We have developed a case hardening steel for coldforging which does not require annealing or normalizing process.Silicon and manganese contents of developed steel are made lessthan conventional steels to reduce the hardness after hot rolling.Boron is added to increase the hardenability and niobium is addedto prevent the abnormal grain growth. The hot rolled hardness ofdeveloped new case hardening steel is equivalent to thespheroidizing-annealed conventional steel. The steel can be heatedto higher temperature without grain coarsening than theconventional steels, and it can be Carburized after cold forgingwithout normalizing.
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