The Microstructure and Tensile Properties of New High-Manganese Low-Activation Austenitic Steel

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A new low-activation austenitic steel with a modified composition and high austenite stability is proposed. The features of its microstructure after solution treatment (ST) and cold rolling (CR) are studied. The mechanical properties and features of the fracture behavior of this steel under tensile tests in the temperature range of 20–750 °C are discussed. After ST, an austenitic structure with stacking faults and dispersed carbide particles of the MC and M23C6 types is observed in the steel. After CR, the grains are refined, and the average grain size decreases from 41.4 µm (after ST) to 33.9 µm. High-density microtwin packets form in the material, and the dislocation density increases relative to that after ST. As the test temperature increases from 20 to 750 °C, the yield strength of the steel decreases by approximately two times, from ≈300 to 150 MPa (for ST) and from ≈700 to 370 MPa (for CR). In the studied temperature range, the steel demonstrates up to 2.6 times higher values of elongation to failure, ≈40–80% (for ST) and ≈13–27% (for CR), compared to steels of similar compositions and lower manganese content. Mechanical twinning contributes to the high steel ductility up to 300 °C. Signs of discontinuous flow in the tensile curves after ST in the temperature range of 500–600 °C and a decrease in the elongation to failure in the close temperature range indicate dynamic strain aging (DSA). Steel fracture after tension at all test temperatures mainly occurs via a ductile dimple transcrystalline mechanism with elements of ductile intercrystalline fracture. It is shown that cracks nucleate on clusters of dispersed second-phase particles. The mechanisms of plastic deformation, fracture, and strengthening of the proposed modified low-activation austenitic steel are discussed.

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…%, and a carbon content of 0.25 wt. %, additionally alloyed with strong carbide-forming elements [19,20]. It has a nickel equivalent of 22.5, calculated from the actual composition.…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Microstructure Features and Mechanical Properties of Modified Low-Activation Austenitic Steel in the Temperature Range of 20 to 750 °C

Litovchenko,

Akkuzin,

Polekhina

et al. 2023

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The Microstructure and Tensile Properties of New High-Manganese Low-Activation Austenitic Steel

Litovchenko

Аккузин

Polekhina

et al. 2022

Using X-ray diffraction, scanning and transmission electron microscopy, the microstructure of a new low-activation chromium-manganese austenitic steel with a high content of manganese and strong carbide-forming elements is studied. Its structure, dislocation character and particle composition are detailed. The processes taking place in the steel under cold-rolling deformation are described. It is shown that the mechanical properties of the new high-manganese steel revealed by testing at 20 and 650 °C are comparable with those of well-known analogs or exceed them. Relying on the structural studies, this is attributed to the dispersion and substructural strengthening. Better plastic properties of the steel are associated with the twinning-induced plasticity effect. It is shown that the steel fracture after tension at the test temperatures is mainly ductile dimple transcrystalline with the elements of ductile intercrystalline fracture (at 20 °C), while at 650 °C the signs of the latter disappear. The low-activation chromium-manganese austenitic steels characterized by increased austenite stability are thought to be promising structural materials for nuclear power engineering.

Detection of Phase Transformation during Plastic Deformation of Metastable Austenitic Steel AISI 304L by Means of X-ray Diffraction Pattern Analysis

Vasquez

Arian

Kersting

et al. 2023

This paper evaluates the suitability of the X-ray diffraction (XRD) technique to characterize the phase transformation during the metal forming of the metastable austenitic steel AISI 304L. Due to plastic deformation, phase transformation from γ-austenite into α’-martensite occurs. The XRD peaks at specific 2θ diffraction angles give information about the phase amount. Analyses of the results with different characterization techniques such as microscopic analysis, including electron backscatter diffraction (EBSD), macro- and microhardness tests and magneto-inductive measurements of α’-martensite, were carried out. A qualitative and quantitative correlation to compute the amount of α’-martensite from the XRD measurements was deduced. XRD was validated as a suitable technique to characterize the phase transformation of metastable austenites. Additional data could provide necessary information to develop a more reliable model to perform a quantitative analysis of the phases from XRD measurements.