Hideo Yamaguchi

ON THE WELD CRACKING OF ALUMINUM AND ITS ALLOYS

The cracking which sometimes occurs in the weld bead and in the adjacent metal is the most troublesome problem which arises in the fusion welding of aluminum and its alloys.This work was carried out on binary alloys of aluminum with silicon, copper, magnesium, zinc, iron, manganese and chrome, all the alloys being prepared from aluminum with the purity of 99.99% and alloying elemments of the highest purity obtainable.The results obtained are summarized as follows:1) The welding crack of the oxyacetylene process is severer than that of the Argon-arc process.2) Cracking differs with the support distance of restraint.3) Aluminum alloys with iron, manganese and chrome are not subject to cracking by oxyacetylene process welding under very severe condition of restraint.4) Binary aluminum alloys with wide range of solid solution such as magnesium, copper, silicon and zinc are very sensitive to cracking. The cracking becomes severe with the addition of these alloying element at first and after reaching a maximum point decreases till its reaches a constant value.

ON THE MELDABILITY OF Al-Mg ALLOYS

echanical properties of welded Al-Mg Plates differ greatly by the welding methods.The results oftained are summarized as follows:(1) Argon arc method is recomended for Al-Mg alloys, for mechanical propertis welded by this method are the best.(2) Metal arc and oxyacetylene gas method are not recomended for thick Al-Mg plates. Mechanical properties of deposit welded by these methods are extremely inferior to that of mother plates, due to the flux used by those welding methods.(3) Al-Mg thick plates welded by oxyacetylene gas method happen to have hair crack, owing to the welding heat.

ON THE CHARACTERISTICS OF 2S HALF-HARD SHEETS MANUFACTURED BY THE METHODS OF BOTH ANNEALING AND STRAIN HARDENING

There are two methods of manufacturing the various tempers of 2S-aluminum sheet, one of which is the strain hardening method and the other is the annealing method. The former is the normal method and has used in America and the latter is abnormal, but frequently used in our country.In the present paper, the difference of the characteristics of 2S-aluminum sheets tempered by above both methods are investigated.The results obtained are as follows:1) In the case of tempering by the strain hardening method, the higher final annealing temperature hastens the hardening and lowers the elongation, and also erichsen value.2) When the soft materials are strain hardened, the general elongation are rapidly reduced and the almost elongation concentrated to the broken point. Therefore, the local elongation become comparably high.3) Tne recrystallization textures of cross rolling are quite different from that of normal rolling, so that the softening curves and earing behavior of both case are quite dissimilar.4) The directionality of sheet tempered by strain hardening method is less fhan that by annealing method at the same temper. In the case of strain hardening, the lower final annealing temperature is favourable for directionality.5) The drawnability of sheet by the annealing mefhod is superior to that by strain hardening method.

ON THE TACK WELDS OF ALUMINUM PLATE

The studies on the effects of tack welds of aluminum plate were carried out. The results obtained are as follows.Using closely spaced tack welds.(1) Buckling and distortion can be minimized and welding work is easy.(2) The cracking occurs in thick plates, but it can be reduced by choosing proper welding condition and material composition.