Structural inheritance during heat treatment of forgings of steel 35KhN1M2F
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Heat treatment of steel 35KhN1M2F with a crystallographically ordered (martensitic or bainitic) structure after preliminary heating at 1100–1300° reestablishes the original grains size. If the structure is pearlitic after preliminary high-temperature heating then grain refining results from subsequent recrystallization.
With an original crystallographically ordered structure the original grain size is reestablished with repeated austenitizing at temperatures up to 900°. Recrystallization begins at 950°. The recrystallized grains are 1–2 grades smaller than the original grains.
Slow cooling in the austenitic range after heating at high temperature, prolonged high-temperature tempering before repeated heat treatment, and additional heat treatment with phase recrystallization weaken the structural inheritance, and promite grain refining.
To ensure a fine-grained structure in forgings of steel 35KhN1M2F after final heat treatment it is necessary to obtain a pearlitic structure in the process of cooling after forging.
If the bainitic transformation is suppressed in the process of cooling after forging and a pearlitic structure is obtained (with forging of rolled products, e. g.), then the grains can be refined by additional quenching or normalization at a higher temperature (950–1000°), ensuring recrystallization of the reestablished coarsegrained structure.
KeywordsHeat Treatment Recrystallization Slow Cool Additional Heat Rolled Product
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- 1.V. D. Sadovskii, Structural Inheritance in Steel [in Russian], Metallurgiya, Moscow (1973).Google Scholar