Skip to main content
U.S. Department of Energy
Office of Scientific and Technical Information

Intergranular fracture in 4340-type steels: effects of impurities and hydrogen. Final report, 8 December 1975--7 December 1976

Technical Report ·
OSTI ID:6825720
A study has been made of the conditions which lead to intergranular brittle fracture in 4340-type steels at an ultrahigh yield strength level (200 ksi, 1380 MPa) in both an ambient environment and gaseous hydrogen. By means of Charpy impact tests on commercial and high-purity steels, and by Auger electron spectroscopy of fracture surfaces, it is shown that one-step temper embrittlement (OSTE or '500 F embrittlement'), and low-K intergranular cracking in gaseous hydrogen are the result of segregation of P to prior austenite grain boundaries. Segregation of N also contributes to OSTE. Most, if not all, segregation apparently occurs during austenitization, rather than during tempering. These observations are discussed in terms of our understanding of the mechanisms of OSTE and hydrogen-assisted cracking.
Research Organization:
Pennsylvania Univ., Philadelphia (USA). Dept. of Metallurgy and Material Science
OSTI ID:
6825720
Report Number(s):
AD-A-054603
Country of Publication:
United States
Language:
English