THE PRINCIPLES OF DISPERSION HARDENING WHICH PROMOTE HIGH-TEMPERATURE STRENGTH IN IRON-BASE ALLOYS. Period Covered: March 1, 1957 to February 29, 1958

Technical Report · Tue Apr 01 04:00:00 EST 1958

OSTI ID:4295406

Underwood, E E; Wolff, A K; Marsh, L L; Manning, G K

Eleven alloys, based on iron--18% chromium, were prepared with up to 16% nickel so that the alpha -, alpha + gamma -, and gamma -phase fields were represented. Creep, tensile, and hardness measurements were obtained between 80 and 1700 deg F. The plasticity reserve'' of Ivanova (rupture time times minimum creep rate) and the empirical relation of Monkman and Grant (between rupture time and minimum creep rate) are examined from a common viewpoint. Both compositional and temperature dependences are established in their relationships. The combined stress-time function is applied to isochronous stress-strain curves out to strains of 30%. Curves of plasticity reserve, ductility at fracture, break (equicohesive) temperature, and the constants in the Rabotnov and Larson-Miller parameters are shown to be related. The strength and stability of the alloys are examined with reference to their break temperatures. The strength of single- phase alloys varies with break temperature, but two-phase alloys show no simple dependence. The hardening influence'' of titanium, beryllium, manganese, cobalt, and nickel solutes reveals both solution hardening and solution softening at elevated temperatures. An opposite strain-rate effect is apparent on the ductilily at fracture of alpha and gamma alloys. The strength-hardness correlation proposed earlier has been verified with Alloy S-590 over wide ranges of stresses, times, and temperatures. An inversion in the relative strengthening ability of alloys with coarse and fine spacings appears to conform to the scheme advanced by Giedt. Sherby, and Dorn. (auth)

• Research Organization: Battelle Memorial Inst., Columbus, Ohio
• NSA Number: NSA-13-000765
• OSTI ID: 4295406
• Report Number(s): WADC-TR-56-184(Pt.3); AD-15565
• Country of Publication: United States
• Language: English

Related Subjects

BERYLLIUM ALLOYS
CHROMIUM ALLOYS
COBALT ALLOYS
DEFECTS
DUCTILITY
HIGH TEMPERATURE
IRON ALLOYS
MANGANESE ALLOYS
MECHANICAL PROPERTIES
METALLURGY AND CERAMICS
NICKEL ALLOYS
PHASE DIAGRAMS
SOLID SOLUTIONS
TENSILE PROPERTIES
TITANIUM ALLOYS