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US 6,635,128 B1Granted
Work hardened poppet exhaust valve
AssigneeTRW Inc.
InventorsWilliam Neumann, Roger R. Wills, Mohan Kurup, Victor Levin
Life of this patent
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AssigneeTRW Inc.
InventorsWilliam Neumann, Roger R. Wills, Mohan Kurup, Victor Levin
Estimating the term…
A work-hardened poppet exhaust valve for internal combustion engines is obtained from a solutioned work-hardenable austenitic stainless steel coil or bar stock in which chromium is present in the range of 13%-25% by weight, nickel is present in the range of 4%-16% by weight, manganese is present in the range of 0.25%-8% by weight, copper is present in the range of 0.5%-7% by weight, the interstitial elements carbon plus nitrogen are present in a total amount less than 0.45% by nitrogen are present in a total amount less than 0.45% by weight, and at least one refractory metal selected from the group consisting of molybdenum, niobium, vanadium, tungsten and tantalum is present in the range of 1%-5% by weight. The coil or bar stock is extruded to a poppet valve preform configuration at a temperature in the range of room temperature to 1,000° F., and at a true strain of more than 0.8. The parameters of extrusion provide said work-hardened poppet valve with a stem hardness more than Rc=25.
A stainless steel work-hardened poppet exhaust valve having the composition comprising 14-18% by weight chromium, 9-14% by weight nickel, 1-3% by weight manganese, 2-4% by weight copper, 0.09-0.4% by weight interstitial elements, wherein carbon comprises 0.05-0.2% by weight of the composition and nitrogen 0.04-0.2% by weight of the composition, and 3-5% by weight molybdenum, the balance of the composition being essentially iron;
A stainless steel work-hardened poppet exhaust valve made by the process of:
A stainless steel work-hardened poppet exhaust valve having the composition comprising 14-18% by weight chromium, 9-14% by weight nickel, 1-3% by weight manganese, 2-4% by weight copper, 0.09-0.4% by weight interstitial elements, wherein carbon comprises 0.05-0.2% by weight of the composition and nitrogen 0.04-0.2% by weight of the composition, and 3-5% by weight molybdenum, the balance of the composition being essentially iron, said work-hardened poppet exhaust valve having a stem hardness more than Rc=31, the amount of molybdenum being sufficient to precipitate Fe2Mo intragranularly when said exhaust valve is placed in service in an internal combustion engine.
Dependencies are inferred from the claim text.