高强度铝合金小裂纹疲劳扩展特性

THE SMALL CRACK PROPAGATION PROPERTIES OF HIGH STRENGTH ALUMINUM ALLOYS

讨论面心立方多晶铝合金的表面局部塑性变形特点以及由此造成的表面小裂纹疲劳扩展特性．理论表明：当小裂纹位于试样表面时，周围环境对表层晶粒所施加的约束作用要小于对内部晶粒的约束作用．

Surface local plastic deformation of high strength alumunum alloys and its effect on the propagation of small cracks are discussed. It is proved that when small cracks are located at the surface of specimen, due to the relatively weaker constraint from the surrounding grains at the surface,they can grow more easily than they propagate in the inner part of material.This results in the failure of LEFM.The experimental data demonstrated the correctness of the theory in this paper.