Heat Treatment of Welded Joints of Titanium Alloys

In short, the heat treatment.

Heat treatment of welded joints of titanium alloys is carried out in order to relieve internal stresses, optimum physical and mechanical properties and structure of stable (not prone to changes in phase composition and properties during prolonged heating of the Ori operating temperatures). Welded joints, as well as the base metal is subjected to annealing, tempering, quenching and aging (tempering). In this chapter we consider the modes and features of heat treatment of welded joints of titanium alloys of various types. Annealing of welded joints is used for all types of titanium alloys and is the only type of heat treatment for a-, pseudo-a-and p-alloys. This type of heat treatment is performed to relieve internal stresses generated during thermal cycle of welding, as well as to stabilize the structure of the weld in order to obtain optimal properties in the annealed condition and retain their unchanged after prolonged heating at temperatures. Annealing, conducted in a vacuum, along with the decision of the above tasks are used for decontamination of the welded joint of hydrogen. Quenching and tempering, with aging (tempering) is used for alloys with a + p-structure. A hardening of welded joints for practical use does not yet have. Quenching and aging (vacation) is used to increase the strength of the welded joint. In some cases, to increase the strength of using a single aging, because the welds immediately after welding are essentially in the hardened state. When heat-treated titanium, as with other technological operations associated with heating, it is necessary to consider an active interaction with the atmosphere. Oxygen atmosphere not only forms a scale, but also diffuses into the crystal lattice of titanium, dramatically increasing the hardness of the surface layers of metal. This fully applies to the base metal and to weld. At the same time it is considered that heat treatment in furnaces with an air atmosphere at temperatures above 600-650 ° C is admissible and lead to a marked deterioration in the mechanical properties of welded joints and base metal. Heat treatment of welded joints at higher temperatures should generally be carried out in furnaces to protections's atmosphere or in vacuum furnaces. Otherwise, the oxidized layer and polluted gases must be removed by chemical etching or mechanical] way.

See also:
Heat Treatment of Welded Joints of Titanium Alloys
Annealing of Titanium Welded Joints
Hardening Heat Treatment of Titanium Welded Joints
Special Modes of Hardening Heat Treatment of Welded Structures
Effect of Welding on the Structure and Properties of Different Zones of the Welded Joint
Structure and Properties of Heat Affected Zone
Structure and Properties of Welded Joints
Properties and Structure of Welded Joints of Industrial Titanium Alloys
Welding of Titanium