The Fracture Toughness of Cast High-Strength Steels

The mechanical properties of four cast high-strength steels, 4340, 15-5 PII stainless steel, and two maraging steels were examined. To provide a direct comparison with wrought steels split heats were prepared in which part of each heat was sand cast and the balance was forged and hot-rolled to plate. The K_Ic properties of the castings were comparable to the plate properties. Limited tests indicated that the cast steels also had reasonably good fatigue and stress corrosion cracking resistance. The castings showed surprisingly low Charpy values, which was attributed to notch acuity due to the more heterogeneous nature of the fractures in the cast structures. The overall results suggest that cast high-strength steels had satisfactory toughness and could be used in many applications.