Internal Friction in Austenitic Steels

Golovin, S. A.; Belkin, K. N.; Drapkin, B. M.

doi:10.1007/978-1-4899-4725-3_16

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“…The possibility of the superimposition of the impurity relaxation and the strain effect induced by plastic deformation in alloyed austenitic of iron-base alloys has been discussed in [9,[12][13][14]17]. Figure 1 b presents TDIF curves for steel Fe -24.5% Ni -5% Mo hardened for austenite, deformed, and having a low initial carbon content (0.002% C) insufficient for the formation of interstitial atoms in the nearest coordination spheres of the solid solution and the formation of an FR maximum.…”

Section: I~ [In Q~ ' -Q~ I ]-'~ T Q(mentioning

confidence: 99%

“…The changes in the shape of the FR peak due to the appearance of additional maxima in cold plastic defomaation in chromium-nickel and chromium-manganese austenitic steels in the same temperature range are discussed in [9,12,13]. It has been established in a study of TDIF of manganese austenitic steels that the migration of Cottrell and Snoek dislocation atmospheres contributes to the relaxation process under the action of variable stresses in steels with narrow packing defects and the migration of Suzuki atmospheres contributes at wide enough packing defects [13].…”

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Effect of plastic strain on the temperature spectrum of internal friction of austenitic and ferritic steels

et al. 1997

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The present work is devoted to temperature dependences of the internal friction of plastically deformed high-alloy ferritic and austenitic steels with different carbon contents and comparable atomic proportions of dissolved interstitial atoms. The effects of composition, carbon content, degree of plastic strain, and aging temperature and time on the relaxation parameters are investigated. A mechanism for the formation of the spectrum of internal friction in strained steels allowing for the migration of atoms into regions of the crystal lattice activated by the presence of"fresh" dislocations is suggested.Alloy ferrite and austenite steels possess relaxation effects caused by diffusion of single (or paired) dissolved interstitial atoms in the stress field. The corresponding relaxation maxima on the temperature or frequency dependences of the internal friction (IF) are described by the known Debye equation for a standard solid body [1], and the dependence of the relaxation time on the temperature is described by the Arrhenius equationwhere H is the activation energy, k is the Boltzmann constant, and % I is the frequency of atomic jumps at temperature T-~ 0.The frequency of elementary atomic jumps in b.c.c, and f.c.c, metals has the same order. In ferrite alloys based on iron the diffusion of interstitial atoms (Snoek or S-relaxation) is described by -I "c s = 3v = 6w I + 12w2,where v is the'frequency of jumps of interstitial atoms over octahedral interstices, w t is the frequency of jumps at a distance of l/2a, w~ is the frequency of jumps at a distance of (1/,/2) a, and a is the lattice parameter. For atomic jumps of pairs of interstitial atoms in an f.c.c, lattice (the Finkel'-shtein -Rosin or FR relaxation) we havewhere v is the frequency of jumps of pairs of interstitial atoms over octahedral interstices; w r is the frequency of rota-I Tula State University, Tula; Russian State Engineering University, Moscow, Russia.tion of a pair of interstitial atoms, and w d is the frequency of diffusion jumps of individual interstitial atoms. The heights of the S and FR peaks depend differently on the content of interstitial atoms. The degree of FR relaxation and the corresponding internal friction in alloys with an f.c.c, lattice is lower because they are determined not only by the redistribution of interstitial atoms in the stress field but also by the probability of the formation of pairs from them. It should be noted that the relaxation maximum in austenite alloys has been determined for the first time by K. Rosin and B. Finkel'shtein in 1953 [2] and not by Ke and Tsin (1956) as is reported in [ 1 ]. In chromium ferritic [3][4][5][6] and chromium-nickel austenitic steels [2] the corresponding Snoek and Finkelshtein-Rosin maxima are formed on the temperature dependences of internal friction (TDIF) in a close temperature range of 200-300~ at a frequency of about 1 Hz, and their position depends on the content and nature of the alloying elements [3]. Cold plastic deformation causes the formation of new scattering-energy c...

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Section: I~ [In Q~ ' -Q~ I ]-'~ T Q(mentioning

confidence: 99%

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confidence: 99%