X-ray inspection defects of titanium alloy castings Typical defects

The causes of casting defects are various, and the porosity is caused by the sudden change of the solubility of the gas in the titanium liquid when the metal is transformed from liquid to solid, and the failure to escape in time during the solidification process. Shrinkage of the solidified body without the corresponding liquid metal supplement during metal solidification is the most direct cause of shrinkage and shrinkage. When the casting is solidified and contracted, if the internal stress exceeds the strength limit of the material, it may produce hot cracks and cold cracks.

Titanium alloy castings usually improve their internal quality by using hot isostatic pressing technology to remove the defects such as shrinkage and porosity inside the castings. For the near-vacuum cavity casting defects that are not connected with the outside world and within a certain volume range, the change in the volume of the internal cavity defects can be transferred to the surface of the casting by hot isostatic pressing treatment, and the diffusion creep of solid metal under high temperature and high pressure can be used to form a surface depression, which can be eliminated by later grinding, machine adding or repair welding.

At the same time, it should be noted that some defects cannot be eliminated by hot isostatic pressing, which are mainly divided into several categories: first, high-density inclusion and low-density inclusion defects; Secondly, pores, shrinkage holes, porosity and cracks connected with the outside world; Third, the large volume of shrinkage holes and porosity casting defects that are not connected with the outside world. Therefore, before the hot isostatic pressing treatment of titanium alloy castings, X-ray detection is required, and measures of polishing and welding are taken to eliminate excessive defects