US Patent 10239156 Multi-density, multi-property turbine component

A method of forming a metal component having different regions containing different grain sizes and in porosities is by additive manufacturing. The method includes spreading a layer of starting powder on a temperature controlled moveable platform in a heated chamber with atmosphere and temperature control. Selected areas of the powder are melted and solidified with a computer controlled focused energy beam. The cooled platform is then indexed down and the process repeated. The grain size of the melted and solidified region can be controlled by the cooling rate during solidification which, in turn is controlled by the temperature of the chamber and the temperature of the cooled moveable platform.