Effect of hot isostatic pressing on fatigue strength of cast steel

Abstract

AbstractThe inadvertent occurrence of porosity in cast steel has tended to restrict the use of casting as a means of producing components requiring a high degree of structural integrity. Evidence is now presented showing that hot isostatic pressing is an effective way of removing internal porosity, resulting in a marked improvement in mechanical properties, particularly the fatigue strength. The deleterious effect of interdendritic porosity on the mechanical properties of cast steel is shown, together with the improvement in the fatigue strength after hot isostatic pressing at 1100°C at a pressure of 148 MPa. The independent effect of temperature was determined by subjecting ‘sound’ cast steel specimens to a homogenization heat treatment at the same temperature and time interval that were used during hot isostatic pressing. The significant improvement in fatigue strength reported may be due to a change in non-metallic inclusion morphology. The added cost of the process may be justified where a high degree...