Characteristics of Surface Crack Growth in Rotating Bending Tests of Age-hardened or Annealed Al-alloy

Abstract

Rotating bending fatigue tests were carried out to evaluate the characteristics of surface crack growth in an age-hardened Al-alloy and an annealed Al-alloy The main results obtained are as follows : (1) The rack growth rate in an annealed Al-alloy is expressed by the following equation. dl/dN = Cσⁿ 1 (C, n : material constants ) The number of cycles to failure of a plain specimen can be estimated by this equation. (2) In case of an age-hardened Al-alloy, a surface crack propagates rapidly along a slip band when the crack is short, and then the crack propagates zigzag, in that time the increase in the crack growth rate is low.