Baumann imprint
A Baumann imprint is a method for detecting sulfur and its distribution in steel . The method is used to detect areas with a high concentration of sulfur. The sulfur concentrations arise from segregation processes when the steel cools, so-called block segregation .
execution
To test the steel, photo or bromide silver paper soaked in dilute sulfuric or hydrochloric acid is pressed onto a sanded surface of the test object. Depending on the type of steel , the contact time is around 30 seconds to several minutes. The reaction of the acid with the sulfides contained in the metal piece creates hydrogen sulfide , which reacts to black silver sulfide in the silver layer of the test paper . The silver sulfide causes a more or less strong (brown) coloration of the photo paper. After a fixation like in photography, this image can be used for documentation. This enables comparisons and evaluations of the steel quality.
literature
- Ulrich Dilthey: Welding production processes. Volume 2: Behavior of the materials during welding. 3rd edited edition. Springer-Verlag, Berlin et al. 2005, ISBN 3-540-21674-X ( study and practice ).
- Stephan Hasse, Ernst Brunhuber (Ed.): Giesserei Lexikon. 18th edition. Fachverlag Schiele & Schoen, Berlin 2001, ISBN 3-7949-0655-1 .