1. Research on the Elimination of Banded Structure in SAE8620H Gear Steel
- Author
-
Heng Hua Zhang, Zhen Ming Lin, Man Jin, and Jing Li
- Subjects
Materials science ,Transition temperature ,Metallurgy ,Alloy ,General Engineering ,Nucleation ,engineering.material ,Isothermal process ,Ferrite (iron) ,Isothermal annealing ,engineering ,Pearlite ,Composite material ,Supercooling - Abstract
In order to eliminating the banded structure in SAE8620H gear steel,an isothermal annealing process and its mechanism has been studied in this paper. Results showed that isothermal annealing process can effectively eliminate banded structure in SAE8620H gear steel.With isothermal temperature 640°C-a certain low temperature indeed high undercooling,and for high nucleation at this temperature resulting in the decrease of nucleation rate difference in all areas,banded structure level decreased to 1 level.When isothermal temperature decreased to 610°C and 590°C,although the undercooling is so high that various regions began to nucleate at the same time,the transition temperature is so low that alloy elements in the regions previously occupied by pearlite bands diffuse faster than other regions,thus proeutectoid ferrite grains in these regions grow faster,regenerating the banded structure .
- Published
- 2015