Thermal stability of nanogradient microstructure produced by surface mechanical rolling treatment in Zircaloy-4

Xin, Chao; Yang, Dan; Sun, Qiaoyan; Lin, Xin; Sun, Jun

doi:10.1007/s10853-019-04303-z

Cited by 19 publications

(4 citation statements)

References 32 publications

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“…The fatigue strength coefficient is usually related to the tensile strength [12], while the fatigue strength exponent mainly depends on the strain concentration at the crack initiation stage and the stress gradient at the crack propagation stage [31]. The results show that the tensile strength of both the SMGTed and A-SMGTed Zr-4 alloys are higher than that of the CG Zr-4 alloy [29], which leads to an increase in the fatigue strength coefficient (σ f ), as seen in Table 2. The strength exponent (b) is related to cyclic damage during fatigue.…”

Section: Compressive Residual Stressmentioning

confidence: 94%

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Contribution to Improvement of Fatigue Properties of Zr-4 Alloy: Gradient Nanostructured Surface Layer versus Compressive Residual Stress

et al. 2021

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The gradient nanostructured (GNS) layer forms beneath the surface of Zr-4 samples by the surface mechanical grinding treatment (SMGT) process, which increases the fatigue strength apparently due to the synergistic effect of the gradient nanostructured layer and compressive residual stress. The SMGTed Zr-4 samples are subjected to annealing to remove residual stress (A-SMGT) and the individual effect of the GNS layer and compressive residual stress can be clarified. The results show that the gradient nanostructure in the surface is stable after annealing at 400 °C for 2 h but residual stress is apparently removed. Both SMGTed and A-SMGTed Zr-4 samples exhibit higher fatigue strength than that of coarse-grained (CG) Zr-4 alloy. The fatigue fracture of Zr-4 alloy indicates that the hard GNS surface layer hinders fatigue cracks from approaching the surface and leads to a lower fatigue striation space than that of CG Zr-4 samples. The offset fatigue strength of 106 cycles is taken for SMRT-ed, A-SMRT-ed, and CG Zr-4 samples and the results indicate clearly that the GNS surface layer is a key factor for the improvement of fatigue strength of the Zr-4 alloy with surface mechanical grinding treatment.

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Section: Compressive Residual Stressmentioning

confidence: 94%

“…A gradient nanostructure in the surface is stable when the SMGTed Zr-4 sample is heated to 400 • C according to the results of the reference [29]. Therefore, the residual stress can be removed by heating the SMGTed sample to 400 • C without changing the GNS layer.…”

Section: Introductionmentioning

confidence: 99%

Contribution to Improvement of Fatigue Properties of Zr-4 Alloy: Gradient Nanostructured Surface Layer versus Compressive Residual Stress

et al. 2021

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“…However, since the metal ionization flux and plasma density are quite weak in DCMS, the deposited Cr coatings always suffer from problems of coarse and loose columnar structures with many grain boundaries and pinhole defects, which provide direct penetration pathways for corrosive oxygen and hydroxyl ions and cause rapid durability degradation [20][21][22][23]. Increasing the deposition temperature could promote the diffusion of adatoms in parallel with the growth of the coating, reducing the boundary gaps between columnar grains and eliminating the growth defect of the coating [24][25][26], but the longtime deposition for thick coating would substantially deteriorate both the mechanical and chemical properties of zircaloy, due to the stimulated re-crystallization and rapid grain growth [27,28]. An important point of view is that, if one keeps in mind of the structure zone diagram proposed by Anders [29], tailoring the energetic ion flux during the deposition processes offers the most interesting strategy to optimize the coating microstructure and related performance, which has also been also confirmed by Park and Stringer et al [14,30].…”

Section: Introductionmentioning

confidence: 99%

Low-density HiPIMS favored ultrathick and compact chromium coatings on Zircaloy-4 alloys

Zhou,

Zuo,

Chen

et al. 2023

Phys. Scr.

