SPRING WIRE ROD EXCELLING IN FATIGUE CHARACTERISTICS

摘要

Disclosed herein is a spring wire rod excelling in fatigue characteristics. It contains TiN inclusions having a specific size defined by the ratio of each group in all the visual fields as follows: (1) Visual fields in which the maximum thickness is no larger than 5 mum: less than 5% (2) Visual fields in which the maximum thickness is larger than 5 mum and no larger than 10 mum: no more than 30% (3) Visual fields in which the maximum thickness is larger than 10 mum and no larger than 25 mum: no less than 70% (4) Visual fields in which the maximum thickness is larger than 25 mum: less than 5% The visual field is the cross section passing through the center line of the wire rod.