| 摘要 |
PURPOSE:To produce a zinc hot dipped steel plate having plating layers of good workability by rolling a zinc hot dipped steel plate of which the surface layers consist of eta zinc layers at temps. lower than the recrystallization temp. of the zinc layers then subjecting the zinc layers to recrystallization under heating. CONSTITUTION:A zinc hot dipped steel plate which is obtained by drawing a steel plate out from a zinc hot dipping bath, and preparing the coating weights of zinc by a gas blowing method and of which the surfaces consist of eta zinc layers is rolled at 10-60% draft at temps. lower than the recrystallization temp. of the eta zinc layers, whereby the crystal grains of the eta zinc layers on the surfaces are disintegrated approximately to an amorphous state and the impurities existing at the grain boundaries are dispersed. Thereafter, the steel plate is subjected to recrystallization under heating at a 150-400 deg.C temp. range at which the surfaces maintain the eta zinc layers, whereby the plating films are made into extremely fine crystalline structure and ductility and workability are markedly improved. |
