Nissan Motor Company Limited

Daido Steel Co., Ltd.

Wataru Naitou

Jun Yoshida

Sadayuki Nakamura

Yoshio Okada

Tomonori Miyazawa

Koichiro Inoue

Kouji Itakura

Noriyuki Shiwaku

Hideaki Ohtaka

Hidetoshi Satou

Disclosed is a non-heat treated steel for hot forging, particularly suitable for producing connecting rods of automobile engines. The steel consists essentially of: by weight, C: 0.3-0.8%, Si: 0.1-2.0%, Mn: 0.3-1.5%, P: 0.01-0.15%, Cr: 0-1.0%, V: 0-0.4%, Al: 0-0.05%, N: 0.005-0.03% and the balance being Fe and inevitable impurities, provided that the contents of C, Mn and Cr fulfill the following condition: 1.40[C %]+0.28[Mn %]+0.50[Cr %]&#x2267;0.75 Pearlite area fraction in this steel after hot forging is 50% or more. Notches are provided with laser beam on an intermediate part at the location from which fracture starts, and load is applied. Then, the intermediate is split to be two components (big end or cap and small end/rod for connecting rod). The components are adhered to form the parts.

Non-heat treated steel for hot forging with easy fracture splitting

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Yokohama, Japan

Wataru Naitou