Ultrasound velocity measurements in high-chromium steel under plastic deformation

In the present study, the variation of the propagation velocity of ultrasound in the plastic deformation of corrosion-resistant high-chromium steel 40X13 with ferrite-carbide (delivery status), martensitic (quenched) and sorbitol (after high-temperature tempering) structures have beem studied/ It is found that each state shows its view of the loading curve. In the delivery state diagram loading is substantially parabolic throughout, while in the martensitic state contains only linear strain hardening step and in the sorbitol state the plastic flow curve is three-step. The velocity of ultrasonic surface waves (Rayleigh waves) was measured simultaneously with the registration of the loading curve in the investigated steel in tension. It is shown that the dependence of the velocity of ultrasound in active loading is determined by the law of plastic flow, that is, the staging of the corresponding diagram of loading. Structural state of the investigated steel is not only changing the type of the deformation curve under uniaxial tension, but also changes the nature of ultrasound speed of deformation

Effect of hydrogen on plastic strain localization and fracture of steels

The effect of interstitial hydrogen atoms on the mechanical properties and plastic strain localization patterns in tensile tested specimens of low-carbon steels have been studied using a double exposure speckle photography technique. It is found that the mechanical properties of low-carbon steels are affected adversely by hydrogen embrittlement. The deformation diagrams were examined for the deformed samples of low-carbon steels. These are found to show all the plastic flow stages: the linear, parabolic and pre-failure stages would occur for the respective values of the exponent n from the Ludwik-Holomon equation

The Effect of Hydrogen on the Parameters of Plastic Deformation Localization in Low Carbon Steel

In the present study, the effect of interstitial hydrogen atoms on the mechanical properties and plastic strain localization patterns in tensile tested polycrystals of low-carbon steel Fe-0.07%C has been studied using double exposure speckle photography technique. The main parameters of plastic flow localization at various stages of deformation hardening have been determined in polycrystals of steel electrolytically saturated with hydrogen in a three-electrode electrochemical cell at a controlled constant cathode potential. Also, the effect of hydrogen on changing of microstructure by using optical microscopy has been demonstrated

Influence of hydrogen embrittlement on the localization of plastic strain in Al-Cu-Mg alloy

The influence of hydrogen embrittlement of the aluminum Al–4%Cu–0.2%Mg alloy on the parameters of localized plastic strain is studied. Digital speckle photography is used to visualize the localized strain patterns in the D1 alloy. The velocity of localized deformation bands as a function of the yield strength for nonhydrogenated and hydrogenated samples is found

Autowave process of the localized plastic deformation of high-chromium steel saturated with hydrogen

The deformation behavior of high-chromium stainless steel of sorbitic structure upon high-temperature tempering and of electrically saturated with hydrogen in the electrochemical cell during 12 hours is investigated. The stress-strain curves for each state were obtained. From the stress-strain curves, one can conclude that hydrogen markedly reduces the elongation to the fracture of specimen. Using double-exposed speckle photography method it was found that the plastic flow of the material is of a localized character. The pattern distribution of localized plastic flow domains at the linear hardening stage was investigated. Comparative study of autowave parameters was carried out for the tempered steel as well as the electrically saturated with hydrogen steel

Heterogeneity of plastic flow of bimetals electrolytically saturated with hydrogen

This paper presents the study of a corrosion-resistant bimetal composed of austenitic stainless steel (301 AISI) and low-carbon construction steel (A 283 Grade C) and the effect of its electrolytic hydrogenation on plastic flow of the test material. Localization patterns of plastic deformation in the process of uniaxial tension were obtained using the digital image correlation method. The evolution of localized plastic deformation zones was studied in the initial state and after electrolytic hydrogenation. The staging of stress-strain curves was analyzed

On the plastic flow localization of martensitic stainless steel saturated with hydrogen

The deformation behavior of tensile tested corrosion resistant high-chromium steel electrically saturated with hydrogen has been investigated. The studies were performed for high-temperature tempered steel with sorbitic structure and after electrolytic hydrogenation for 6 and 12 hours. It was found that hydrogen has markedly reduced the breaking stress and elongation leading to the fracture of the specimen. Using the method of double-exposed speckle photography, it was found that the plastic flow of the material had localized character. The evolution of localized-strain center distributions follows the law of plastic flow. The autowave parameters (autowave velocity and autowave length) were measured for every state of high-chromium steel under investigation and the difference between them is of great significance

Macroscopic criteria for the deformation and fracture of iron based alloys

In the article the deformation of different steels is analyzed using the autowave theory of plasticity. The article considers the possible use of an autowave model to formulate criteria for the structural strength of materials and elastic-plastic transition. The time and place of future fracture for steel samples are shown can be predicted before visible necking takes place by using the kinetic dependencies of localized plasticity domains at the prefracture stage. The results show that during elastic-plastic transition in lowcarbon steel, there is the break of the curve for the ultrasound velocity versus deformation, which can serve as an acoustic criterion of irreversible deformation for the pressure treatment of metals, the operation and nondestructive testing of products and structures