| 摘要 |
PROBLEM TO BE SOLVED: To manufacture a steering rack steel superior in bendability at a low cost. SOLUTION: A raw steel for the steering rack steel includes 0.40-0.60% C, 0.05-0.50% Si, 0.05-1.50% Mn, 0.004-0.100% S, further 1.5% or less Cr, 0.0005-0.10% Al, 0.002-0.020% N, as other elements, and the balance Fe with unavoidable impurities. The method for manufacturing the steering rack steel comprises rolling the above raw steel, heating the obtained steel bar at 820°C or higher, cooling it in a controlled condition, and tempering it at 680°C or higher in a short period of 20 minutes or less, to make the part of D/4 deep (D indicates a diameter of the steel bar) from the surface of the bar, to be a tempered bainitic structure and a tempered martensite structure occupying 20-100% (area percentage), and be a reproduced perlite structure occupying 0-50% (area percentage), by total area. COPYRIGHT: (C)2003,JPO
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