Valve Steels   Crucible has been granted patents for valve steels since the mid-1930's. In 1935 Crucible developed the automotive valve steel XCR which dominated the automotive market of the 1930's. While Crucible Industries is longer the leading producer of valve steel bars in North America, billet stock is still available for re-rolling by qualified customers.   Over the years the grades which have been developed by Crucible include: · Age Hardenable Ferritic Valve Steels · Age Hardenable High Silicon Valve Steels · Age Hardenable High Carbon Austenitic Valve Steels · High Chromium, High Heat Resistant Valve Steels · High Manganese Valve Steels · Valve Steels for Severe Duty Exhaust Valves