Issue 42

D. V. Orlova et alii, Frattura ed Integrità Strutturale, 42 (2017) 293-302; DOI: 10.3221/IGF-ESIS.42.31 293 Macroscopic criteria for the deformation and fracture of iron based alloys Dina V. Orlova, Alexey G. Lunev, Lidiya V. Danilova, Lev B. Zuev Institute of Strength Physics and Materials Science SB RAS, 2/4 Akademicheskii Ave., 634055 Tomsk, Russia dvo@ispms.tsc.ru A BSTRACT . 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 pre- fracture stage. The results show that during elastic-plastic transition in low- carbon 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 non- destructive testing of products and structures. K EYWORDS . Steels, Ductile Fracture; Ultrasound Velocity; Digital Speckle Photography. Citation: Orlova, D.V., Lunev, A.G., Danilova, L.V., Zuev, L.B., Macroscopic criteria for the deformation and fracture of iron based alloys, Frattura ed Integrità Strutturale, 42 (2017) 293-302. Received: 04.07.2017 Accepted: 15.08.2017 Published: 01.10.2017 Copyright: © 2017 This is an open access article under the terms of the CC-BY 4.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. I NTRODUCTION t present, the critical parts and structures of many hazardous production facilities operate under mechanical loads which initiate the occurrence and accumulation of damages leading to the fracture of equipment. These damages can be timely identified and eliminated if appropriate technical means and methods are available. In this connection, special attention is paid to the problem concerning the objective and reliable estimation of the mechanical condition and the prediction of the resource for critical elements and structures in the long operation. Since the localized development of a plastic flow has a significant effect on the strength and plastic characteristics of structural steel products, it is of importance to describe the kinetics of a plastic flow and the transition from deformation to ductile fracture. The progressive development of the dislocation theory using high-resolution techniques, mainly electron microscopy, allowed a number of efficient models to be developed for the strain and impurity hardening of metals, as well as for the micromechanics of fracture [1-9]. Nevertheless, the kinetics of a plastic flow was not insufficiently described. It is difficult to add the time factor to the equations of plasticity. For example, the Taylor-Orowan equation obtained for this purpose A