| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a rack and pinion type steering device hardly being damaged in manufacturing. Ž<P>SOLUTION: A rack 21 for the rack and pinion type steering device is made of steel having a carbon content of 0.35 mass% or more and 0.55 mass% or less and a sulfur content of 0.035 mass% or less. That is, the rack is manufactured in such a manner that it is molded into a prescribed shape by cold forging after rod-like or tubular material made of the steel is softened and annealed, and is further subjected to induction hardening. The material (the material after dehardening and annealing and before cold forging) has hardness of HV200 or less by dehardening and annealing, and has a structure containing spheroidal cementite, acicular cementite, and ferrite. Further, the relationship between Vickers hardness H of the material and an amount Cs (mass%) of sulfur contained in the steel satisfies the expression; H+2,000×Cs≤240. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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