Abstract
The authors investigated some important industrial properties of a series of Fe-CrAl alloys containing 5-30% Cr and 1-7% Al, such as hardness. specific resistance, its temperature coefficient, oxidation resistance, specific weight, thermal expansion and magnetic transformation.
The authors, again, examined effect of grain growth on mechanical properties, since the alloys have unusual phenomenon of grain growth at high temperatures. The result of experiments was summarised as follows:
In the hardness test, it was found that the most suitable heat treatment for softening these alloys is heating to about 800°C followed by rapid cooling. From the result of measuring the specific resistance, the ternary specific isoresistance curves were completely plotted, In the oxidation test, in case the Al content is in excess of 3%, the 15% Cr addition is sufficient for enhancing high temperature oxidation resistance but further addition yields little improvement. Besides, in Fe-Cr-Al alloys with the high-Cr and high-Al content, a remarkable grain growth is observed by heating to temperatures above 900°C and they become very brittle. Therefore full consideration should be made in annealing or using them at high temperatures.
