R. Hardin, Z. Lin, and C. Beckermann

Under the present acceptance standards for steel castings, it is entirely possible for a small shrinkage defect to be passed whereas the larger centerline shrinkage causes a rejection of the casting. A large level of discontinuities located in the center of a casting section may not affect its mechanical properties or fatigue performance, while a small discontinuity near a surface may have a significant effect on fatigue life. Consequently, design engineers uses large safety factors, over-specify the casting making it heavier, less casting friendly, expensive and more time consuming to produce, or they reject the use of steel castings altogether for more expensive fabrications that often have longer lead-times.

Simulation tools have been developed and are now being applied to military and commercial steel castings. Starting with the liquid steel and the mold, the location and amount of shrinkage discontinuities formed during the casting process are predicted, and then included in the analysis to evaluate the load-carrying capacity and fatigue durability of cast components. The ability to design steel castings with non-uniform mechanical properties and examine the tradeoffs between manufacturing costs and structural performance will reduce design process iterations. Applications will allow a discontinuity where it can be tolerated while ensuring soundness where needed.