| Abstract: | | 1. |
Obtaining a polygonized structure in hot forming of austenite in a cycle of HTMT of steels 40Kh, 40KhN, and 40KhN2MA causes an increase of the resistance to brittle failure: after low tempering and embrittling tempering at 500°C (for 200 h) the level of impact toughness increases at normal as well as subzero temperatures; the critical brittle point is lowered; the fraction of crystalline component in the fracture decreases.
| | 2. |
Hot forming of structural steels with 0.4% C at the steady state of dynamic polygonization (  50%) even with partial development of dynamic recrystallization (up to 30% vol. %) is more preferred for reducing disposition to temper brittleness than at the stage of nonsteady dynamic polygonization (25%). Obtaining fully dynamically recrystallized austenite with finer grain than the initial one reduces to a lesser extent the disposition of steels to temper brittleness.
| | 3. |
The lowering of the critical brittle point T20 as a result of HTMT of steels is directly proportional to the decrease of the fraction of intergranular failure.
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Moscow Institute of Steel and Alloys. Central Research Institute of Steel Structure Projects. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 6, pp. 44–48, June, 1989. |
