The growth behaviors of short through cracks (0.2 < △a < 2.2mm) and long cracks are compared using CT type specimens in aluminum-lithium alloy 8090 T651. It is found that the short cracks grow much more than lo...The growth behaviors of short through cracks (0.2 < △a < 2.2mm) and long cracks are compared using CT type specimens in aluminum-lithium alloy 8090 T651. It is found that the short cracks grow much more than long ones and are observed to grow at the stress intensity ranges far below the long crack threshold. The distinction of growth bahavior between short and long cracks is attributed to the difference of their crack closure effect. The growth behavior of short cracks can be rationalized with that of long ones in terms of effective stress intensity ranges. The upper demarcation value of short through cracks for aluminum-lithium alloy 8090 is presented.展开更多
The crack propagation resistance for alloy 8090 sheet decreases with the increase of content of Na and K impurities.An improvement over the fracture toughness and crack initiation resist- ance for the alloy containing...The crack propagation resistance for alloy 8090 sheet decreases with the increase of content of Na and K impurities.An improvement over the fracture toughness and crack initiation resist- ance for the alloy containing Na and K within certain limit may be made by adding 0.05% Ce.This beneficial modification would not be manifested if the alloy contained more Na and K.One of the reasons why Na and K injure the toughness of the alloy might be due to that they cause the precipitation of T_1 phase along grain and subgrain boundaries and accelerate the abnormal growth of recystallized grains.展开更多
文摘The growth behaviors of short through cracks (0.2 < △a < 2.2mm) and long cracks are compared using CT type specimens in aluminum-lithium alloy 8090 T651. It is found that the short cracks grow much more than long ones and are observed to grow at the stress intensity ranges far below the long crack threshold. The distinction of growth bahavior between short and long cracks is attributed to the difference of their crack closure effect. The growth behavior of short cracks can be rationalized with that of long ones in terms of effective stress intensity ranges. The upper demarcation value of short through cracks for aluminum-lithium alloy 8090 is presented.
文摘The crack propagation resistance for alloy 8090 sheet decreases with the increase of content of Na and K impurities.An improvement over the fracture toughness and crack initiation resist- ance for the alloy containing Na and K within certain limit may be made by adding 0.05% Ce.This beneficial modification would not be manifested if the alloy contained more Na and K.One of the reasons why Na and K injure the toughness of the alloy might be due to that they cause the precipitation of T_1 phase along grain and subgrain boundaries and accelerate the abnormal growth of recystallized grains.
