| 摘要 |
The present invention resides in a method for making an internal combustion engine intake valve. An iron aluminum alloy, in the form of a coil or bar stock, is provided. The alloy comprises 76.05 to 90.15 weight percent iron, 9 to 13.3 weight percent aluminum, 0.05 to 0.35 weight percent carbon, and 0.5 to 3 weight percent of a refractory metal, and/or 0.3 to 1.5 weight percent of titanium in combination with, or in place of, the refractory metal. The coil or bar stock is extruded to a poppet valve preform configuration at a heading temperature in the range of 800 DEG to 2,000 DEG F. and a true strain of about 0.5 to 2.2. The preform configuration is then headed to a pre-machined configuration while maintaining the head of such preform at an effective heading temperature up to 2,200 DEG F. said heading being carried out at a true strain of about 1.4 to 2.3. The headed preform is then machined, to its machined configuration, without intermediate heat treatment, and then is coated by either nitriding or chrome plating. If desired, a hardenable steel tip can be welded to the valve stem, and then heat hardened.
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