SURFACE HARDENING METHOD OF CAST IRON MATERIAL

摘要

PURPOSE:To form inexpensively mixed structure of cementite and martensite to the specific surface part of a cast iron material without blowholding by coating the surface of said material to be subjected to a surface hardening treatment with Al and subjecting said surface in this state to the surface hardening treatment by remelting. CONSTITUTION:The surface of a cast iron material is coated with Al and said surface is melted by a high energy source then the molten part is quickly cooled. The Al which shifts the Ms point to a high temp. side is incorporated into the melt of the cast iron material in the stage of melting the surface of said material and the molten part is quickly cooled in this state according to the above- mentioned method. The mixed structure of cementite and martensite can be thus formed on the specific surface of an ordinary cast iron which does not contain Cr, etc. for improving quench hardening power. The oxygen contg, in this material and the oxygen intruded from the atmosphere combine preferentially with the Al to suppress blowholing.