65/35黄銅鋳塊の残留βの挙動と再結晶粒度

抄録

In our country, the chill cast and the bran cast moulds in manufacturing wrought brass billets are widely used, and also the continuous casting method is now being used. In 65/35 brass, cast into book-mould by the above-mentioned casting methods, some segrgations, were found in the ingots containing more or less of the beta phase. The residual beta was almost always of a massive shape in the bran cast or of a striped form in the continuous casting method. The beta in the cast ingot was is dissolved in alpha by long soaking or annealing, and this disappearance of the beta phase was accelerated by cold-rolling before heating. When a cold-rolled continuous cast ingot was heated to recrystallization temperature, fine recrystallized grains were frequently produced along the laminated residual beta phase, and this phenomenon seemed to be the effect of suppression of the grain growth due to laminated beta. When the sample, slightly cold-rolled after being partially recrystallized, was annealed, coarse grains were formed around the residual beta particle. In order to prevent the appearance of mixed grains, therefore, it is important that the beta should be eliminated by adeguate soaking or annealing prior to the final rolling.