What Is Titanium Grade 12
Titanium Grade 12, UNS R53400, is an alpha titanium alloy containing about 0.3 percent molybdenum and 0.8 percent nickel. The additions are small, but they change the electrochemical behaviour of the material and markedly improve its resistance to reducing and mildly oxidizing environments. Grade 12 is frequently selected where commercially pure grades suffer crevice corrosion or attack by hot chloride solutions and dilute reducing acids.
Composition and Microstructure
The nominal composition of Grade 12 is titanium with molybdenum 0.2 to 0.4 percent, nickel 0.6 to 0.9 percent and iron up to 0.3 percent, with oxygen limited to 0.25 percent maximum. The molybdenum and nickel remain largely in solid solution and help stabilize the passive film, while the alloy retains the single-phase alpha microstructure typical of pure titanium. The material is weldable using standard titanium practice with argon shielding.
Mechanical Properties
Grade 12 offers roughly 40 percent higher minimum tensile strength than Grade 2. The ASTM specification requires a minimum ultimate tensile strength of 483 MPa and a minimum yield strength of 345 MPa with at least 18 percent elongation in bar, pipe and tube products. The alloy keeps useful strength at elevated temperature, which extends its application range in heat exchange equipment.
Minimum tensile strength 483 MPa.
Minimum yield strength 345 MPa.
Minimum elongation 18 percent.
Density approximately 4.51 g per cubic centimetre.
Corrosion Resistance
The molybdenum-nickel addition suppresses the cathodic reaction and raises the corrosion potential, so Grade 12 resists attack in hot brines, seawater and dilute sulfuric and hydrochloric acids where CP grades pit or crevice corrode. It performs well in both oxidizing and reducing media and is a common choice for shell-and-tube exchangers, brine heaters and process piping in chemical plants.
Applications
Heat exchangers and condensers in chloride service.
Brine heating and seawater handling systems.
Process piping for dilute acid streams.
Pump casings, valves and fittings in chemical plant.
Geothermal and marine energy equipment.
Standards and Supply Forms
Grade 12 is covered by ASTM B861 for pipe, ASTM B862 for welded pipe, ASTM B338 for heat exchanger tubing, ASTM B348 for bar and billet and ASTM B265 for sheet and strip, with ASME counterparts such as SB861 and SB338. Material is supplied with mill test certificates reporting heat number, composition and mechanical results against the ordered specification.
Frequently Asked Questions
Q: Is Grade 12 a commercially pure titanium grade?
A: No. Grade 12 is an alloy grade containing molybdenum and nickel, although it is sometimes grouped with CP grades in simple price lists.
Q: What is the UNS number of Grade 12?
A: The UNS designation is R53400, and the nominal composition is titanium with 0.3 percent molybdenum and 0.8 percent nickel.
Q: Where does Grade 12 outperform CP grades?
A: In reducing acids, hot brines and chloride solutions where commercially pure grades suffer crevice corrosion or pitting attack.
Q: What strength does Grade 12 offer?
A: Minimum tensile strength of 483 MPa and minimum yield strength of 345 MPa with 18 percent elongation under the ASTM specifications.
Q: Which standards cover Grade 12?
A: ASTM B861, B862, B338, B348 and B265 with ASME counterparts such as SB861 and SB338, depending on the product form.
Q: Can Grade 12 be welded?
A: Yes, it is weldable with standard titanium welding practice using argon shielding and clean surface preparation.
