CYLINDER COVER AND METHOD OF IMPROVING CORROSION RESISTANCE THEREOF

Provided is a method of improving corrosion resistance of a cylinder cover (1) including a port (11) that is an intake port or an exhaust port. The cylinder cover (1) is configured such that an annular cooling water passage (4) is formed between an inner peripheral surface (12) of the port (11) and a valve seat ring (3) when the valve seat ring (3) is inserted in the port (11). The method includes forming a weld overlay layer (7) on each of sealed regions (13, 15) of the inner peripheral surface (12) of the port (11) by laser metal deposition using a welding material made of a nickel-based alloy, a copper alloy, stainless steel, or a titanium alloy, the sealed regions (13, 15) being positioned at both sides of the cooling water passage (4), respectively.