The forming process of corrugated pipe is the process of plastic large deformation of its base material, which makes the structural material (usually austenitic stainless steel) experience the loading and unloading of the plastic range. As a result, the properties of the structural material (mainly the yield strength) are greatly changed, which is the so-called hardening phenomenon. In general, the yield strength of the material increases exponentially after the metal corrugated pipes forming is completed.
Although stainless steel has excellent formability, high fatigue strength, high-temperature strength, and resistance to a variety of corrosion. It is used in large quantities for the manufacture of metal corrugated pipes and has been used successfully. But it has also been found that stress corrosion or crystal corrosion of stainless steel damage problems still exist in large numbers. In order to overcome the above two types of corrosion, there are two common methods: the choice of new high nickel metal corrugated pipes material (such as Incolloy800, Inconel625, etc.) or the metal corrugated pipes after forming solid solution treatment. After the solid solution treatment, the metal corrugated pipes material grain refinement, the organization of a single. It can eliminate the forming stress and improve corrosion resistance. After solid solution treatment, pickling and passivation should be carried out.
1. The initial elastic stiffness of the metal corrugated pipes after solid solution treatment does not change much, but the elastic working range of the metal corrugated pipes is significantly reduced compared with that of the formed metal corrugated pipes. This difference is beneficial to the force situation of the pipe support.
2. The pressure-bearing capacity of the solid solution-treated metal corrugated pipes is significantly reduced, usually only about half of that of the shaped metal corrugated pipes. Therefore, when designing corrugated pipes, it is necessary to increase the thickness of the corrugated pipe, the column stability, and plane stability of the corrugated pipe.
3. The fatigue life of the metal corrugated pipes is less affected by the solid solution treatment, and the fatigue life formula of the formed metal corrugated pipes can be used to calculate the life of the solid solution metal corrugated pipes as long as the reduction of the pressure-bearing capacity of the metal corrugated pipes is fully considered.
4. Solid solution treatment can only eliminate the residual stress generated in the forming process and welding process of the metal corrugated pipes, and cannot eliminate the local stress generated by the deformation of the metal corrugated pipes when absorbing displacement, so the solution treatment cannot be used to eliminate the stress corrosion of the metal corrugated pipes.
Mobile: +86 186 0318 8333