Patents by Inventor Bertil J. Hagstad

Bertil J. Hagstad 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: 4575912
    Abstract: The invention relates to a steel and a process for its manufacture which is suitable for the production of springs, especially leafsprings for vehicles. The steel which is vacuum-treated is an ordinary low-carbon steel with 0.20-0.04% C. Its composition is incidentally characterized in that the oxygen content does not exceed 0.040% and in that boron is added to an amount of 0.002-0.004% and titanium to an amount of 0.015-0.050%. The addition of boron causes the hardenability to increase greatly, thus making it possible to keep the carbon content low and, in consequence, reducing the danger of destructive decarbonization.A characteristic of the process of production consists in the fact that the steel is produced in an oxygen converter in such a manner that the nitrogen content in the ladle does not exceed 20 ppm, in that it is subsequently subjected to vacuum treatment and in that Al is added so that the amount of uncombined oxygen drops to max.
    Type: Grant
    Filed: May 7, 1984
    Date of Patent: March 18, 1986
    Assignee: SSAB Svenskt Stal AB
    Inventors: Carl E. Grip, Bertil J. Hagstad, Bjorn H. Andersson