| 摘要 |
PURPOSE:To manufacture a coil spring having high fatigue life, by subjecting a wire rod in which specific percentages of C, Si, Mn, Cr, V, and Mo are incorporated to Fe to patenting, cold wire drawing, oil tempering, and then coiling and by applying nitriding treatment to the above at a specific temp. CONSTITUTION:The wire rod consisting of 0.60-0.70% C, 1.30-1.70% Si, 0.40-0.70% Mn, 0.40-0.70% Cr, 0.40-0.60% V, 0.10-0.25% Mo, and the balance essentially Fe is successively subjected to patenting, cold wire drawing, oil tempering, and then coiling. Subsequently, this wire is subjected to nitriding treatment such as soft nitriding, low-temp. carbonitriding, etc., at a temp. in a region of 450-520 deg.C. In this way, the coil spring having high fatigue life can be obtained. This spring is suitable for valve spring for high speed engine. |
