High fatigue-strength steel wire and spring, and processes for producing these

The present invention relates to a steel wire and spring having superior fatigue properties and to a method of manufacturing such a steel wire and spring. A steel wire of pearlite structure containing 0.8-1.0 mass % of C and 0.8-1.5 mass % of Si is disclosed. In the cross section of the steel wire the average hardness in a region up to 100 m from the surface thereof is at least 50 higher that that in a deeper region based on micro-Vickers hardness. The steel wire is manufactured by working a wire rod having the abovementioned chemical composition through shaving, patenting and drawing processes, then strain-relief annealing the resultant wire, and thereafter subjecting the thus annealed wire to a short peening process. The steel wire can be produced through a drawing process without applying a quenching and tempering process, and are superior in heat resistance and fatigue strength.