Patents by Inventor Hae C. Choi

Hae C. Choi has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 5575973
    Abstract: A low decarburization high toughness spring steel for an automobile suspending spring, and a manufacturing process therefor, are disclosed. In this steel, the effect of the sag resistance promoting element (Si) is maximized without reducing the carbon content, so that the problems of the decarburization and the lowering of the toughness (caused by the addition of silicon) should be solved during the manufacturing of the spring steel. The spring steel of the present invention is composed of in weight %: 0.5-0.7% of C, 1.0-3.5% of Si, 0.3-1.5% of Mn, 0.3-1.0% of Cr, 0.05-0.5% of V and/or Nb, less than 0.02% of P, less than 0.02% of S, 0.5-5.0% of Ni, and other indispensable impurities, the balance being Fe.
    Type: Grant
    Filed: August 9, 1995
    Date of Patent: November 19, 1996
    Assignees: Pohang Iron & Steel Co., Ltd., Research Institute of Industrial Science & Technology
    Inventors: Hae C. Choi, Won J. Nam, Jong K. Choi, Soo D. Bark, Jong H. Choi, Jang G. Kim