A method for qualitaet improvement of steel profiles

摘要

The elastic limit and breaking load of steel sections are improved by a process of surface hardening and self-tempering comprising a cooling stage which converts the surface region to austenite and ferrite. This is followed by a rapid hardening cooling which converts that austenite to martensite/bauxite and is interrupted to allow the surface layer of the section to be tempered by non-hardened inner portions of the section. The rapid cooling is succeeded by a slow cooling, whereby core austenite transforms to ferrite and carbide.