THE MECHANICAL PROPERTIES OF IRRADIATED IRON AND IRON ALLOYS

Technical Report · Mon Jan 01 00:00:00 EST 1962

OSTI ID:4739427

Chow, J G.Y.; McRickard, S B; Gurinsky, D H

The effects of fast neutron irradiation on the yielding, plastic flow, and fracture properties of pure iron: iron alloyed with carbon, and iron alloyed with chromium were studied as part of an investigation of irradiation damage in bcc metals. In addition, two documented steels, A212B and Mod HY80, were also analyzed. In the pure iron, the K/sub gamma / term in the relation correlating yield stress with grain size, namely 122 to 158 deg /sub ys/ = 122 to 158 deg /sub i/ + K/sub y/d/sup -1/2/, was reduced to zero by irradiation. Instead, the post irradiation yield stress was inversely proportional to the log l/T. Further, an exposure of 2 x 18/sup 18/ nvt or greater produced a sharp ductile to brittle transition point with a shift of 85 nif- K in pure iron. This same exposure level also had the effect of producing a linear true stress-true strain curve similar to that obtained from prestrained iron with the apparent elimination of the initial rapid work hardening portion of the curve. The effect of carbon additions up to 0.11 wt.% was to increase the yield strength and decrease the ductility before irradiation. However, the post irradiation mechanical properties regardless of the carbon content were approximately the same as those of pure iron. The linear variation of yield strength with the log l/T was not followed by the irradiated carbon alloys. The addition of chromium decreased the yield strength and increased the ductility of both unirradiated and irradiated iron. The linear true stresstrue strain curve was obtained and the yield stress varied with the log l/T after the 2 x 10/sup 18/ nvt exposure. No sharp ductile to brittle transition point was observed. The two steels generally showed increased strength and some decrease in ductility without a sharp ductile to brittle transition point after irradiation. These results are explained by attributing the initial increases in strength and decreases in ductility to radiation produced point defects. After a certain level of exposure was reached, these defects became saturated and vacancy loops were created which tangle with slip dislocations. These tangles create a dislocation cell structure similar to that found in cold worked metals. This structure resulted in the independence of yield strength on grain size and a linear flow curve in irradiated iron. Carbon atoms annihilated some of the vacancies requiring higher exposures for saturation to be reached while chromium was thought to tie up the carbon atoms in carbides facilitating the process. Similarly, the additional elements in the steels were thought in some way to impede the development of the radioinduced cell structure. (suth)

• Research Organization: Brookhaven National Lab., Upton, N.Y.
• DOE Contract Number: AT(30-2)-GEN-16
• NSA Number: NSA-17-018852
• OSTI ID: 4739427
• Report Number(s): BNL-6249
• Resource Relation: Other Information: Orig. Receipt Date: 31-DEC-63
• Country of Publication: United States
• Language: English

Related Subjects

METALS, CERAMICS, AND OTHER MATERIALS
ATOMS
BRITTLENESS
CARBON
CHROMIUM ALLOYS
CREEP
DEFECTS
DEFORMATION
DIAGRAMS
DISLOCATIONS
DUCTILITY
FAILURES
FAST NEUTRONS
GRAIN SIZE
IRON
IRON ALLOYS
IRON CARBIDES
IRRADIATION
MECHANICAL PROPERTIES
QUANTITY RATIO
RADIATION EFFECTS
SLIP
STEELS
STRESSES
TEMPERING
TENSILE PROPERTIES
VACANCIES
VARIATIONS