Recrystallization and modification of the stainless-steel surface relief under photonic heat load in powerful plasma discharges

Journal Article · Fri Nov 15 00:00:00 EST 2013 · Plasma Physics Reports

DOI:https://doi.org/10.1134/S1063780X13110032· OSTI ID:22216064

Martynenko, Yu. V. ^[1]; Khimchenko, L. N. ^[2]; Zhitlukhin, A. M.; Klimov, N. S. ^[3]; Pitts, R. A. ^[4]; Linke, J. ^[5]; Bazylev, B. ^[6]; Belova, N. E.; Karpov, A. V. ^[1]; Kovalenko, D. V.; Podkovyrov, V. L.; Yaroshevskaya, A. D. ^[3]

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1. National Research Centre Kurchatov Institute (Russian Federation)
2. Project Center ITER (Russian Federation)
3. Troitsk Institute for Innovation and Fusion Research (Russian Federation)
4. ITER Organization (France)
5. EURATOM Association, Forschungszentrum Jülich GmbH (Germany)
6. IHM, Karlsruhe Institute of Technology (Germany)

Targets made of ITER-grade 316L(N)-IG stainless steel and Russian-grade 12Cr18Ni10Ti stainless steel with a close composition were exposed at the QSPA-T plasma gun to plasma photonic radiation pulses simulating conditions of disruption mitigation in ITER. After a large number of pulses, modification of the stainless-steel surface was observed, such as the formation of a wavy structure, irregular roughness, and cracks on the target surface. X-ray and optic microscopic analyses of targets revealed changes in the orientation and dimensions of crystallites (grains) over a depth of up to 20 μm for 316L(N)-IG stainless steel after 200 pulses and up to 40 μm for 12Cr18Ni10Ti stainless steel after 50 pulses, which is significantly larger than the depth of the layer melted in one pulse (∼10 μm). In a series of 200 tests of ITER-grade 316L(N)-IG ITER stainless steel, a linear increase in the height of irregularity (roughness) with increasing number of pulses at a rate of up to ∼1 μm per pulse was observed. No alteration in the chemical composition of the stainless-steel surface in the series of tests was revealed. A model is developed that describes the formation of wavy irregularities on the melted metal surface with allowance for the nonlinear stage of instability of the melted layer with a vapor/plasma flow above it. A decisive factor in this case is the viscous flow of the melted metal from the troughs to tops of the wavy structure. The model predicts saturation of the growth of the wavy structure when its amplitude becomes comparable with its wavelength. Approaches to describing the observed stochastic relief and roughness of the stainless-steel surface formed in the series of tests are considered. The recurrence of the melting-solidification process in which mechanisms of the hill growth compete with the spreading of the material from the hills can result in the formation of a stochastic relief.

• OSTI ID: 22216064
• Journal Information: Plasma Physics Reports, Vol. 39, Issue 11; Other Information: Copyright (c) 2013 Pleiades Publishing, Ltd.; http://www.springer-ny.com; Country of input: International Atomic Energy Agency (IAEA); ISSN 1063-780X
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
CHEMICAL COMPOSITION
COMPARATIVE EVALUATIONS
CRACKS
HEATING LOAD
ITER TOKAMAK
MELTING
METALS
MODIFICATIONS
NONLINEAR PROBLEMS
PLASMA GUNS
PULSES
RECRYSTALLIZATION
ROUGHNESS
STAINLESS STEELS
STOCHASTIC PROCESSES
SURFACES
VAPORS
VISCOUS FLOW
X RADIATION