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Toughness of tempered upper and lower bainitic microstructures in a 4150 steel

Journal Article · · Journal of Materials Engineering; (United States)
DOI:https://doi.org/10.1007/BF02660294· OSTI ID:6491773
;  [1]
  1. Univ. of Tennessee, Knoxville (United States)

The effects of tempering on the Charpy impact toughness and tensile properties of upper and lower bainite in a 4,150 steel have been studied. The results correlate with quantitative measurements taken from both the fracture surfaces and the microstructures of Charpy test specimens. The fracture surfaces from impact specimens having a lower bainitic microstructure were characterized by quasicleavage fracture, whereas those having an upper bainitic microstructure exhibited only cleavage fracture. The quasicleavage facet size and cleavage facet size correlate with bainite packet size and bainite block size. After tempering at high temperatures, the impact toughness is greatly improved for both the upper and lower bainitic microstructures. Changes in toughness correlate with the microstructural change in carbide shape and distribution resulting from the different tempering operations.

OSTI ID:
6491773
Journal Information:
Journal of Materials Engineering; (United States), Journal Name: Journal of Materials Engineering; (United States) Vol. 2:2; ISSN JMAEEV; ISSN 0931-7058
Country of Publication:
United States
Language:
English