EXHAUSTION OF DUCTILITY UNDER NOTCH CONSTRAINT FOLLOWING UNIFORM PRESTRAINING.
Abstract
The purpose of the work was to measure the amount of uniform precompression of ABS-B and Project E-steel resulting in brittle fracture under the stron constraint of a subsequently machined severe circumferential groove. The elongation at the shoulders, measured with a special extensometer, was found to be a far more sensitive measure of brittleness than the average fracture stress. Prestrains as low as 0.05 caused a reduction of the elongation at the shoulders from about 0.017 - 0.050 in. to about 0.003 - 0.006 in. At low prestrains average fracture stress equaled or exceeded the theoretical flow limit of 2.68 sigma 0.1, where sigma 0.1 is the 0.1% offset yield stress in simple tension at the same prestrain. At a prestrain of 0.20 the fracture stress fell below the flow limit and at 0.60 it was close to sigma 0.1. The conditions of fracture at a notch in a strain hardening material are discussed. The total plastic elongation of a region surrounding a sharp notch in prestrained steel determines whether or not fracture will be initiated in large structures, hence is a direct and realistic measure of the remaining ductility and provides an excellent test of the material's resistance to embrittlement. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 01, 1966
- Accession Number
- AD0637143
Entities
People
- A. Armenakas
- C. Mylonas
- S. Kobayashi
Organizations
- Brown University