Nhk Spring Co., Ltd.

Hiroaki Ozawa

Hiroshi Koyama

Akira Ohno

Kanji Inoue

A hollow stabilizer manufactured from a material obtained by adding a minute amount (0.001-0.01% by weight) of boron to either a carbon steel tubing having a relatively low carbon concentration of 0.20-0.35% for mechanical and structural purposes or to a carbon steel tubing for general structural purposes. The carbon steel tubing thus provided is bent in a prescribed stabilizer form. The bent tubing is water quenched, for example, to a greater hardness than HRC 43. The water-hardened bent tubing is later tempered to a hardness HRC, ranging between 36 and 43, at a temperature of, for example, 300.degree.-380.degree. C. for a proper length of time. The hollow stabilizer obtained by the aforementioned heat-treating steps has a much greater fatigue strength.

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Yokohama, Japan

Hiroaki Ozawa