Patent ID: 6929566

Claim:
A method of manufacturing a golf club head comprising a face portion, at least part of which is made of a face plate of an alpha and beta type titanium alloy Ti-6Al-4V, the method comprising preparing an ingot of the titanium alloy Ti-6Al-4V formed by melting elements of the titanium alloy and cooling the melted and fused elements so that the ingot has alpha phase crystal structure and beta phase crystal structure and the alpha phase crystal structure is long-grains having an average grain size of not less than 20 but less than 200 micrometers in the longitudinal direction of the long-grain, making a billet of the titanium alloy Ti-6Al-4V by machining the ingot of the titanium alloy, said machining including at least one of cutting, shaving, grinding and polishing, but excluding plastic forming, forging the billet into a face plate within a temperature range of from (the beta transformation temperature −150 degrees C.) to (the beta transformation temperature −20 degrees C.), utilizing mainly compressive plastic deformation caused by a compressive force, so that the average grain size of the long-grains is maintained in a range of not less than 20 but less than 55 micrometers after forged and the long-grain has an aspect ratio of not less than 1.1, but not more than 14.0, and jointing the face plate and a head main body without a heat treatment to the face plate by which the average grain size of the long-grains is changed, whereby the average grain size is maintained within said range of not less than 20 but less than 55 micrometers in the face portion.