STRUCTURAL SUPER-HIGH PLASTICITY OF STEELS

Аннотация

This chapter discusses the significant enhancement of steel plasticity when transformed into a hollow state, with a focus on structural superplasticity. It examines the behavior of microstructured steels with ultrafine grains at elevated temperatures and explores the influence of phase transitions, carbon content, and alloying elements on the microstructure. Particular attention is given to the deformation behavior of technically pure iron during heating andphase changes. Keywords: Steel plasticity, superplasticity, microstructure, phase transition, pure iron, ferrite, austenite, deformation temperature Technicalpureiron plasticity anomaly It is possible to dramatically increase the plasticity of steel by transferring it to a hollow state. In this chapter, the structural superclasticity of Steel is considered. Due to the fact that OYUPD is observed at temperatures above 0.4-0.5 Tpl, it will be necessary to consider the possibility of obtaining microstructured steel with ultra-small grains at these temperatures. In steels, both Matrix and microduplex microstructure can be formed due to the polymorphism of iron, as well as due to the large dependence of the microstructure and phase composition on the amount of carbon, the amount of elements that legitimize and the heating temperature. When heated, the microstructure of steels can change greatly as a result of phase changes. In the field of one phase https://ijmri.de/index.php/jmsi volume 4,issue4,2025 1163 or another, respectively, it is better to start observing the etching deformation from iron-carbon alloys [13]. Of interest is primarily the technical consideration of the plasticity of pure iron depending on the deformation temperature and its association with changes in phase and microstructure in heating. When iron is heated, ferrite grains become unstable, growth occurs violently. At temperatures corresponding to critical iron points, the microstructure of iron is large-grained. More high extensions in technical pure iron [10] are observed at temperatures close to the temperature at which the change begins, as noted in the work. In the field of Phase rotations of technical pure iron with a content of 0.006% s, the α"γ elongation increases significantly as the αγ approaches the temperature at which the rotation begins, reaching a maximum (50%) at the highest temperature where the single – phase State (ferrite) is present at 850 S. When switching to austenite-ferritedomain, the occurrence ofaustenite leads to asharp decrease in elongation byup to 5%. In the austenite area, the elongation increases with increasing temperature and is 30% at 1000C [3]. The tensile stress increases monotonically as the deformation temperature increases. In the area of Phase Change, an increase in the voltage of the current is noted in one micror. In the field of phase change, the nature of the temperature Binding of the relative elongation of iron is very close to the temperature Binding of the technical pure titanium plasticity seen above. Such a case can be explained from the assumption of differences in the deformation descriptions of the phases of Super-highiplastic Ferrite and less plastic austenite [10]. However, no data has been cited ontheexact structure that supports this assumption. The data considered on the plasticity of iron in the phase change interval [4] is not consistent with theresults ofthework. The authors show that iron containing 0.017% S in the range of polymorphic growth temperatures has higher values of m (0.6) and ẟ (≥≥150%). But [9, 10] there is no way to determine thecause ofdifferences indata dueto thelack ofstructural studies intheworks. An increase in carbon content and the consequent separation of cementite in steel should have a stabilizing effect on the microstructure. The OEUP symptoms found when testing a 50% cold spread steel with acontent of0.05%S fordisplacement indirectly confirm this[4]. When heating at a deformation temperature (540 C), an equal-axis microstructure with a grain size of 5-7 µm is formed in steel. At the same temperature and 5-10 MPa loadings, a uniform relative elongation of up to 80% was observed, with values of ϭ strongly dependent on the magnitude of the applied force. The extension also began to decrease when the voltages decreased. It should be noted that in the following years, many data [10,5] have appeared that confirm an increase in plasticity in the interval of phase changes from as1 to AS2. Other confirmed and experimentally proven [9, 8] opinions that plasticity does not increase in the interval of opposite AS1-AS2 phasechanges, but decreases rather, havealso been. Such contradictions are largely due to the fact that it is much more difficult to systematically study the mechanical properties of iron at the time of phase change, especially its microstructure. Therefore, the study of plasticity in technical pure iron at different deformation temperatures and especially in thefield ofPhase Rotationis oneofthe