Whensteelis heated, the surfaceofthe carbonwith the medium(or theatmosphere)of theoxygen, hydrogen,carbon dioxideand water vaporreact, reducing thesurfacecarbonconcentration is calledafterthe decarburization, fromsteelhardeningsurface hardness,fatigue strengthand resistance toreducedwearandsurfaceresidual tensile stressis easy to forma meshsurfacecracks.

Upon heating, thesurface ofthe steelandironand alloyelements andthe medium(orthe atmosphere)ofoxygen, carbon dioxide,water vapor and otherphenomenaoccurin thereaction ofthe oxide filmis calledoxidation.High temperature(generallyabove570degrees), andthe dimensional accuracy ofthe workpiece afterthe oxidationdeterioration ofthe surface brightness,an oxide filmhaving apoorhardenabilityofsteelsprone tohardeningsoft spots.

In order toreduceoxidation anddecarbonizationpreventionmeasuresinclude:surfacecoatings,heatsealedwith astainless steel foilpackaging, usingsalt bathfurnace heating,use of protectiveatmosphere heating(inert gas such aspurified,furnacecarbon potentialcontrol),flame burner(sowasreducingfurnace gas), preferably usinga vacuumfurnace.