| 摘要 |
PURPOSE:To form remelted chilling-treated layer without any bead crack by impressing high density energy on the surface layer of cast iron and removing the locally graphite crystallized part near the surface after chilling by rapidly solidifying the generated melted layer. CONSTITUTION:The high density energy 2 is impressed on at least a part of the cast iron member 1 by high density energy source 4, such as TIG arc, laser, etc., to melt, and in succession, the generated molten layer 3 is rapidly solidified by thermal conducting to the base material side. Then, the above high energy source 4 is reciprocately shifted and is heated so as to increase holding heat in the base material by treating for a somewhat longer time. In this way, the cooling and solidifying velocities in the molten layer 3 near the part of base material are quick, to form the chilled layer 5B. On the other hand, the cooling and solidifying velocities in the surface layer near the central part become slow and graphite is crystallized near the surface in the solidifying process. The solidified layer 5 composed of graphite crystal layer 5A and the chilled layer 5B formed in this way is machined and the above graphite crystal layer 5A is removed, to form the finishing face 6 having good chilled layer 5B surface.
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