Factors affecting titanium tubes

1. Segregation type defects

Except for beta segregation Beta plaques In addition to titanium rich segregation and stripe type A segregation, the most dangerous is the stable segregation of gap type A (type A segregation), which is usually accompanied by small pores around it Cracks containing oxygen Nitrogen and other gases are more brittle. There is also aluminum rich stable segregation (I-type a segregation), which forms dangerous defects due to the presence of cracks and brittleness.

2. Inclusions

Most of them have high melting points High density metal inclusions. High melting point in titanium alloy High density elements are not completely melted into the substrate (such as molybdenum mixture), and are also mixed in smelting raw materials (especially recycled materials), hard alloy tool fragments, or inappropriate electrode welding processes (titanium smelting vacuum consumable electrode remelting method), such as tungsten arc welding, leaving high-density mixtures such as tungsten mixture, titanium removal mixture, etc.

The presence of inclusions can easily lead to titanium rods The occurrence and expansion of cracks in titanium tubes cannot result in defects.

3. Residual shrinkage

4. Holes

Holes exist individually or densely together, which can accelerate the propagation rate of low cycle fatigue cracks and lead to early fatigue damage.

5. Cracks

Mainly refers to forging cracks. Titanium alloy has high viscosity, poor fluidity, and poor heat transfer. Therefore, in the case of forging deformation, due to the high surface friction, the internal deformation is significantly uneven, and the temperature difference between the inside and outside is large, making it easy to get on the titanium rod The cutting band (strain line) is generated inside the titanium tube, which can cause cracking in severe cases, and its direction is generally along the direction of large deformation stress.

6. Overheating

Titanium alloy has poor thermal conductivity. In the case of hot processing, besides improper heating of the titanium rod Under forging conditions, titanium tubes or raw materials are prone to overheating due to thermal effects during deformation, resulting in microstructural changes and the formation of overheated Weibull structures.