Chemical Composition & Material Specifications

CP Titanium Grade 2 meets ASTM B265 (Sheet, Strip, Plate), ASTM B348 (Bar, Billet), ASTM F67 (Unalloyed Ti for Surgical Implants), AMS 4902, AMS 4941, AMS 4942, and other international standards. The precise control of interstitial elements—carbon, nitrogen, and oxygen—combined with limited iron content ensures excellent corrosion resistance and biocompatibility.

Physical & Mechanical Properties

Physical Properties

CP Titanium Grade 2 is a hexagonal close-packed (hcp) alpha-phase single metal at service temperature. Pure titanium undergoes an allotropic transformation from the hexagonal close-packed alpha phase to the body-centered cubic beta phase at 882.5°C (1620.5°F). The material exhibits excellent physical properties supporting its use in demanding applications:

Mechanical Properties

CP Titanium Grade 2 exhibits moderate strength with excellent ductility. Mechanical properties can be controlled through heat treatment (annealing and stress relief) and grain size management. The material work-hardens relatively rapidly, a limitation in cold-forming operations but providing strength advantages in as-formed conditions. Due to low modulus of titanium, springback allowances are significant. Hot sizing after cold forming is often used to correct for springback variations.

Heat Treatment & Processing Characteristics

Heat Treatment Options

CP Titanium Grade 2 can be processed using annealing and stress-relief heat treatments. Annealing at temperatures below the beta transus (1610–1660°F) produces fully recrystallized equiaxed alpha structure. Precise grain size control and mechanical property optimization can be achieved by adjusting anneal temperature. Stress relieving removes residual stresses from forming or recovers compressive yield strength after stretching.

Critical Processing Considerations

Titanium and its alloys have a high affinity for gases including oxygen, nitrogen, and hydrogen. When CP Ti is heated in air, oxygen absorption results in the formation of an extremely hard, brittle, oxygen-stabilized alpha phase layer known as alpha case. Intermediate and final annealing of CP Ti must be performed in vacuum or inert gas atmosphere to avoid alpha case formation and associated material loss. Vacuum annealing can also remove excess hydrogen pickup through a process known as vacuum degassing.

Machining Characteristics

CP Titanium Grade 2 exhibits machining characteristics similar to austenitic stainless steels. General recommendations include low cutting speeds, heavy feed rates, and copious amounts of cutting fluid. Sharp tools and rigid setups are critical. Because of titanium’s strong tendency to gall and smear, feeding should never be stopped while tool and workpiece are in moving contact. Non-chlorinated cutting fluids are essential to eliminate chloride-induced stress-corrosion cracking. Titanium chips are highly combustible; appropriate safety precautions are necessary.

Weldability

CP Titanium Grade 2 can be welded using CP Titanium filler metal. Inert gas shielding techniques must be employed to prevent oxygen pickup and embrittlement in weld areas. Gas tungsten arc welding is the most common process. GMAW is used for thick sections. Plasma arc, spot, electron beam, laser beam, resistance, and diffusion welding have all been successfully employed.

Corrosion Resistance in Marine & Chemical Environments

CP Titanium Grade 2 is highly resistant to general corrosion in a wide variety of environments. The material’s corrosion resistance is based on the presence of a stable, continuous, tightly adherent oxide film that forms spontaneously upon exposure to oxygen in air or water. If damaged, the oxide film re-forms readily as long as oxygen (from air or moisture) is available in the environment. In general, the higher the purity of CP Ti, the greater the corrosion resistance. CP Grade 2, with its relatively low impurity levels, is capable of performing well in many corrosion-critical applications including marine environments and chemical processing.

Seawater Performance & Chemical Resistance

CP Grade 2 is fully resistant to corrosion in seawater at temperatures up to 315°C (600°F), though crevice corrosion must be considered and components appropriately designed to avoid tight crevices. The material is highly resistant to oxidizing media, alkaline media, organic compounds and acids, aqueous salt solutions, and wet or dry hot gases. It has sufficient corrosion resistance in liquid metals, nitric acid, mildly reducing acids, and wet chlorine or bromine gas (with minimal oxygen or water present).

Stress-Corrosion Cracking & Hydrogen Embrittlement

CP Grade 2 is fully resistant to stress-corrosion cracking in aqueous solutions and is largely immune to SCC in general. The material is susceptible to hydrogen embrittlement due to hydride formation. Specifications typically limit hydrogen to 150 ppm maximum, but degradation can occur at lower levels, especially with notches. Minimize hydrogen pickup during processing, particularly during heat treating and acid pickling. Avoid chlorinated compounds during processing.

Markets & Applications for CP Titanium Grade 2

Additive Manufacturing Process Guidance

Equipment Compatibility & Processing

CP Titanium Grade 2 is compatible with commercial L-PBF and EB-PBF equipment designed for titanium powder processing. The material requires careful parameter optimization for each specific equipment platform and geometry to achieve optimal density and mechanical properties.

Heat Treatment & Cleaning Requirements

CP Titanium undergoes allotropic transformation at 882.5°C (1620.5°F) from hcp alpha phase to bcc beta phase. Following heat treatment in air, completely remove surface scale and underlying brittle alpha case layer. This can be accomplished by mechanical methods (grinding, machining) or by descaling followed by pickling in nitric/hydrofluoric acid mixture. Exercise caution to avoid excessive hydrogen pickup.

Cleaning & Preparation

Parts to be vacuum heat treated must be thoroughly cleaned. Oils, fingerprints, or residues can result in alpha case formation even in vacuum atmosphere. Recommended cleaning procedure:

• Thorough cleaning using non-chlorinated solvent or aqueous solution
• Rinsing with copious quantities of deionized or distilled water
• Drying completely before handling
• Handling with clean gloves to prevent recontamination

Critical Safety & Processing Notes

Avoid chlorinated compounds during all processing. Chlorides in some cleaning agents have been associated with stress-corrosion cracking of titanium. Final heat treatments on finished parts should be performed in vacuum if machining or pickling is to be avoided, ensuring maximum corrosion resistance and mechanical properties.