The effects of chemical compositions on the formation of residual stress in iron castings were investigated by strain hindering method which was reported previously. The formation of residual stress in white pig iron castings as well as the effects of silicon added to white pig iron and phosphorus added to grey pig iron on the residual stress formation were examined.
  The results obtained are as follows;
  1. The process of residual stress formation in castings of white pig iron resembles to that of grey cast iron but differs in the growing rate of stress below the transformation temperature, i. e., the stress development in the former is much larger than in the latter. This difference may be attributed, to a large extent, to the difference in Young's modulus.
  2. So far as these experiments are concerned, the stress relaxation by plastic deformation is not detectable in white pig iron castings below the transformation temperature, so about 650°C is considered to be so-called “critical temperature”.
  3. Addition of silicon in white pig iron decreases the residual stress as the silicon content increases up to 3.8%, but further increase up to 7% has no effect.
  4. Increase of phosphor content in grey cast iron rather increases the residual stress, though in a little amount.