Grain refinement of copper base alloys

The grain refinement characteristics of four low-lead and lead-free copper base alloys for plumbing applications were investigated. These are leaded yellow brass (C85800), SeBiLOY III (C89550), silicon brasses (C87500 & C87800) and silicon bronzes (C87600 & C87610). Boron and zirconium were found to be the most effective grain refiners for copper alloys produced using the permanent mold cast processes. The study indicates that the type of grain refiner to be used is dependent on the alloy type, alloying constituents and their content. After grain refinement, hot tearing resistance of the alloys was improved but mechanical properties remained unaffected. Alloys refined with boron are prone to the formation of hard spots, which will have adverse effect on the surface quality of the castings during perishing and buffing.