Aluminium alloy cast shell development for torpedoes

The sand-cast aluminium alloy cylindrical shells were developed for the advanced experimental torpedo applications. The components had intricate geometry, thin-walled sections, and stringent property requirements. The casting defects, such as shrinkage, porosity, incomplete filling of thin sections, cold shuts, inclusions and dimensional eccentricity, etc were found in the initial castings trials. Improvements in casting quality were achieved through modified methodology, selective chilling, risering, and by introducing ceramic-foam filters in the gating system. The heat-treated and machined components met radiographic class 1 grade C/E standards, mechanical properties to BS1490 specifications, and leakage and hydraulic pressure test requirements relevant for such applications.