Titanium alloys are one of today’s most widely used alloy metals in various applications. Their main component is titanium, but, of course, they also contain certain amounts of other elements to enhance properties for metallurgical purposes.
A lightweight, metallic element, titanium is often compared to steel in terms of strength. Its pure form comes in two solid crystalline forms:
- Alpha – this occurs at low temperatures and has a Hexagonal Closed Packed (or HCP) structure.
- Beta – this occurs at high temperatures and has a Body Centered Cubic (or BCC) structure.
The Process Of Forging Titanium Alloys
There are three major groups of titanium alloys:
- Alpha or near alpha
- Beta or near beta
- Alpha plus beta
Generally, beta titanium alloys are quite easier to forge than alpha titanium alloys and alpha-plus-beta titanium alloys.
To breakdown titanium ingots, the initial forging temperatures should be set to higher levels than the intermediate forging and finish forging settings.
Because of the necessary process control, forging of titanium alloys can be a lot more difficult than aluminum and steel alloys. Forging temperatures have to be controlled and monitored to achieve the appropriate mechanical properties. The temperatures involved include the furnace setpoint, adiabetic heating, die chill, and heat loss.
At high strain rates and temperatures, titanium can soften very rapidly and can result to flow localizations. Because of this, defects such as a crack or lap can appear. So, forging titanium is preferred at lower strain rates to prevent these critical flaws.
Methods Of Titanium Forging
Conventional titanium forging is performed at lower die temperatures, using less complicated and less expensive tools.
In iso-thermal titanium forging, on the other hand, the raw materials and forging dies are set to very high levels, a condition known as “iso-thermal,” accompanied with close monitoring and tolerance, special lubricants, super alloy tooling and equipment, and forging pressures and speed tracking.
Titanium Forging Applications
Because of superior attributes and properties, titanium forgings are used in several industries including:
- Military and marine (propeller shafts, submarines, saltwater aquariums)
- Aerospace (airframes, wing structures)
- Outdoor activities (knives, hunting tools, camping)