Abstract
The purpose of this investigation was to compare, on the same basis, the mechanical and high-temperature properties of various cast irons. The irons used ranged from low-Si irons, through high-Si irons, to high-Al irons, containing small amount of alloying elements, Cr, Mo, Al, Cu. Growth and scaling characteristics of those irons were studied at 900°C for 300 hours. The strength was measured by as-cast specimens and heated specimens at 900°C for 300 hours, and observations were made on changes in the mirostructure.
The results obtained were as follows:
(1) Small addition of Cr was effective in resisting to growth, but not effective in resisting to scaling and in maintenance of strength at high temperature. And it merely affected the strength after long heating at high temperature.
(2) Mo was merely effective in resisting to growth and scaling, but remarkably effective in maintenance of strength at high temperature.
(3) Cu was merely effecttive only in resisting to scaling, but it was evil to growth and mechanical properties at high temperature.
(4) Small addition of Al increased growth and scaling, but the iron containing from 4 to 7 per cent Al considerably resist to growth and scaling.
(5) The 5 per cent Si iron containing 4 per cent Al and 1 per cent Cr has greater resistance to scaling and growth at 900°C. The growth of this iron was almost unmeasurable and its scaling resistance at 900°C was about equivalent to that of 20 per cent Cr cast iron. And its strength not only decreased but merely increased after long heating at high temperature.
