| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for stably manufacturing a product of a steel wire rod for a valve spring, superior in qualities such as fatigue resistance, which simplifies the steps, has a reduced cost for operating and maintaining the facility, and has high productivity. SOLUTION: This manufacturing method comprises immersing the steel wire rod for the valve spring into the liquid of strong acids selected from nitric acid, nitric-hydrofluoric acid, or sulfuric-hydrofluoric acid, to chemically remove the surface ferrite layer of the above steel wire rods, and then subjecting it to soft annealing, pickling, wire drawing, and further quenching and tempering. COPYRIGHT: (C)2004,JPO
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