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Volume 28, Issue 8
Displaying 1-8 of 8 articles from this issue
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Youtaro MURAKAMI1978 Volume 28 Issue 8 Pages 375-376
Published: August 30, 1978
Released on J-STAGE: July 23, 2008
JOURNAL FREE ACCESSDownload PDF (356K) -
Yoshiro KOMIYAMA, Kunihiko UCHIDA, Masahiro GUNSHI1978 Volume 28 Issue 8 Pages 377-382
Published: August 30, 1978
Released on J-STAGE: July 23, 2008
JOURNAL FREE ACCESSAn aluminum alloy for automotive pistons containing Mn as a substitute for Ni has been successfully developed in the past ten years. The alloy consists of Cu3%, Si9.5%, Mg0.6%, Mn 0.4 to 0.8% and Al. The alloy ensures cost saving and improved durability of pistons. Mn in the alloy forms a compound with Fe, but not with Cu. Mn 0.4 to 0.8% leads to favorable properties of pistons. The alloy containing Mg 0.4 to 0.6% has the maximum tensile strength at room temperature, and that containing 0.6 to 0.8% at elevated temperatures. Mg more than 0.8% decreases the tensile strength.View full abstractDownload PDF (1031K) -
Yoshiro KOMIYAMA, Kunihiko UCHIDA, Masahiro GUNSHI1978 Volume 28 Issue 8 Pages 383-387
Published: August 30, 1978
Released on J-STAGE: July 23, 2008
JOURNAL FREE ACCESSThe fatigue strength, creep resistance, coefficient of thermal expansion, dimensional change in heat cycle and charpy impact strength of a Ni-free alloy newly developed for automotive pistons were measured. Those of conventional piston alloys were also presented. Superity of this Ni-free alloy is confirmed.View full abstractDownload PDF (539K) -
Hiroaki YOKOBAYASHI, Tadashi CHIBA, Junichiro MOROOKA1978 Volume 28 Issue 8 Pages 388-396
Published: August 30, 1978
Released on J-STAGE: July 23, 2008
JOURNAL FREE ACCESSThe strength of a conventional hollow stem restricts the maximum circumscribed circle of an extrusion resulting in difficulty in multi-holes indirect extrusion. Development of a filler block was the first step toward the solution of this problem. A multi-holes die has been developed through calculations and practical operations in which the metal follow occurs only in the vicinity of die for indirect extrusion. This was achieved by reducing the pressurized area and extending the area of extrusion path using a filler block having high buckling strength and machinability. Such a development ensures further productivity, cost reduction of dies, and more stability in dimensional accuracy and increasing the yield of extrusion than in the direct extrusion.View full abstractDownload PDF (2892K) -
Hiroaki YOKOBAYASHI, Tadashi CHIBA, Junichiro MOROOKA1978 Volume 28 Issue 8 Pages 397-405
Published: August 30, 1978
Released on J-STAGE: July 23, 2008
JOURNAL FREE ACCESSIn practical operations of a 1800 US tons indirect extrusion press in which multiholes extrusion is possible using a shaved billet, the productivity is advanced by two times in such ways as development of an automatic ring picker to shorten idle time and to achieve continuous operation, minimizing the temperature deviation in a long and heavy sectioned billet, and setting up an area ray out.View full abstractDownload PDF (1323K) -
Mutsuo OHTA, Teruto KANADANI, Masuo YAMADA, Akira SAKAKIBARA1978 Volume 28 Issue 8 Pages 406-412
Published: August 30, 1978
Released on J-STAGE: July 23, 2008
JOURNAL FREE ACCESSIt is confirmed by measuring electrical resistivity of the low-concentrated Al-Ag alloys to form G. P. zones at relatively high temperatures in the nucleation-and-growth mechanism. Increase of as-quenched resistivity ρ0 due to the concentration fluctuation at the quenching temperature is found when quenched at lower temperatures. Aging behaviors in the alloys having remarkable fluctuation variously change with the vacancy concentration. These behaviors are interpreted in terms of the difference in the growth rate of G. P. zones nucleated in the region of higher and lower solute concentration induced by the fluctuation and in terms of the changes of this difference with vacancy concentration. G. P. zones may be formed in the alloys by the spinodal decomposition at first with indefinite surface, grown to be larger ones with definite surface, and changed to be ordered η-zones.View full abstractDownload PDF (937K) -
Hisashi SUZUKI, Koji HAYASHI1978 Volume 28 Issue 8 Pages 413-417
Published: August 30, 1978
Released on J-STAGE: July 23, 2008
JOURNAL FREE ACCESSThe effect of thermomechanical treatment (TMT) on the fatigue strength of Al-4%Cu alloy was studied in relation to the changes in aging and crystal grain structures by TMT. The TMT was done in the combination of aging at 150°C and repetition of cold-rolling with 2060% reductions. The fatigue strength of thermomechanically treated alloy sharply improves when the density of θ' coexisting with θ" is considerably increased leading to the highly age-hardened state and to the formation of wavy slip bands during fatigue processes, and at the same time when the crystal grains are elongated by the aspect ratios of more than four times in the longitudinal cross section parallel to the applied stress. The reason is in the fact that the fatigue cracks have to propagate mainly along the wavy slip bands independently of the grain boundaries resulting in high resistance to crack propagation.View full abstractDownload PDF (1531K) -
Seiichi NIWA1978 Volume 28 Issue 8 Pages 418-430
Published: August 30, 1978
Released on J-STAGE: July 23, 2008
JOURNAL FREE ACCESSDownload PDF (4495K)
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