Microstructure and Mechanical Properties of Metals and Alloys Deformed in Liquid Nitrogen: Review

Vasiliev, M. O.; Voloshko, S. М.; Yatsenko, L. P.

doi:10.15407/ufm.13.03.303

Cited by 10 publications

(2 citation statements)

References 39 publications

(46 reference statements)

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“…Accordingly, the final squeezing of such green compacts did not provide for a fundamental increase in strength, which grew to only 300 MPa (Table 3), which is less than during final squeezing at room temperature. Cooling in liquid nitrogen leads to a decrease in the plasticity of the material, which is typical of metals with a BCC lattice [16,17], so the embrittlement of the material led to the grinding of grains, which is confirmed by the results of metallographic analysis (Fig. 4).…”

Section: Discussion Of Results Of Studying the Effect Of Final Squeezmentioning

confidence: 70%

Determining the influence exerted by the static conditions of final squeezing on the compaction process of iron-based powder materials

Minitsky

Minitska

Okhrimenko

et al. 2021

EEJET

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This paper reports a study into the process of re-compaction of powder briquettes in the conditions of static pressing at a pressure of 800 MPa. The technological parameters of the pressing process have been analyzed, which make it possible to improve the compaction of powder briquettes based on iron. Such parameters are the outer greasing, which reduces friction between a green compact and the walls of the press tool matrix, and the firing, which removes the deformation strengthening of the green compacts and increases their plasticity. The green compacts’ sealing mechanism involved in the final squeezing process has been established, which is associated with the grinding of pre-compressed particles due to the strain in the contact areas. The increase in the stressed state of green compacts following the final squeezing was confirmed by the results of studying the residual micro-strains. The change in the stressed state of iron green compacts has been confirmed by the study into the structurally sensitive characteristics, which include the materials’ magnetic and electrical properties. Determining the magnetic characteristics has shown that final squeezing leads to an increase in coercive force, which can be explained by both the increase in the stressed state and the grinding of grains. Investigating the impact exerted by the annealing environment on the value of magnetic characteristics has demonstrated that annealing in hydrogen is more effective in terms of improving magnetic properties than annealing in a vacuum. This is due to the refining of grain boundaries through the processes of reduction of oxide films. The study of the mechanical characteristics of green compact materials based on iron powder has established that final squeezing leads to an increase in the hardness and strength of materials depending on the conditions of deformation. A significant improvement in the green compacts’ strength (820‒824 MPa) is due to both a decrease in porosity by 8‒10 % and an increase in the contact area as a result of plastic deformation after the annealing

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Section: Discussion Of Results Of Studying the Effect Of Final Squeezmentioning

confidence: 70%

Determining the influence exerted by the static conditions of final squeezing on the compaction process of iron-based powder materials

Minitsky

Minitska

Okhrimenko

et al. 2021

EEJET

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“…Tis is especially clearly seen in plastic deformation at low temperatures when the structure resulting at room temperature begins to change without any infuence [23]. It is known that rolling at low temperatures leads to strong fragmentation of the grain structure up to a crystallite size of 35 nm [24]. Today, for example, almost all SPD methods of titanium alloys are implemented at temperatures not exceeding 300-400 °C to eliminate recrystallization processes in billets.…”

Section: Introductionmentioning

confidence: 99%

Structure and Mechanical Properties of Titanium Processed by Twist Extrusion and Subsequent Rolling

Tarasov

Gribkov

Павленко

et al. 2022

Advances in Materials Science and Engineering

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The article considers one of the combined methods of severe plastic deformation (SPD), which includes twist extrusion (TE) and subsequent rolling. The use of combined forming methods is promising for industrial use. Titanium grade 1 was used as a material in the experiments. Rolling was carried out in three stages with a decrease in temperature from 350°C to 180°C for a number of passes with one heating. The accumulated strain degree was e = 4.6 at twist extrusion and e = 3 in rolling. Increasing the reduction per pass decreases the number of heatings and increases the efficiency of the rolling process in whole. At the same time, it is necessary to set the maximum processing modes at which recrystallization processes do not occur in the billet. When rolling, the deformation degree in one pass was taken in the range of 5–20% with an increase in successive passes. The use of such deformation degrees allowed reducing the grain size in titanium grade 1 significantly. Twist extrusion reduces the grain size to 300–500 nm. Subsequent rolling allowed reducing the size of structural elements to 50–100 nm and provided a significant increase in the mechanical characteristics of the billet material (up to 869 MPa) while maintaining satisfactory ductility (up to 11.6%). It was found that increasing the deformation degree in one pass up to 40% at cross-rolling and simultaneously increasing the temperature to 385°C led to a decrease in the UFG structure quality and reduced strength of the deformable material by starting the dynamic recrystallization process.

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Analysis of the effect of cryogenic cooling during drawing on AISI-316 steel wire properties

Volokitina,

Panin,

Volokitin

et al. 2024

Metallurgist

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Microstructure and Mechanical Properties of Metals and Alloys Deformed in Liquid Nitrogen: Review

Cited by 10 publications

References 39 publications

Determining the influence exerted by the static conditions of final squeezing on the compaction process of iron-based powder materials

Determining the influence exerted by the static conditions of final squeezing on the compaction process of iron-based powder materials

Structure and Mechanical Properties of Titanium Processed by Twist Extrusion and Subsequent Rolling

Analysis of the effect of cryogenic cooling during drawing on AISI-316 steel wire properties

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