OPTIMUM FATIGUE CRACK RESISTANCE.
WATERVLIET ARSENAL N Y
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An evaluation is made of the influence of mechanical properties on fatigue-crack growth rate. Data representing 4340 and modified 4330 steel show that for levels of the stress intensity factor K below about 40 ksi sq root of in. mechanical properties have little influence on growth rate. However, at higher K-levels both the product of Youngs modulus, yield strength and fracture toughness, and the product of Youngs modulus, tensile strength and true strain at fracture seem to be reasonable indices of crack growth resistance. For K-levels above 40 ksi sq root of in. minimum fatigue-crack growth rate is provided by tempering 4340 and modified 4330 at temperatures of about 1000 and 1100 F, respectively. Author
- Metallurgy and Metallography
- Solid State Physics