Linking Machining Response of Titanium Billet to Upstream Thermomechanical Processing

Abstract

The texture of a typical titanium billet has evolved during the primary breakdown forging steps and acts as a 'finger print' of the forging process. This has a lasting legacy and can have a significant influence not only on the machining process but also the material's in-service performance. This paper reports the force feedback on machining tools during face turning of a titanium (Timetal® 54M) billet and how variation in feedback level appears directly linked to processing history. During cutting, higher forces are required in regions where the billet has received greater amounts of total strain during upstream forging stages. Furthermore, subsurface microstructural analysis of the machined surface has revealed how upstream processing, through the development of specific crystallographic texture components, has a direct impact on the level of subsurface damage caused by machining.