Abstract

A Pb-free free-cutting steel for crankshafts was developed which resulted in the omission of the normalizing process. In order to omit the normalizing process, adequate hardness and fine microstructures, as obtained in normalized steel, must be achieved in the free-cutting steel after forging and air-cooling. These requirements were met by adjusting chemical composition of steel. A target was to achieve productivity of the developed steel based on Ca-S free-cutting steel, equal to that of the conventional Pb-S free-cutting steel. As a result of examining non-metallic inclusion’s composition, volume, shape and dispersion in the steel, it was found that the shape and dispersion contributed to an improvement in machinability. By manufacturing a crankshaft with this steel, the cost of the normalizing process was eliminated and the reduction of Pb by 13 g became possible for a motorcycle equipped with a 954 cm3 engine.

References

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Author (organization or company)

• Atsushi AMATAKA（Asaka R&D Center）
• Satoru SUWA（Asaka R&D Center）

Publication Information

Article of Honda R&D Technical Review Vol.14 No.1 (141 - 148)

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