Metallurgical Aspects of Fracture at High Strength Level
Abstract
The fracture toughness, Kc, of quenched and tempered sheet specimens of air-melted and cross rolled AISI 4340 was measured by procedures basically in accordance with those recommended by the special ASTM Committee on Fracture Testing. Kc was obtained from the elastic analysis of G. R. Irwin (ASM symposium, Fracturing of Metals, 1948, p. 152) with and without the plastic-zone correction, and by the elastic-plastic analysis of F. A. McClintock (ASTM bulletin, Apr. 1961, p. 277). The two values calculated from the Irwin analysis were essentially the same for specimens tempered below 400 degrees F, but without correction values were 15% lower for specimens tempered at 700 degrees F. Kc values calculated according to McClintock agree within 20% with the corrected Irwin values for specimens tempered between 500 degrees and 800 degrees F. Comparison of the Kc values with those of R. Rawe (Aerojet-General Corp., Rept. M2003, Feb. 1960) indicate that Kc for AISI 4340 was very sensitive to processing history. Extensive splitting, or delamination, along the plane of the sheet was observed in all fractures. This delamination might contribute to low plane-strain fracture toughness and high toughness-transition temperature.
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 01, 1962
- Accession Number
- AD0273705
Entities
People
- Merrill L. Ebner
- Walter A. Backofen
Organizations
- Massachusetts Institute of Technology