Steam annealing (also oxidize or vaporize ) is a thermochemical process for tool machining.
By the treatment in pure water vapor atmosphere at about 520 580 ° C where water to hydrogen and oxygen dissociated , an approximately 10 micron thick, dark blue-gray matte black layer is formed on the workpiece iron (II, III) oxide (of course as magnetite occurring ). In addition to the visual effect, steam tempering improves corrosion resistance , increases surface hardness and minimizes the coefficient of friction . The process is primarily used for ferrous materials; Tools treated in this way are only suitable for machining these materials. Often the workpieces are also nitrided .
- Eberhard Paucksch, Sven Holsten, Marco Linß, Franz Tikal: Machining technology: processes, tools, technologies . 12th edition. Vieweg + Teubner , Wiesbaden 2008, ISBN 978-3-8348-0279-8 , pp. 69-71 .
- Stephan Hasse: Foundry Lexicon . 19th edition. Schiele & Schön , Berlin 2007, ISBN 978-3-7949-0753-3 , pp. 206-207 .