We have investigated several speciments of ASTM A710 steel containing copper-rich precipitates with variations in the final aging treatment. X-ray diffraction line-broadening and small-angle neutron-scattering experiments revealed the existence of the precipitates and associated coherency strain. We determined the nonlinear ultrasonic parameter beta for each specimen by harmonic-generation experiments and measured the ultrasonic longitudinal velocity v_L and attenuation alpah _L. Although v_L and alpah _L showed no consistent trends, beta increased with increasing strain. Theis correlation is compared to a microstructural model for harmonic generation that includes acontribution from precipitate-pinned dislocations.
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