Cleaning process of titanium alloy forging

The oxide scale and α-shell layer formed during the forging heat treatment of all titanium alloys are very brittle, and induce cracks in the subsequent forging or in the final forging or cause tool wear in the subsequent machining process. Therefore, it is recommended that titanium alloy processing remove scale and α-shells between continuous forgings, and scales and α-shells must be removed before forgings are delivered to users.

The cleaning technology of F9 Titanium Forgings has two aspects: one is the removal of oxide skin; the other is the removal of α shell. The scale can be removed mechanically, such as sandblasting; or chemically, such as molten salt derusting. The choice of rust removal method depends on the size, complexity and cost of the part.

Sandblasting is an effective method to remove rust scales. It can remove scales with a thickness of 0.13-0.76mm. It can use 100-150 mesh zircon sand or steel sand, and the air pressure can reach 275Pa. Although sand blasting is available for forgings of various sizes, it is mostly used for medium and large titanium alloy forgings. Sandblasting equipment can use abrasive drums, shot peening or sandblasting units. After sandblasting, it is pickled to remove the alpha shell.

Molten salt derusting is another effective method for removing scale, and pickling removes the alpha shell along with it. 1. The flow chart of rust removal and pickling by molten salt, solution composition and related parameters. The frame used for molten salt derusting is generally made of wood, titanium or stainless steel, in order to prevent electric potential from being generated between the workpiece and the frame, resulting in electrical erosion or arcing of the workpiece. Molten salt derusting is often used for medium and small forgings. In the case of large batches of forgings, the operating system can be fully automated.