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Protective metallic coatings are receiving increasing attention to modify the anti-corrosion and oxidation resistance of zirconium-based fuel cladding tubes under harsh high-temperature steam/air oxidation conditions. In this work, ultrathick (~20μm) and compact Cr coatings with (001) preferential orientation were deposited on Zircaloy-4 (Zry-4) alloy by high power impulse magnetron sputtering (HiPIMS) technique. The growth characteristics of the Cr coatings were investigated as a function of the discharge plasma species, including Cr+, Cr*, Ar+, and Ar*, which were controlled by the different discharge modes during HiPIMS process. The results showed that, when the discharge feature was changed from the “low voltage direct current magnetron sputtering (DCMS)-like” mode into a “low density HiPIMS” mode, a rapid increase of Cr+ content in the substrate vicinity was obtained by time-integral optical emission spectra (OES), indicating a remarkably enhanced incident energy flux to the deposited Cr coating. The generalized temperature increment of the Cr coating growing surface calculated from the OES, was ~100 K and was mainly affected by the incidence of Cr* atoms. A simplified collision model based on the non-penetrating ions/atoms assumption was also proposed to calculate the transferred energy from the incident energetic species and thus understand the predominant effect of HiPIMS Cr plasma on the achieved nanocrystalline Cr coating with ultra-thick and dense structure, which is still quite challenging for the DCMS deposition process.

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“…Surface microstructure as well as material properties may play an important role in alleviating degradation [1][2][3]. An extreme microstructural approach to improve service performance of components is to fabricate a gradient nanostructured (GNS) rely on considerable plastic deformation, where facilitate grain sizes at the surface layer to reach nano-scale and gradually increase with depth to initial coarse-grained (CG) size [4,5]. In recent years, various processing techniques were adopted to produce GNS layer on metallic surface, like deep rolling [6], shot peening [7], surface mechanical grinding treatment (SMGT) [8], surface mechanical attrition treatment (SMAT) [9], and surface mechanical rolling treatment (SMRT) [5,10].…”

Section: Introductionmentioning

confidence: 99%

Anti-corrosion and corrosive wear properties of AISI 316L stainless steel with surface nanocrystallization by surface mechanical rolling treatment

Shen¹,

Rong²,

Liu³

et al. 2020

Surf. Topogr.: Metrol. Prop.

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In this work, surface mechanical rolling treatment (SMRT) was adopted to obtain the gradient nanostructured (GNS) layer on AISI 316L stainless steel (SS) surface. To evaluate the effect of the GNS, anti-corrosion and corrosive wear tests of the SMRT sample were conducted in pure water and corrosive medium in comparison with a unSMRT (i.e., coarse-grained 316L SS). The corrosion behaviors, tribological properties, damage mechanism as well as relation of pitting and delamination, have been investigated to clarify their synergetic effects and failure mechanism. The results show that, the GNS of 316L SS has poor corrosion resistance due to initiation in local of stress corrosion crack (SCC). However, in comparison with the unSMRT sample, the pitting resistance of 316L SS after SMRT is significantly enhanced. For both samples, the wear loss by delamination is obviously accelerated by corrosion in the friction process. The tribo-corrosion resistance is markedly enhanced with the GNS layer relative to the unSMRT sample, the GNS layer can effectively inhibit the formation of delamination in the corrosive environment, and can also mitigate the abrasive wear in the water lubrication condition, due to the beneficial combination of superfine nanocrystalline structure and high hardness of the GNS layer.

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Thermal stability of nanogradient microstructure produced by surface mechanical rolling treatment in Zircaloy-4

Cited by 19 publications

References 32 publications

Contribution to Improvement of Fatigue Properties of Zr-4 Alloy: Gradient Nanostructured Surface Layer versus Compressive Residual Stress

Contribution to Improvement of Fatigue Properties of Zr-4 Alloy: Gradient Nanostructured Surface Layer versus Compressive Residual Stress

Low-density HiPIMS favored ultrathick and compact chromium coatings on Zircaloy-4 alloys

Anti-corrosion and corrosive wear properties of AISI 316L stainless steel with surface nanocrystallization by surface mechanical rolling treatment

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