Titanium alloy grade 12 is a high corrosion resistant alloy containing small additions of nickel and molybdenum, which enhance corrosion resistance and increase the strength of the alloy to give better mechanical properties than the commercially pure grades. It is used in mildly reducing or fluctuating conditions. In particular, it is used instead of the commercial purity grades (e.g.grade 2) for better resistance to crevice corrosion in hot brines, and where the extra strength allows the use of lighter sections. At room temperature, it is an alpha alloy and may contain minor amounts of beta phase. It transforms to beta phase at 890°C ± 15°C. Titanium is reactive, and has a very high affinity for oxygen, which forms a skin of very stable and highly adherent oxide. The skin gives excellent corrosion resistance, despite the reactivity of the metal. The oxide layer forms spontaneously and on exposure to the atmosphere. However, when new parent metal is exposed to anhydrous conditions or in the absence of air, rapid corrosion may occur. Care should also be taken if titanium is to operate in contact with hydrogen, as hydrogen embrittlement from hydride formation can increase strength, with loss of ductility.
Equivalent Gradesof of Titanium Grade 12 (UNS R53400)
Titanium Grade 12
Chemical Composition of Titanium Grade 12 (UNS R53400)
Titanium Grade 1
Titanium Grade 2
Titanium Grade 4
Titanium Grade 5
Titanium Grade 7
Titanium Grade 9
Titanium Grade 12
Mechanical Properties of Titanium Grade 12 (UNS R53400)
ASTM Specifications of Titanium Grade 12 (UNS R53400)
ASME B861 (Grade 12)*
ASME B862 (Grade 12)*
Titanium and Titanium Alloy Forgings
Titanium and Titanium Alloy Bars and Billets
ASTM B265 (Grade 12)
Titanium and Titanium Alloy Strip, Sheet & Plate
Seamless and Welded Titanium and Titanium Alloy Tubes for Condensers and Heat Exchangers
ASTM B348 (Grade 12)
Bars and Billets
ASTM B337 (Grade 12)
Welded and Seamless Pipe
ASTM B381 (Grade 12)
AWS A5.16 (ERTi-12)
* Replacing ASTM B337 (Seamless and Welded Titanium and Titanium Alloy Pipe)
In what applications is Titanium Grade 12 (UNS R53400) used?
Titanium Grade 12 Pipes and Tubing are extensively applied in extremely corrosive conditions in the below Industries.
Oil & Gas Industry
Paper & Pulp Industry
Food Processing Industry
Corrosion Resistance of Titanium alloy grade 12
Titanium alloys are usually used in Australia for their excellent corrosion resistance, especially to chloride solutions. The small additions of nickel and molybdenum to grade 12 titanium give a more corrosion resistant metal than the commercial purity grade 2 alloy, with a marked increase in strength. The overall corrosion resistance of this grade is not as good as the palladium alloyed lean grade 7, except for resistance to crevice corrosion in hot chloride solutions. Titanium has excellent resistance to general corrosion, with loss rates of less than 0.04mm/year being typical.
Fabrication with Titanium alloy grade 12
Titanium alloy grade 12 is forged conventionally, within the narrow temperature range 815 – 900°C. Titanium and titanium alloys are generally more difficult to forge than both aluminium and alloy steels, due to their high strain rate sensitivity and rapid increase of strength with falling temperature. Hot forging leaves a thick, hard outer layer of titanium oxide on the surface. This layer is called “Alpha Case” and is usually removed by pickling in a mixture of nitric and hydrofluoric acids. As supplied, titanium alloys are usually annealed and pickled, and can be readily cold formed in conventional machines using standard methods. In cold forming the “alpha case” does not form and further pickling is not needed, except to remove any carbon steel embedded in the surface, which can cause pitting corrosion.
Machinability of Titanium Grade 12 (UNS R53400)
Titanium alloy grade 12 is readily machinable by conventional methods. Like stainless steel, titanium has a low thermal conductivity and heat dissipation is inhibited, so copious amounts of coolant should be used. Sharp carbide tools are used. Deep, continuous cuts are best.
Weldability of Titanium Grade 12 (UNS R53400)
Titanium alloy grade 12 is readily weldable by GMAW (MIG) and GTAW (TIG) processes. Preheat or post weld heat treatment are not needed. The area to be welded must be CLEAN, free from all grease and shop dirt, including marking pencil marks. A trailing gas shield is used in addition to the normal welding torch gas shield, to prevent heavy oxidation during cooling. Matching filler metal to AWS specification ERTi-12 is used. The gas shield must be low in hydrogen, oxygen and nitrogen, all of which readily dissolve in titanium and cause embrittlement.
Heat Treatment of Titanium Grade 12 (UNS R53400)
Titanium Grade 12 is normally supplied in the annealed condition. After fabrication, stress relief at 480 – 595°C, air cooled, may be required to improve dimensional stability.
O.D. , W.T & Length Range:
Cold Reduced Tubing (lengths up to 708″/18000mm)
0.118″ – 4.5″
3 mm – 114.3 mm
0.020″ – 0.433″
0.5 mm – 11 mm
Hot Rolled Pipe (lengths up to 157″/4000 mm)
2.756″ – 3.937″
70 mm – 100 mm
0.354″ – 1.181″
9 mm – 30 mm
Hot Extruded Pipe (lengths up to 240″/6096 mm)
1.968″ – 6.625″
50 mm – 168 mm
0.276″ – 1.378″
7 mm – 35 mm
Wall thickness (ASME B36.10 & B36.19) of titanium pipe