Knife-line attack
Knife-line attack is a narrow, sharp corrosion form along the fusion line in stabilized stainless steels. It occurs due to the dissolution and precipitation of carbides upon severe heating.
Physical-Chemical Mechanism of Action
Knife-line attack occurs when carbides in stabilized stainless steels dissolve and reprecipitate during welding. This happens especially under strong heating and leads to a narrow, knife-sharp corrosion line at the fusion boundary.
Metallurgical Relevance & Risks in Welding
This corrosion can lead to localized strength loss and cracking. It impairs the mechanical properties of the weld and can cause premature failure of the component if not treated properly.
Workshop Practice & Instructions
To avoid knife-line attack, the melting temperatures and times must be precisely controlled for stabilized stainless steels. Excessively high temperature can promote carbide dissolution. Use an optimal shielding gas mixture and ensure careful cooling of the weld.