Varieties of upper bainite in steels of the pearlitic class

Conclusions

• 1. Upper bainite may be low-carbon and high-carbon. The formation of low- and high-carbon bainites is initiated by the α-phase and carbide phase, respectively.

• 2. High-carbon upper bainite, which forms in steels alloyed with carbide-forming elements, may have a feathered, dendritelike, or comb-shaped structure, depending on the temperature of the phase transition.

• 3. High-carbon upper bainite in carbon steels and steels alloyed with non-carbide-forming elements has a feathered structure.