Abstract
The materials examined were a 99.5 per cent aluminium, the 2 1/4 per cent magnesium alloy to B.S. 1476: 1955 NE4, the 3 1/2 per cent magnesium alloy to B.S. 1476: 1955 NE5, a 1 1/4 per cent manganese alloy and the magnesium-silicide alloy to B.S. 1476: 1955 HE30, all being in the form of extruded rod. Excepting for the HE30 alloy, which was fully heat-treated, all tests were carried out with the material in the as-extruded condition.
Short-time data covers a temperature range of 20°-250°C, the stress-rupture curves, which mostly extend up to 10 000 h, relating to temperatures of 100°, 150°, 200°, and 250°C. Creep tests, a number of which were taken into the tertiary stage, have been carried out at 200° and 300°C for the 1 1/4 per cent manganese alloy and temperatures employed for the HE30 alloy were 100°, 150°, and 200°C. Stress-rupture tests still in progress and creep data for the remaining three materials will be reported in an addendum.
Stress-temperature curves are plotted which enable a direct comparison to be made of the effect of temperature on rupture strength for specified amounts of time.
The paper concludes with a fairly detailed report of the effect of time, stress, and temperature on the microstructure and discusses the types of fracture encountered.
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