Low hydrogen annealing
Low- hydrogen annealing is a partial process of the heat treatment of steels , which serves to reduce or eliminate hydrogen embrittlement in steel components.
With low hydrogen annealing, the workpieces are kept at temperatures between 200 ° C and 300 ° C for several hours. In this case, the escape in the structure embedded hydrogen - atoms which make the material brittle, by effusion from the components.
Low-hydrogen annealing is mainly carried out immediately after the components have been welded or galvanized .
This process is also called tempering or tempering . Galvanized parts should usually not be tempered above 220 ° C, as otherwise the zinc layer, which is important for corrosion protection, will get cracks and flaws of several micrometers and the corrosion protection will no longer be adequate. Hydrogen is the smallest atom, which is why it has a high diffusion speed even at low temperatures . It is possible to drive the hydrogen out of the steel at temperatures of up to 300 ° C without changing it metallurgically.