Dehydrogenation method for steel material and steel product, and production method for steel material and steel product

A dehydrogenation method for a steel material, wherein in a series of steel material production process including:

• a supply process of supplying a steel raw material;
• a hot working process of subjecting the steel raw material to hot working;
• an inspection process of inspecting a steel material obtained from the steel raw material;
• and a shipment process of shipping the steel material, at least one of the steel raw material and the steel material at any stage from the supply process to the shipment process is subjected to, at least once, a treatment of irradiating with sound waves, without contacting the steel raw material or the steel material, from a sound wave irradiator located apart from a surface of the steel raw material or the steel material and toward the surface, the sound wave irradiator includes a controller, a sound wave oscillator, a vibration transducer, a booster, a horn and a sound level meter, so that a sound pressure level at the surface of the at least one of the steel raw material and the steel material will be 30 dB or more and thereby hydrogen content in the steel material will be reduced.