ISSN:
1573-8973
Quelle:
Springer Online Journal Archives 1860-2000
Thema:
Maschinenbau
Notizen:
Conclusions 1. Stepped cooling with supercooling to 250–350°C creates thermal stresses in forgings, since decomposition of supercooled austenite to martensite is prevented. The magnitude and character of the stresses depend on the cooling rate from the austenitizing temperature (final forging temperature) down to 250–350°. 2. With increasing cooling rates the stresses reach substantial values, with the temperature gradient highest for cooling in oil or a water-air mixture. However, these stresses are not dangerous, since the metal still has a high plasticity. 3. The most commonly used cooling medium is moving air. This treatment not only sharply reduces the cooling time (to 30–45 min/100 mm of cross section) down to 250–350° but substantially reduces the stresses. 4. The most dangerous stresses in cooling of forgings are tangential surface stresses. However, they reach their highest values at the time the temperature gradient is highest, when the metal still retains its high plasticity. 5. With stepped cooling in moving air the cooling time is reduced 25–40% or more.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1007/BF00650841
