| abstract |
An upset-forged poppet valve wherein at least the head portion and a part of the neck is made of a high temperature super alloy while the remaining portion is made of a conventional valve steel, said two materials being connected by friction welding before said valve is forged. The method comprises two steps of first friction-welding two rods of said two materials and then forming the connected single rod into the poppet valve by upset-forging. |