Austenitic steels

You can share such steels into three main groups:

• normal austenitic steels, non-stabilized, with increased carbon content, heat resistant;
•     stabilized austenitic steels;
•     austenitic steels with low carbon content.

Resolution capability

It heats the steel with a sufficiently high temperature so that the native of processing methods strukturalische change can be eliminated; With this method, the material remains in a certain temperature, which (especially the chromium carbides) to connect all carbides with the solution, as well as the cooling procedure must be slow enough to keep the carbide precipitates (450 and 850 ° C takes place between) to avoid. Thus, the steel is in the maximum Erweichungslage. Three factors play an important role, namely the temperature (about 1000-1100º C), speed of treatment (depending on the thickness of the material) and the speed of cooling. At such a temperature a recarburising on the surface is very likely, for austenitic steels, which means that the risk of carbide precipitation is quite large (one must also consider whether the atmosphere is not carburized in the oven). The cooling must be done quickly. By recrystallization annealing with high temperatures to obtain a larger grain dimension; by the corrosion can be even harder.

· Sensitization to intergranular corrosion

One method that is used only in the laboratory to determine the sensitivity to intergranular corrosion. For steels selected from the groups "normal austenitic steel" is carried out at a temperature between 450 and 850 ° C a Chromkarbidausscheidung, with corresponding thereto reduction of the chromium content, and therefore a higher probability of IK-corrosion. In order to avoid such a problem, one uses stabilized elements, such. As titanium, and niobium, the easier combine with carbon than with chromium. Thus, the depletion of free chromium in the alloy is avoided and therefore it prevents the sensitization of the steel (in this case, is the awareness between 1250-1300º C).

· Relaxation

Thus, the internal tensions arising from the production process are eliminated. For spring band steels (extremely hard material), the breaking load is made larger by an expansion to increase the elastic properties, with a heat treatment under 450 ° C (temperature of Sensibilisierungshärtbargkeit). Since the material thickness is a few tenths of a millimeter is the time of heat treatment is very short (a few seconds). The relaxation is complicated for welded materials. Must To beiseitigen voltages for such materials to anneal the material, then there is cools at the welded places the risk of "stress corrosion".