Graphitization

Graphitization means the carbon in the steel no longer binds in the structure, but precipitates as free graphite. This mainly happens in high-carbon steels, and silicon promotes it further. The structure becomes soft and brittle, the weld loses strength and can crack under load. When welding such material, you must control heat input and cooling. Too slow cooling in critical areas promotes graphite precipitation. Pay attention to proper preparation and keep the weld clean, then you usually keep the problem under control.