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Titanium ASTM Grade
What is Titanium ASTM B381 Gr 12
Titanium ASTM B381 Grade 12 can also be named as Titanium Grade 12 or Ti-0.3Mo-0.8Ni. For this grade, small percentages of molybdenum at 0.3% and nickel at 0.8% are alloyed to provide higher strength and superior corrosion than commercially pure titanium in various applications at extreme conditions. Corrosion Resistance: This grade of 12 titanium has excellent corrosion resistance and is particularly useful for applications that endure reducing acids, chlorides, or other chemicals. This grade makes the alloy applicable in chemical processing, marine environment, and heat exchanger applications.
Strength: Grade 12 has greater strength than the pure grades of titanium, which enables higher resistance to mechanical stress.
Weld Ability: The weld ability is the same as with other titanium alloys and excellent for effective fabrication with any of the processes mentioned for TIG and MIG welding.
Chemical Processing: Structures consisting of heat exchangers, reactors, and tanks.
Marine: In seawater applications due to its resistance to saltwater corrosion.
Aerospace: For some parts that have to withstand strength-to-weight ratio and corrosion requirements.
Definition of Titanium ASTM B381 Grade 12
Titanium ASTM B381 Grade 12 alloy is essentially titanium alloy made primarily of titanium (Ti) with 0.3% molybdenum (Mo) and 0.8% nickel (Ni). This alloy has been designed to enhance corrosion resistance and strength of titanium further to make it suitable for even the most demanding environments, where resistance against corrosion and good mechanical properties, in particular high strength and ductility are essential.
Titanium (Ti): The basic base material with excellent strength-to-weight ratio, very good corrosion resistance, and low density.
Molybdenum (Mo): Strengthens resistance to reducing acids; strength is raised.
Nickel (Ni): It provides good all-round corrosion resistance, particularly to acids and chlorides.
Applications:
The following industries have titanium ASTM B381 Grade 12 that is pure within:
Chemical Processing: For heat exchangers, reactors, and any equipment exposed to corrosive chemicals.
Marine Uses: It boasts of excellent resistance to corrosion from sea water and salt. Aerospace: Where strength, low weight, and corrosion resistance are essential for critical components.
Welding Properties of Titanium ASTM B381 Grade 12
Titanium ASTM B381 Grade 12 is a weldable alloy of titanium, molybdenum and nickel alloy. Commonly it is used for applications based on high strength corrosion resistant welds. However, as titanium, being an inherently reactive substance, welding of this grade particularly requires caution not to let the welds suffer from degradation owing to oxidation, porosity, or embrittlement.
Weld Ability:
Grade 12 Titanium: Similar to all the titanium alloy, it possesses good weld ability. It can be welded by common methods TIG, MIG, and submerged arc welding. The overall weld ability along with resistance to cracking is enhanced by the molybdenum and nickel alloys.
Pre-Weld Preparation:
Cleaning: Titanium alloys, including Titanium Grade 12, are reactive with oxygen, nitrogen, and hydrogen at high temperatures. Thus, surface cleaning of the product before welding becomes essential. Use abrasive or solvent-based cleaners to remove oils, oxides, and other contaminants from the surfaces.
Edge Preparation: The edge preparation should ensure adequate strength of weld. Thus, the joint design should not have high stress concentrations.
Shielding Gas:
Inert Gas: Argon is normally used in the shield of welding titanium, though often contaminated with or lacking a significant chance of oxidation. Helium can be blended in with argon for increased penetration.
The shielding gas should be applied both during the welding process and in order to back-purge the root of the weld to prevent oxidation on the underside. Input Heat Control The most critical feature of titanium welding is that the heat input must control. High heat input causes distortion, embrittlement, and cracking in the weld area. Thus, low heat input and high welding speed must ensure in order to minimize the heat input to the base material.
Post-Weld Treatment:
This Grade 12 titanium, generally speaking, does not require post weld heat treatment; but, it can be used when residual stresses in the material need to be relieved and its properties enhanced. The weld may be protected from oxidation on the inside by using argon or helium for back purging to keep one surface of the weld and the other surface under inert atmosphere.
Chemical Composition
| Element | Nickel, Ni | Iron, Fe | Molybdenum, Mo | Oxygen, O | Carbon, C | Nitrogen, N | Hydrogen, H | Titanium, Ti |
|---|---|---|---|---|---|---|---|---|
| Content (%) | 0.6 – 0.9 | 0.3 max | 0.2 – 0.4 | 0.25 max | 0.08 max | 0.03 max | 0.015 max | Remainder |
Conclusion of Titanium ASTM B381 Grade 12
Titanium alloy, ASTM B381 Grade 12, combines the exclusive properties of titanium resistance to corrosion with strength-improving properties of molybdenum and nickel. Consequently, it is especially applicable for chemical processing, marine, and aerospace, conditions in which materials are exposed to aggressive environments and require simultaneous strength and endurance.
Grade 12 titanium welds well but is reactive therefore, precautions are necessary when welding it. Such precautions include preparation before welding, shielding during welding, and proper heat input to eliminate the possibility of oxidation, embrittlement, or cracking in weldments. When this is done, Grade 12 titanium can be welded into strong, reliable components that retain the inherent corrosion resistance and mechanical properties of the base material.