Study of deformation and aging behaviour of iron–silicon alloys

Axisymmetric compression tests were conducted at room temperature on silicon steels in which the content of this last element varied from 1.9 to 6.3 wt.% to study their behaviour while being deformed. The tests were performed in a specially designed machine able to control the strain rate profile and the amount of deformation. The specimens used in the test were machined directly from castings and were treated prior to testing for 15 min at different temperatures within the 700–1000 °C range; these samples were then cooled at three different rates. Testing was conducted on samples just after cooling and at 2, 6 or 24 h after treating. 57Fe Mössbauer spectroscopy analyses were conducted in selected samples to evaluate the degree of order of the alloys. It was found that the strength of the material depends on the amount of silicon added and on the cooling rate. Double deformation tests indicate that the steels are subjected to aging, 57Fe Mössbauer spectroscopy points out that ordering of the material is related with it, although the nature of such an aging behaviour is not clear.