Heat Treatment of Titanium Alloy

With high-strength and light-weighing properties, titanium alloy?is no doubt one of the most popular?metal AM materials?for metal printing.

Aside traditional manufacturing, titanium alloy parts?by metal 3D printers also requires stress relief annealing and castings in a vacuum furnace or an argon atmosphere furnace. Heat treatment is a key process in the manufacturing process of titanium alloy parts, and its final performance depends to a large extent on whether the heat treatment is carried out correctly.

• Protect Atmosphere:

Since titanium alloy is an extremely active metal, it is easily polluted by carbon, oxygen?and?hydrogen,?which will deteriorate the properties of the alloy. Therefore, vacuum furnace or argon-protective-atmosphere furnace is basically used for heat treatment of titanium alloy. Among them, vacuum furnace is?the preferable.

• Atmosphere Pressure Control:

One of the main parameters of?vacuum heat treatment?of metal 3d printing?is the vacuum working pressure. The aviation industry standard stipulates that in the process of vacuum annealing, in order to avoid vacuum surface corrosion caused by too low vacuum pressure, the vacuum working pressure should generally be controlled at not less than 2×10-3Pa . Some use high-purity argon for partial pressure control.

• Gas Purity Control:

The inert gas argon can be used as the heating medium of the protective atmosphere, and can also be used as the quenching medium during vacuum solution treatment. Due to the relatively high chemical activity of titanium, there are also higher requirements for the purity of argon. Pure argon with a purity of not less than 99.99% is generally not suitable for heat treatment of titanium alloys.

• What Oxide to Remove:

Relevant standards at home and abroad have not stipulated the temperature of the workpiece after heat treatment in the vacuum furnace. The navigation mark stipulates that the printed parts after vacuum heat treatment should be air-cooled below 200 °C. When a light yellow oxide film appears on the surface of titanium parts heated in inert gas or vacuum, it may not be removed; if there is a light blue, blue or gray oxide film on the surface of the part, it must be removed according to the regulations of the air furnace.

• Oxide Removal Methods:

The oxide layer on the surface of titanium alloy printing parts must be removed, and the removal methods include pickling, chemical milling, sandblasting and machining.

Through heat treatment, titanium alloy printed parts with higher strength and better plasticity can be obtained.

For any question regarding post-processing of titanium alloy, please feel free to contact us!