Prevent intergranular stress corrosion cracking method

As intergranular stress corrosion cracking is probably caused because of the chromium depleted zone, preventing intergranular stress corrosion cracking method may include post-weld heat treatment to restore the diffusion of chromium, the carbon content to very low levels and adding titanium to inhibit precipitation of chromium carbide.

To determine the impact of post-weld heat treatment, the carbon material of 100ppm two passes through a heating cycle sensitization, followed by the different conditions in the third pass of the heating cycle. Similar to the above using U -bend stress-corrosion cracking test to evaluate the samples prepared. The results showed that the range of 550 ~ 700 ℃ heated few minutes, sensitized specimens crack. This effect may be due to the heat treatment to increase the diffusion of chromium, thus narrowing the chromium depleted zone. PWHT using short (a few minutes), you can prevent intergranular stress corrosion cracking, which is the actual laying of pipeline efficiency without hinder.

To determine the lower carbon content, and adding titanium influence on different carbon content and the titanium content of the material was evaluated. The samples were 450 ℃, 1000s a heating cycle of treatment, this condition is likely to cause sensitization, a similar U-shaped pattern bending stress corrosion cracking tests. With the change of test conditions, the U-shaped bend in the sample by generating a gap. The results show that addition of titanium to reduce carbon content and inhibit the generation of cracks. This is probably because the soldering is suppressed and the dissolution of carbon into titanium carbide and chromium depleted suppressed cause precipitation of chromium carbides. Therefore, reducing the carbon content and the addition of titanium to improve the material resistance to intergranular stress corrosion cracking an effective manner.