| 摘要 |
PROBLEM TO BE SOLVED: To provide a method of producing connection rod for improving the proof stress and fatigue strength of an I-section part where, after integrated hot forging, cold coining (cold working) for shape straightening and subsequently, fracture separation is performed. SOLUTION: A stock consisting of non-heat treated steel for a connection rod having a composition containing, by weight, 0.20 to 0.70% C, 0.05 to 2.00% Si, 0.10 to 2.00% Mn, 0.01 to 0.20% P, 0.05 to 1.00% Cr, <=0.50% V, and 0.01 to 0.03% N, and the balance Fe with inevitable impurities is formed into a connection rod rough-formed body by hot forging. In this connection rod rough- formed body, cold coining for shape straightening is applied to an I-section, and, after that, aging treatment is performed thereto, so that the connection rod which can easily be subjected to fracture separation, and has excellent proof stress and fatigue strength in an I section is produced.
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