| 摘要 |
FIELD: metallurgy. ^ SUBSTANCE: plate from aluminium alloy consists of 6.8-8.5 wt % Zn, 1.75-2.3 wt % Cu, 1.5-1.84 wt % Mg and up to 0.25 wt % at least of one of Zr, Hf, Sc, Mn and V, and if necessary, additives crushing the grain, and the rest includes aluminium and inevitable impurities; at that, plate has the thickness of not more than 2.00 inches. Plate has the ratio between yield strength and failure viscosity, which meets the following equation: FT_LT ëÑ -4.0* (TYS_L)+453. Plate has TYS_L that is at least 80 ksi and FT_LT that is at least 100 ksiêÜ inch, where TYS_L - tensile yield strength of the plate in direction L, in ksi, which is measured in compliance with ASTM E8 and ASTM B557, FT_LT - failure viscosity (Kapp) of the plate in flat stressed state in direction L-T, in ksiêÜinch, which is measured in compliance with ASTM E561 and B646 on specimen of aluminium alloy with central crack in position T/2 of the plate; at that, specimen has the width of 16 inches, thickness of 0.25 inches and initial length of preliminary fatigue crack of 4 inches. ^ EFFECT: plates are made from aluminium alloys having high failure viscosity at maintaining the acceptable strength level. ^ 32 cl, 10 dwg, 10 tbl, 4 ex |
