Abstract
Study of degradation influence on material properties of some steel components is very important because of their serviceable life. One of the most important side of the degradation process considering operation conditions is cumulated plastic deformation. The ultrasonic investigation of materials through the ultrasound attenuation and velocity measurements have been proved an effective tool of the study of structural changes caused also by plastic deformation due to the degradation process. In the contribution we present the results of both the frequency dependence of ultrasound attenuation and velocity measurements of steel samples (38ChN3MFA) with different relative plastic deformation (0, 1.5, 3 and 6 %). The results are compared also with the measurements obtained by some other techniques, including the measurement of electrical conductivity, and the rate of positron-electron annihilation and breakage toughness.
Highlights
Quantities characterising the propagation of high-frequency acoustic waves in solid materials can be determined from the investigation of dependence of both acoustic waves velocity and attenuation on individual variables describing investigated properties of existing materials
In the range of 1.5 – 3 % of plastic deformation the marked increase of ultrasonic attenuation over 50 MHz was registered as increase of mean positron lifetime, which indicates a change in the state of lattice defects
Taking into consideration the fact, that the total plastic deformation depends directly on the density of dislocation lines in matrices, that should be necessarily changed during initial deformation phases the behaviour of both parameters are with largest probability the mark of raising sensitivity of both methods on the cluster creation of intersected dislocations during initial stages of plastic deformation
Summary
Quantities characterising the propagation of high-frequency acoustic waves (ultrasound) in solid materials can be determined from the investigation of dependence of both acoustic waves velocity and attenuation on individual variables describing investigated properties of existing materials. The relation of velocity and attenuation of ultrasonic waves to various properties referred to intrinsic structure of solid material can enable their study by means of ultrasonic velocity and attenuation measurement. Among these properties befit mainly elastic properties of materials, which reflect directly their intrinsic structure [1, 2]. The structure changes of existing material were investigated for various degrees of plastic deformation using both attenuation frequency dependence and ultrasound velocity measurements. Obtained results were in detail compared with results obtained by other methods on the same samples
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