Mfg. steel prods. esp. plates, with high strength and toughness - by selective carburising and quenching specific surface zones of prod.

摘要

A blank is selectively carburised in strip-shaped zones forming a row across the blank or a grid, pref. on both sides of the blank, but not extending through the thickness of the blank. The carburised zones are then hardened, followed by final machining of the blank. The carburised zones pref. possess the same width, and are pref. staggered on the two surfaces of the blank. The carburised zones are pref. locally heated and quenched by rows of burners to form martensite. The blank pref. consists of a carburising steel, but alternatively may consists of a carbon or alloy steel which is selectively decarburised to form low carbon zones between zones of relatively high carbon content. The prods. obtd. have a high strength, but also possess unhardened zones so the prods. have a high toughness.