SURFACE HARDENING OF GRAY CAST IRON FOR AUTOMOTIVE CYLINDER BLOCK USING HIGH ENERGY ELECTRON BEAM IRRADIATION

摘要

PURPOSE: A method for hardening the surface of gray cast iron material used for engine block material by projecting electron beam with a specified amount of projection energy density is provided, which can conduct operations in atmospheres, improves productivity and prevents oxidation of material surface. CONSTITUTION: A high voltage accelerated electron beam is projected with an amount of projection energy density of 1.2 to 2.1KW/cm¬2 to the surface of gray cast iron material used for engine block material comprising at least one component selected from the group consisting of 2.0 to 4.0% by weight of C, 1.0 to 3.0% by weight of Si, 1.0% or less by weight of Mn, Cr, Cu, P and S; and the balance of Fe to form a surface hardening layer having a Vickers hardness of 600 to 850 VHN and comprising martensite.