HEAT TREATMENT OF STEEL PRODUCTS

摘要

PURPOSE:To heat the entire part of steel products to a uniform temp. and to prevent the ununiformity in the treatment arising from the uneven temp. by cooling quickly the heated steel products down to a prescribed temp. then holding the same within a fluidized layer of approximately the same temp. as the treatment temp. after quick cooling. CONSTITUTION:The formed parts emitted from a hot forging machine 1 or the heated steel parts 3 emitted from a heating furnace 2 are the steel members which are plastically worked in a recrystallization austenite temp. region. Such parts are cooled down to the unrecrystallization austenite region or two-phase co-existence region of ferrite and austenite by a quick cooler 4. The parts are then put into the fluidized layer 5 consisting of fluid particles such as <=150mesh zircon sand maintained at the above-mentioned temp. region and are held therein for about 1 minutes to hat uniformly the entire part of the steel products to the above-mentioned temp. The steel products are thereafter plastically worked. The crystal grains are fined by the working in the unrecrystallization austenite, by which the toughness is improved.