Depending on the application and part specifications, various amounts of finishing are required in the next step in the investment casting process. If necessary, excess metal is removed, the part surfaces are polished and other work may be done. In many cases, the castings are heat treated. Heat treating is the process of heating, warming and cooling the castings to achieve specific properties. While it does not change the shape or composition of investment castings, it will improve part performance by changing the microscopic structure of the metal. Among the benefits are greater corrosion resistance, abrasion resistance and hardness.