Fundamental experiments on air cooling, spray cooling and hot rolling of aluminum are performed for determining the heat transfer coefficients in hot rolling. And using these heat transfer coefficients, the temperature change of aluminum strip in hot strip mill line is calculated by the method of finite differences. The calculation results show that except in the roll gap, there is almost no temperature difference between the surface and the cross section center of the strip in case of aluminum, unlike in case of steel.
Therefore, for computer control, temperature model for calculating the mean strip temperature is necessary.

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Aluminum which had been i) wire brushed, ii) emery paper polished and electropolished, and iii) wire brushed and electropolished was diffusion welded. The morphology and distribution of the oxide are strongly influenced by the surface treatment. When the faying surface subjected to the treatment i) is welded, a number of oxide particles distribute within a zone 1 to 3μm in thickness along the bond interface. The zone consists of many small grains less than 1μm in diameter. The formation of the zone is attributed to plastic deformation and a number of oxides introduced by wire brushing. The zone involving the oxide has a harmful effect on the bond strength, because the surface treatment i) results in a bond strength much lower than the treatments ii) and iii). When faying surfaces subjected to the treatments ii) and iii) are used, on the other hand, thin oxide films 20 to 40nm in thickness are observed only along the bond interface. The portion of the bond interface where the oxide is broken up extends when faying surfaces are subjected to the treatment iii) rather than subjected to the treatment ii). A higher bond strength is obtained by using the treatment iii).

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Diffusion welding of commercially pure aluminum (JIS A1200) to mild steel (JIS S20C) was performed using various insert materials such as Ni and Al-Cu-Mg alloy (JIS A2024) foils. A Ni foil was at first diffusion welded to steel at 850°C for 30mn at 0.065kg/mm² in welding pressure. This joint results in tensile strength higher than that of the Al base metal. Diffusion welding of Al to the overlayed steel with Ni foil was then accomplished employing an insert material of 2024 alloy foil. The joint welded at partially melting temperature (520°C) of 2024 alloy for 30mn at 0.065kg/mm² in welding pressure shows 85% of tensile strength to the Al base metal and the best Charpy impact value. The interlayer which consists of intermetallic compounds of Al₃Ni (β-phase) and Al₃Ni₂ (γ-phase) is formed at 2024 alloy side and Ni side in the bonding interface respectively. The mechanical strength lowers with increasing the thickness of this interlayer.

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Long time fluxless brazing tests on 3004 alloy and 3003 and high purity Al-1Mn-1Mg alloys for comparison were carried out mainly in vacuum (2×10^-5torr) at 590 to 600°C using a BA 4004 clad brazing sheet. 3003 base metal has long time brazability superior to 3004 base metal. The fillet on 3003 base metal disappears after brazing for 180min at 600°C. While high purity Al-1Mn-1Mg alloy shows sufficient fillet after brazing for 180min, which confirms that the use of pure base metal is markedly effective to improve long time brazability of Al-Mn-Mg alloy. A decrease in mechanical strength of 3004 base metal is responsible to Mg vaporization during vacuum brazing. The decrease in strength is prevented a little by the carrier gas brazing method (N₂ gas: 10^-1torr).

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In turning of Al-7%Si cast alloy, the built-up edge appears intensely. Critical cutting temperature of disappearance of this built-up edge is reduced by the addition of Mg or Cu which is a main alloying element. This effect by the addition of a small amount of Mg is more remarkable than that of Cu. For instance, the built-up edge of T₆ treated alloy disappears at cutting temperature about 460°C and 400°C by the addition of 0.2% and 0.8%Mg. However, this critical temperature by 1%Cu addition is about 460°C, but its temperature is reduced about 400°C by 4%Cu addition. The cutting temperature is elevated by the addition of Mg or Cu. Although its effect by the addition of a small amount of Mg is more remarkable than that of Cu, but an addition of 2% to 4% of Cu permits higher cutting temperature than that of 0.8%Mg addition.

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