Crack propagation in aluminium gas cylinder neck material at constant load and room temperature

Sustained tensile load tests were carried out at room temperature on small circumferentially cracked cylindrical specimens taken from the necks of aluminium gas cylinders. Comparison was made of the resulting time to failure of specimens of aluminium alloys 6351, 6061 and 6351 with lead impurity levels exceeding 200 ppm. The effect of superimposing a small number of interruptions to the sustained load was also examined. With a few exceptions the 6061 alloy withstood the sustained loading for significantly longer periods than the 6351 alloy. The presence of lead substantially reduced the time to failure, as did also the addition of a small number of fatigue cycles.