1. Parsed defects
in addition to \946; segregation,\946; spot, titanium-rich segregation and strip-like α segregation, the most dangerous one is interstitial α-stable segregation (type i α-segregation), which is often accompanied by small holes, cracks, containing oxygen, nitrogen and other gases, with greater brittleness. There are also aluminum-rich α-stabilized segregation (type II α-strangement), which is also a dangerous defect due to the presence of cracks and brittleness.
2. Inclusions
be mostly high melting point, high density metal inclusions. There are also high-density inclusions, such as tungsten inclusions and titanium inclusions, which are left behind by high melting points and high-density elements that are not fully melted in the matrix (e.g. molybdenum inclusions) in titanium alloy components, as well as carbide tool caving or improper electrode welding processes (titanium alloy smelting is generally done by vacuum self-consuming electrode remelting) mixed in smelting raw materials (especially recycled materials).
The presence of inclusions tends to lead to crack occurrence and expansion and is therefore a non-permissive defect (e.g. the Soviet 1977 data stipulated that high-density inclusions with diameters of 0.3 to 0.5 mm had to be recorded during the X-ray examination of titanium alloys).
3. Residual shrinkage
4. Holes
Holes are not necessarily single and may have multiple dense presences, which will accelerate the growth of low cycle fatigue cracks and cause early fatigue damage.
5. Cracks
mainly refers to forging cracks. The viscosity of titanium alloy is large, the fluidity is poor, and the thermal conductivity is not good, so in the process of forging deformation, because of the large surface friction force, the internal deformation inhomogeneity and the large temperature difference between inside and outside, it is easy to produce shear band (strain line) inside the forging, which leads to cracking when it is serious, and its orientation is generally along the direction of maximum deformation stress.
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