Journal of Japan Institute of Light Metals

Some thoughts on disasters

Yoshinobu NAKAO

1984Volume 34Issue 4 Pages 213-214
Published: April 30, 1984
Released on J-STAGE: March 14, 2011

DOIhttps://doi.org/10.2464/jilm.34.213

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Effect of cutting conditions on the machinability of magnesium casting alloys

Tsuneya FUJII, Yoshisada KOBAYASHI

1984Volume 34Issue 4 Pages 215-220
Published: April 30, 1984
Released on J-STAGE: March 14, 2011

DOIhttps://doi.org/10.2464/jilm.34.215

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A machinability test of MC2 (AZ910) and MC5 (AM100A) castings was carried out in comparison with AC4CH (A356) castings for automobile wheels. Effects of such cutting conditions as cutting speed, feed, depth of cut and side-cutting-edge-angle on thrust, feed and principal components of cutting force and on cutting ratio were tested. MC2 and MC5 magnesium alloy castings have cutting efficiency 1.5 to 2.0 times as large as that of AC4CH aluminum alloy castings. Magnesium alloy castings are economical in practical machining.

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Aging behavior of commercial Al-Cu-Mg alloys

Ichiro ARAKI

1984Volume 34Issue 4 Pages 221-226
Published: April 30, 1984
Released on J-STAGE: March 14, 2011

DOIhttps://doi.org/10.2464/jilm.34.221

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Aging phenomena of 2024 and 2324 alloys were studied. The alloys were solution treated at 500 °C for 1 hr and quenched into iced water, quenched directly down to 190 °C, or step quenched to 300 ° to 400°C and then to 190 °C. The alloys were finally aged mainly at 190 °C. Both alloys directly quenched have the most excellent mechanical properties in the alloys quenched in different ways. It is suggested from the fact that heterogeneous precipitation of S' phase on insoluble dispersoids (T phase, Al₂₀Cu₂Mn₃) is suppressed. Age-hardenability of the alloys step quenched is markedly reduced due to the precipitation of S phase on the above dispersoids during step quenching. 2024 alloy T6-treated has strength slightly higher than 2324 T6-treated, because Mg₂Si would also precipitate in 2024 alloy.

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Oyer-aging structures of an Al-4%Cu-4%Mn alloy

Hisashi SUZUKI, Goroh ITOH, Katsumi KOYAMA

1984Volume 34Issue 4 Pages 227-230
Published: April 30, 1984
Released on J-STAGE: March 14, 2011

DOIhttps://doi.org/10.2464/jilm.34.227

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Al-4%Cu-4%Mn alloy specimens were chill-cast, homogenized at 793 K for 0.6 ks, water-quenched, preaged at 473 K for 60 ks and subjected to over-aging at 623 K. The crystal structure and precipitation process of ternary phase (named T') appearing during final aging and being effective for the suppression of over-aging of this alloy, were studied by transmission electron microscopy including selected area diffraction. The T' is an orthorhombic crystal (a = 0.339 nm, b = 1.24 nm and c= 1.20 nm) and has an orientation relationship with the matrix : (100) _T'//(100) _Al, [010] _T'//[010] _A. It was found that T' nucleates on the periphery of θ' which has formed during pre-aging. Cold working before pre-aging was performed based on this result. The cold working was significantly effective for an increase in the number density of T', leading to an increase in hardness after over-aging.

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Discontinuous deformation in some binary aluminum alloys

Yoshikazu HOSOI, Katsuo SAITO, Isao ITOH, Takeo HIKAGE

1984Volume 34Issue 4 Pages 231-235
Published: April 30, 1984
Released on J-STAGE: March 14, 2011

DOIhttps://doi.org/10.2464/jilm.34.231

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Tension tests of aluminum and some binary aluminum alloys were made at room temperature at a strain rate 2.2×10^-3s^-1. Pure aluminum and Al-Mg and Al-Zn alloys show a yield phenomenon analogous to steel, but not in Al-Si and Al-Cu alloys. Discontinuous deformation known as Portevin-LeChatelier effect is observed significantly in Al-Cu and Al-Mg alloys, but not in pure aluminum and Al-Si alloy. Following the P.L. effect, other two types of discontinuouq deformation were found. They are cyclic in the load-elongation curve of Al-Cu and Al-Mg alloys.

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Deep drawability of work hardened aluminum and aluminum alloy sheets

Eiki USUI, Takashi INABA

1984Volume 34Issue 4 Pages 236-243
Published: April 30, 1984
Released on J-STAGE: March 14, 2011

DOIhttps://doi.org/10.2464/jilm.34.236

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The deep drawability, scouring and earing ratio of non-heat-treatable and work hardened aluminum alloys 1100, 3003, 3004 and 5052 were investigated. The priority of factors governing the drawability depends on lubricating conditions. In the well lubricating condition, n-value is a potential factor. The deep drawability is developed by a final heat treatment. Tensile strength is important in the poor lubricating condition, because of a potential effect of friction stress and of a moderated effect of heat treatment. High strength materials such as 3004 and 5052 therefore show better drawability than 1100 and 3003. The surface oxide film particularly Mg oxide film is a factor governing scouring. It is important to minimize the Mg oxide film in the poor lubricating condition.

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The development of a 2 piece aluminum disc wheel for automobiles

Shouji FUJIWARA, Noriyuki AOKI, Tetsuo IWAMOTO, Yoshihiro MAEDA, Kiyos ...

1984Volume 34Issue 4 Pages 244-249
Published: April 30, 1984
Released on J-STAGE: March 14, 2011

DOIhttps://doi.org/10.2464/jilm.34.244

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Chemical Characterization of Aluminum Surfaces

Takao MURAKAWA

1984Volume 34Issue 4 Pages 250-261
Published: April 30, 1984
Released on J-STAGE: March 14, 2011

DOIhttps://doi.org/10.2464/jilm.34.250

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