Accession Number : AD0660753

Title :   THE EFFECT OF HYDROGEN CHARGING ON THE PETCH RELATIONSHIP FOR ZONE-REFINED IRON.

Descriptive Note : Interim rept.,

Corporate Author : AEROSPACE RESEARCH LABS WRIGHT-PATTERSON AFB OHIO

Personal Author(s) : Adair,A. M.

Report Date : 21 JUN 1966

Pagination or Media Count : 7

Abstract : The effect of cathodically charging zone-refined iron with hydrogen and the resultant yield stress-grain size relationship has been investigated by tensile testing at -31C. The resulting Petch plots (using a least-squares analysis) reveal a significant reduction in the slope and an increase in the intercept for specimens cathodically charged with hydrogen, regardless of whether the hydrogen is present during testing or is removed by evacuation. Other than surface blistering, the major effect of cathodically charging this material is to create occasional grain boundary cracks and thus presumably a large number of free dislocations at grain boundaries. These results are consistent with the hypothesis that the slope of the Petch plot is related to the stress required to activate dislocation sources at or near grain boundaries. While there is no significant effect of the presence of hydrogen on the lower yield stress of this material, the ductility is considerably reduced. After hydrogen removal by evacuation, the ductility recovers substantially and almost complete recovery of ductility is experienced by the smaller grain size specimens. (Author)

Descriptors :   (*IRON, ZONE MELTING), HYDROGEN, GRAIN STRUCTURES(METALLURGY), TENSILE PROPERTIES, CRACKS, DISLOCATIONS, DUCTILITY

Subject Categories : Metallurgy and Metallography

Distribution Statement : APPROVED FOR PUBLIC RELEASE