Analysis Of Titanium Metal Processing Technology

As a high-performance metal material, titanium exhibits both particularity and complexity in its technological properties.
 

 

Challenge	Core Issues	Solutions
Poor Fluidity	High melting point (1668℃) leads to difficulty filling complex molds; risks of misrun/cold shut.	Adopt vacuum arc remelting/centrifugal casting + high-purity molds; strictly control pouring temperature.
Shrinkage	1.8%-2.5% solidification shrinkage causes stress-induced deformation/cracks.	Reserve larger shrinkage allowances; design uniform wall thickness; conduct stress relief annealing.
Gas Absorption	Gas pores/oxide inclusions degrade mechanical properties and corrosion resistance.	Smelt/pour under vacuum/inert gas (Ar/He) protection; degas raw materials; precisely control pouring speed.
Segregation Tendency	Phase solubility differences of alloying elements + uneven solidification cause regional/grain boundary segregation, leading to inconsistent performance.	Optimize mold cooling systems; control solidification speed; add inoculants; perform homogenization heat treatment post-casting.

 

 

1. Plasticity

At room temperature, pure titanium and titanium alloys have low plasticity with elongation and reduction of area much lower than those of low-carbon steel and pure aluminum. It is easy to fracture. Within a specific high-temperature range, plasticity is improved, allowing them to withstand large deformation.Titanium pressure processing is mostly carried out in a hot state, and processing in the "blue brittle zone" of 200-500℃ should be avoided, otherwise work hardening and cracks are able to occur.

2.Deformation Resistance

Titanium has high strength, and its deformation resistance at high temperatures is still higher than that of low-carbon steel and aluminum alloy. Processing requires large equipment power and causes severe mold wear.It is closely related to processing temperature and deformation speed: increasing temperature can significantly reduce deformation resistance, but it must be controlled below the phase transition temperature; low-speed deformation is more conducive to the plastic flow of titanium and reduces the risk of cracks.

3.Forgability

The method of "small deformation, multiple passes" should be adopted to avoid internal cracks caused by one-time large deformation. After forging, rapid cooling is required to prevent uneven β-phase decomposition. It is suitable for processes,like upsetting, drawing, and punching. Forgings have a dense internal structure and excellent mechanical properties, and are widely used in structural parts in the aerospace field.

4.Rollability

Titanium has the excellent rollability at high temperatures, with a rolling temperature similar to the forging temperature. Continuous hot rolling equipment combined with inert gas protection is required. Pure titanium and low-alloyed titanium alloys have good rollability and can be used to produce plates,sections, pipes, and other products.

 

 

 

5.Extrudability

Titanium's extrudability relies on "high temperature + vacuum/inert gas protection". Pure titanium with good plasticity and α+β type titanium alloy Gr5 are suitable for extrusion processing, and can produce profiles with complex cross-sections. Hot extrusion process is used for extrusion: the mold preheating temperature is about 400-600℃, the extrusion speed is slow , and rapid cooling is performed after extrusion to ensure the dimensional accuracy and uniform structure of the sections.

 

 

1. Weldability

In a broad sense, titanium has good welding joint performance, but strict isolation from air is required. In a narrow sense, titanium has low weld crack sensitivity, but high-alloy titanium alloys are prone to cold cracks. During the welding process, the molten pool and heat-affected zone are prone to reacting with oxygen and nitrogen to form brittle and hard Ti₂O₃ and TiN to decrease toughness of the welded joint. Rapid cooling is prone to forming martensite structure, increasing the hardness and cracking risk of the joint.

2. Weld Formability

Molten titanium has poor fluidity, and weld formation is prone to problems such as uneven width, excessive reinforcement, and rough surface. Welding parameters should be optimized combined with argon protection to ensure uniform and smooth weld formation. Common welding methods include tungsten inert gas welding (TIG) and plasma arc welding. Welding materials should use titanium alloy welding wires matching the base metal composition to avoid composition segregation.

4. Weld Crack Sensitivity

Pure titanium and α-type titanium alloys have extremely low weld crack sensitivity, with the main risk being hot cracks; α+β type and β-type titanium alloys are prone to cold cracks. Control measures include: strict cleaning of the base metal and welding wire surface before welding; preheating before welding; slow cooling after welding, and stress relief annealing to reduce joint stress and hardness.

5. Post-weld Hardening Tendency

Due to structural transformation and solid solution strengthening, titanium alloy welded joints have an obvious post-weld hardening tendency. It has the hardness usually 10%-30% higher than that of the base metal to make subsequent cutting processing more difficult. We need post-weld heat treatment to improve the joint structure, reduce hardness, and enhance toughness and processing performance. Post-weld flaw detection can detect internal defects such as pores and cracks for welding parts with high requirements.

 

Ruihang  mainly manufacture titanium products,such as titanium plates,sheets,bars,wires,tubes,forgings. If you have purchasing needs, feel free to contact us: Sam.Rui@bjrh-titanium.com