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Title: Impact fracture toughness of porous iron and high-strength steels

Abstract

The impact fracture toughness of sintered iron and high-strength sintered steels, which densities between 7.0 and 7.25 g/cm{sup 3}, have been investigated by means of instrumented impact testing on fatigue-precracked as well as 0.17-mm-notched specimens. Experimental results show that the fracture behavior is controlled by the properties of the resisting necks at the crack/notch tip. The materials with impact yield strengths of up to 700 MPa display an increase in fracture toughness as the yield strength is increased. These materials undergo continuous yielding during loading, and ductile fracture takes place once the critical plastic strain is attained within a large process zone. A process-zone model, physically consistent with the fractographic observations, correctly rationalizes their impact fracture toughness. The materials with higher impact yield strengths display an impact curve which is linear up to fracture and are characterized by a fracture toughness which is independent of the yield strength. For these materials, the process zone reduces to the first necks at the crack/notch tip, and fracture takes place once the local applied stress-intensity factor reaches the fracture toughness of the matrix.

Authors:
Publication Date:
Research Org.:
Univ. of Trento (IT)
OSTI Identifier:
20075686
Alternate Identifier(s):
OSTI ID: 20075686
Resource Type:
Journal Article
Journal Name:
Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science
Additional Journal Information:
Journal Volume: 31; Journal Issue: 5; Other Information: PBD: May 2000; Journal ID: ISSN 1073-5623
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; IMPACT STRENGTH; FRACTURE PROPERTIES; IRON; STEELS; MOLYBDENUM ADDITIONS; POWDER METALLURGY; POROSITY; NOTCHES; MATHEMATICAL MODELS

Citation Formats

Straffelini, G. Impact fracture toughness of porous iron and high-strength steels. United States: N. p., 2000. Web. doi:10.1007/s11661-000-0262-4.
Straffelini, G. Impact fracture toughness of porous iron and high-strength steels. United States. doi:10.1007/s11661-000-0262-4.
Straffelini, G. Mon . "Impact fracture toughness of porous iron and high-strength steels". United States. doi:10.1007/s11661-000-0262-4.
@article{osti_20075686,
title = {Impact fracture toughness of porous iron and high-strength steels},
author = {Straffelini, G.},
abstractNote = {The impact fracture toughness of sintered iron and high-strength sintered steels, which densities between 7.0 and 7.25 g/cm{sup 3}, have been investigated by means of instrumented impact testing on fatigue-precracked as well as 0.17-mm-notched specimens. Experimental results show that the fracture behavior is controlled by the properties of the resisting necks at the crack/notch tip. The materials with impact yield strengths of up to 700 MPa display an increase in fracture toughness as the yield strength is increased. These materials undergo continuous yielding during loading, and ductile fracture takes place once the critical plastic strain is attained within a large process zone. A process-zone model, physically consistent with the fractographic observations, correctly rationalizes their impact fracture toughness. The materials with higher impact yield strengths display an impact curve which is linear up to fracture and are characterized by a fracture toughness which is independent of the yield strength. For these materials, the process zone reduces to the first necks at the crack/notch tip, and fracture takes place once the local applied stress-intensity factor reaches the fracture toughness of the matrix.},
doi = {10.1007/s11661-000-0262-4},
journal = {Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science},
issn = {1073-5623},
number = 5,
volume = 31,
place = {United States},
year = {2000},
month = {5}
}