| 摘要 |
PURPOSE:To obtain the titled spring steel suitable for use as the material of a thick coil spring, a lapped thick flat spring, a torsion bar or the like by adding a proper amount of B to a high Si spring steel so as to provide a specified composition consisting of C, Si, Mn, B and Fe. CONSTITUTION:This spring steel with superior hardenability and sag resistance consists of, by weight, 0.50-0.80% C, 1.20-2.50% Si, 0.50-1.50% Mn, 0.0005- 0.0100% B and the balance Fe with impurity elements. The steel may further contain 0.20-2.00% Ni and/or 0.01-0.30% REM or one or more among 0.03- 0.30% Al, 0.02-0.30% Ti and 0.02-0.30% Zr. The steel has superior fatigue resistance and toughness besides said properties. Ni and REM improve the hardenability and toughness. Al, Ti and Zr make the austenite grains fine in the form of nitrides and improve the sag resistance.
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