Patent ID: 7429301
Filing Date: 2008-09-30
Classification: C22C,Y10S

Abstract:
1. An ultra clean spring steel provided in the form of a wire, wherein: the wire comprises oxide inclusions with a sulfur concentration no more than 10 mass %; no less than 70% of the inclusions, in terms of numbers, that exist in an outer layer outside one quarter of a diameter of the wire and have a width no smaller than 3 μm, satisfy formula (1) and satisfy two or three of formulae (A) to (C) the width of an inclusion is a diameter of the inclusion measured in a direction perpendicular to a long axis of the inclusion, when the inclusion is observed in a cross section including a longitudinal axis of the wire; and concentrations in formulae (A) to (C) are normalized so that a total concentration of the three components SiO