A characteristic feature is the presence of titanium polymorphic transformation. This leads to significant changes in the structure and mechanical properties of titanium alloys for welding and structural features of the zone of thermal influence of welding process.
welded joint is determined by the presence of two fundamentally different to each other zones - the weld and heat affected. In the area of weld metal is heated to the melting point and some time in the liquid state. At the same time actively develop the processes of saturation of the metal fumes, grain growth, different types of physical, chemical and structural heterogeneity of Education metastable phases, which significantly alters the properties in comparison with the metal to the welding. After crystallization of the metal in the weld zone acquires a characteristic cast structure.
Most of the famous wrought titanium alloys in the cast state has a lower ductility indices. In such cases, to improve the properties of the metal in the weld zone filler materials are used to manage the chemical composition of the weld.
Zone, which determines the weldability of titanium alloys, is a zone of thermal influence. The most dramatic changes in the structure and properties occur in the area directly adjacent to the weld, where there is a fusion of several grains. The metal in this area is heated to a temperature of TPl (the temperature of melting) to ~ 0.9 TPl. This zone is called the weld. Next is the area where the metal undergoes phase recrystallization. When cooling is metastable phases are fixed. The final structure depends on the temperature and cooling conditions. At the boundary of heat affected zone and base metal is part of recrystallization - the site of the gradual transition to the base metal.
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
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