Abstract
Effect of silicon on the mechanical properties of ferrite was studied and the result summarized as follows:
(1) Silicon is the very effective element for enhancing both the tensile strength and Izod impact value of ferrite.
(2) The impact value of pure iron rapidly drops when the silicon becomes in excess of 2%. The reason does not lie in that the toughness of ferrite has decreased as the silicon dissolved in ferrite, but in that the grains become extraordinarily greater with the increase of silicon.
(3) Consequently, good toughness may be imparted to the high silicon steel with 2-4% Si, when a grain refinement is devised by adding a third element or by forging operation. Seeing from the result of the present study, the grain control is essential in using a large quantity of silicon as alloying element in structural steels. For instance, the following alloy steel (C 0·03%, Si 2·5%, Ni 5·0%) was obtained which shows excellent mechanical properties; tensile strength 85kg/mmmm2, elongation 40%, reduction of area 60% and Izod impact value 90 ft-lbs.
