1972
Released on J-STAGE: July 23, 2008
JOURNAL FREE ACCESSCopper and silicon, principal alloying elements of copper-silumin, seem to have effects on mechanical properties and machinability of the copper-silumin.
This paper describes the dry orthogonal cutting tests performed on the copper-silumin containing05.0% of copper and 4.512.0% of silicon; and effects of copper and silicon contents on chip formation, built-up edge, shearing angle, friction angle, etc. are discussed.
The results obtained were as follows:
In the alloys containing copper, the chip formation was almost equal to the flowing type with the formation of built-up edge; but in the alloys containing no copper, it was close to a tearing or shearing type and the chip thickness was extremely increased according to the plastic flow of materials. When copper content was more than 3.0%, the built-up edge and cutting resistance became relatively smaller and no differences were observed in cutting mechanism. In the alloys containing 4.5% of silicon, shearing angles were small, and the cutting efficiency was especially low when no copper was contained. However, when silicon content was 8.012.0%, no differences were observed in cutting mechanism.
The hard acicular or tabular particles of silicon, which had been ruptured by cutting action, were uniformly distributed in the built-up edge. Such a behavior of the particles would contribute to increase the hardness of built-up edges.View full abstractDownload PDF (2211K) -
Hiroyoshi TANIGUCHI, Toyohide ASANO1972 Volume 22 Issue 6 Pages 427-435
Published: June 30, 1972
Released on J-STAGE: July 23, 2008
JOURNAL FREE ACCESSDownload PDF (1988K)
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