| abstract |
A steel wire for a spring is formed of a steel containing from 0.5% by mass to 0.8% by mass of carbon, from 1.0% by mass to 2.5% by mass of silicon, from 0.2% by mass to 1.0% by mass of manganese, and from 0.5% by mass to 2.5% by mass of chromium, the balance being iron and incidental impurities. The steel has a tempered martensite structure. The hardness of a surface region that is a region within 10 µm from an outer surface is from more than 0 HV to 50 HV higher than the hardness of a region other than the surface region. |