| 摘要 |
PURPOSE: A high stress steel for suspension springs is provided to reduce the weight of suspension spring by 30 % while holding a maximum stress of 130 kg/mm¬2. CONSTITUTION: The method for manufacturing a high stress steel for suspension springs includes the steps of heating a steel billet comprising C 0.4 to 0.6 wt.%, Si 2.8 to 4.0 wt.%, Mn 0.1 to 0.3 wt.%, Cr 0.3 to 0.6 wt.%, 0.0015 wt.% or less of O, N 0.005 to 0.01 wt.%, 0.01 wt.% or less of S and P, at least one element selected from V 0.01 to 0.1 wt.% and Ni 0.1 to 0.3 wt.%, a balance of Fe and incidental impurities in austenite region ranging from 900 t0 950 deg.C; holding the temperature for 10 to 15 min, followed by oil quenching; and tempering the steel billet in the temperature range of 350 to 430°C for 60 to 90 min.
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