High-alloy CrNi steels stand out for a high corrosion resistance due to a p
rotective passive layer which forms with the content of chromium exceeding
13 %. When welding these steels, heat tints arise in the area of the welded
joint which may range from faint yellow to intensive blue in the spectrum,
depending on the applied welding process and the backing inert gas. Due to
their structure, they partly drastically reduce the corrosion resistance o
f CrNi steels so that they are a great problem in the technical application
of welded components. In the following contribution the formation and stru
cture of annealing colours is fundamentally described, particularly their i
nfluence on the corrosion depending on the material and the welding technol
ogy.