Abnormally High Fatigue Strengths in Aluminium Alloy Extruded Bar

IN 1932, Matthaes 1 reported that the tension properties of aluminium alloy extrusions in the longitudinal direction were significantly greater than in the transverse direction, and it is now well known that both the ultimate tensile stress and proof stress values may be 20–30 per cent greater than the respective values for rolled or forged material. However, it has been observed 2 that the fatigue properties are little affected by the extrusion process. In view of this the following results are of interest.