Mechanical and acoustic properties of deformable alloys

Abstract

The paper is devoted to correlation dependences of ultrasound velocity with characteristics of strength and plasticity in uniaxial tension of Fe18Cr10Ni austenitic stainless steel with a unique set of physical and mechanical properties. Such a successful set of mechanical properties is provided by dislocation slip and twinning, the formation of stacking faults, and martensitic transformation. It should be noted that the assessment of changes in the mechanical characteristics of metals (especially at low temperatures) is a very laborious task and requires the use of non-destructive control methods. Experimental data was obtained using a bench designed to synchronize with recording of the “stress – strain” diagram for determining the values of ultrasound velocity propagation and the attenuation coefficient of the ultrasonic wave as a function of deformation. Measurement of ultrasound velocity propagation was reduced to determining the time of passage of an ultrasonic Rayleigh pulse between transmitting and receiving transducers. Attenuation was determined from the change in pulse shape. The pulses were excited by a piezoelectric transducer at a frequency of 5 MHz. The authors experimentally studied static loading effect on acoustic characteristics and calculated the destruction parameters. The propagation ultrasound velocity in deformable material is an informative feature for analyzing the nature of the processes that control plasticity. The effect of test temperature in the range 180 K ≤ T ≤ 320 K on acoustic and mechanical characteristics of the steel was studied to ensure control of its structural state and mechanical properties by means of non-destructive testing. The temperature range was chosen taking into account the possibility of direct γ → α′ martensitic transformation.