High Vacuum Creep Forming and Flattening Services

 

Titanium Alloys in Aerospace Applications

Titanium alloys are widely utilized in aerospace applications, such as load-bearing airframe components, due to their exceptional mechanical strength, corrosion resistance, and lightweight properties. However, titanium alloys present challenges when machining / forming at room temperature due to their inherent material characteristics.

 

High Vacuum Creep Forming: Improving Formability

Vacuum creep forming is an effective method to enhance the formability of titanium alloys and minimize spring-back during the forming process. This process involves maintaining the workpiece against a die or fixturing for a specified dwell time under controlled vacuum conditions after the initial forming stage. The result is reduced residual stress, minimal spring-back, and consistent repeatability.

 

Creep Forming and Flattening Titanium in High Vacuum

To achieve high-quality finished parts, several key steps are essential:

• Vacuum Furnace Preparation: Pre-bake the vacuum furnace at 2,400°F before the process and maintain vacuum levels in the 10⁻⁵ Torr range to avoid surface oxidation and the formation of the alpha case.
• Fixture Preparation: Bake fixturing components at least 150°F higher than the creep flattening temperature to prevent contamination.

 

Stress Relief Integration

In-process stress relieving can assist to minimize material movement seen during the machining process and eliminate cold working. Since stress relieving and creep flattening often occur at the same temperature, this dual process not only relieves internal stress but also reshapes the part for final machining. Additionally, vacuum conditions during this process facilitate hydrogen extraction, adding degassing benefits to stress-relieving and shaping.

 

Typical Temperatures for Creep Forming and Flattening

Creep forming or flattening of titanium typically occurs above 1,000°F, with optimal ranges between 1,250°F and 1,350°F depending on the alloy. Precise temperature and hold times vary by composition, but a two-hour hold at temperature, monitored using work thermocouples, is generally sufficient.

 

Fixturing for High Vacuum Creep Forming and Flattening

Graphite tooling is ideal for creep forming and flattening titanium parts. Graphite accommodates thermal expansion and contraction with minimal friction, ensuring smooth material movement in the desired direction while maintaining critical dimensional tolerances. While metallic fixtures can be used, graphite is preferred for its superior performance in these applications.

 

---

Unique Capabilities

• Complete line of vacuum furnaces ranging from small R&D lab sized to large 48 foot long
• Extensive load sensor capability (48 thermocouples)
• Precision ground graphite fixturing used as a base or mold

 

Components Processed

• Sheet
• Plate
• Weldments
• Forgings
• And more!

 

Materials Processed

• Titanium

 

 

Ask the Expert:

Solar Atmospheres of Western PA’s Director of Sales Discusses Creep Flattening Titanium