THE RELATION OF THE PRECIPITATION PROCESSES TO THE PROPERTIES OF CORROSION-RESISTANT STEELS (VZTAH PRECIPITACNICH PROCESU K VLASTNOSTEM KOROZIVZDORNYCH OCELI)
Abstract
The authors trace the structural changes in stabilized stainless steels with respect to selective types of corrosion. Main consideration is given to delta ferrite and its decomposition in 1Cr18Ni9Ti steel. The electron microscope was used to advantage in the study of changes taking place in ferrite. Apart from the carbide precipitation, which initiates the ferrite decomposition, two phases, sigma and austenite, form from delta ferrite. The sigma phase in stabilized steels starts with the formation of lamellae at the grain boundaries between austenite and ferrite and spreads gradually inside the delta ferrite grains. The local change in chemical composition during the ferrite decomposition is one of the main causes of increased attack in the given type of steel in the transpassive state. The selective attack on welded joints in these steels (at the weld junction) is closely associated with these structural changes and shows up especially well during treatment with hot concentrated nitric acid.
Document Details
- Document Type
- Technical Report
- Publication Date
- Nov 08, 1967
- Accession Number
- AD0670100
Entities
People
- O. Vanicek
- V. Cihal
Organizations
- National Air and Space Intelligence Center