An Electrical Device for Automatically Indicating by Visual or Audible Means the Correct Temperature of Electrically Heated Steel before Quenching in Order to Obtain Correct Hardening thereof.

摘要

130,191. Alexander, H., Vint, W. T., and Imbery, A. Aug. 22, 1918. Hardening.-Relates to means for determining, during the heat-treatment of steel, the temperature to which the steel must be heated before quenching. The steel article, which may be a moving wire 1, is heated by alternating current, and is surrounded by a coil 4 in series with a telephone receiver 5, and the variations in the sound heard in the receiver 5 caused by changes in the magnetic properties of the steel are observed. A calibrated voltmeter may be used in addition to the receiver 5, where a visual indication is also required.