Polished Seamless Titanium Pipe Stainless Steel Tubing High Toughness Stress Corrosion

Titanium Grade 12 Seamless Titanium Pipe Polished Stainless Steel Tubing

Spezilla supplies welded and seamless titanium tubing in variety of sizes, standard/off-the-shelf or tailored to meet the customers’ unique requirements. If required, we can provide value-added services such as export boxing and U-bending.

Lightweight, high strength and corrosion resistant, titanium is the material of choice in industries ranging from chemical process to power generation.

Description

Titanium Grade 12 is a highly 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.

Fabrication

Titanium Grade 12 is forged conventionally, within the narrow temperature range 815 – 900°C. Titanium and its 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

Titanium 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

Titanium 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 beCLEAN, 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

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.

Chemical Composition:

Specified Minium Mechanical Properties:

Specifications: