A comparsion of grain refiner master alloys for the foundry

Grain refiners are widely used in the foundry. They are considered to provide benefits in a number of ways including improved feeding during solidification, reduced and more evenly distributed porosity, and reduced hot tearing. There are a number of refiners for the foundry industry used industrially or mentioned in the literature. A programme of laboratory tests has been carried out, which started with a pre-screening of a wide range of potential refiners, using standard laboratory grain refining tests. The better performing refiners were then tested in a permanent mould casting, designed to simulate conditions at the spoke-rim junction of a wheel casting. Results are presented in terms of the effect of refiner on grain size, hot tearing and porosity distribution. Recommendations are made in terms of the optimum refiners for the foundry.