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This paper systematically investigates the influence of varying carbon contents on the microstructure and properties of nitrogen-containing Cr13-type corrosion-resistant die steel in quenched and tempered states. The results indicate that the steel microstructure after quenching at 1030 °C mainly consists of martensite and undissolved carbides. As carbon content increases, martensite morphology gradually transitions from lath to cryptocrystalline martensite, accompanied by reduced grain size, and undissolved M₂₃C₆ carbides maintain constant size but increase in quantity. Elevated carbon content raises steel hardness from 50.8 to 56.3 HRC, reduces toughness from 5.4 to 4.4 J, causes brittle fracture of all specimens under impact loading, and degrades pitting corrosion resistance. During 600 °C tempering, numerous nanoscale M₂₃C₆ carbides precipitate. With carbon content increasing from 0.15% to 0.19%, tensile strength rises from 993 to 1047 MPa; further increases to 0.24% reduce it to 1032 MPa. Meanwhile, toughness continuously declines from 12 to 7.5 J. Correspondingly, the fracture mode shifts from purely ductile to mixed ductile-brittle. Owing to the synergistic effects of carbon and nitrogen, the steel with 0.19% carbon content exhibits superior mechanical properties at a fixed nitrogen content of 0.1%

Inconel 617 (IN617) is a nickel-based superalloy with excellent high-temperature properties and corrosion resistance needed for high-temperature gas-cooled small modular reactors. In this study, IN617 parts were fabricated by laser-beam powder bed fusion (PBF-LB) and laser-beam directed energy deposition (DED-LB) additive manufacturing (AM) processes using various process parameters. The coefficient of thermal expansion (CTE) of AM samples was measured using the push-rod dilatometry method up to 1100°C and high-temperature 2D X-ray diffraction experiments up to 900°C. At temperatures below 200°C, the samples showed a non-uniform variation in the CTE due to the presence of lack-of-fusion pores. At temperatures above 800°C, there was a uniform increase in CTE for the samples fabricated with a medium-energy input. The PBF-LB sample showed a CTE of 16.04 × 10⁻⁶ 1/°C, while the DED-LB sample had a CTE of 16.56 × 10⁻⁶ 1/°C at 1000°C. This difference in CTE is likely attributed to the variation in the relative density, with the DED-LB part showing a higher value of 98.44% compared with the PBF-LB part that showed 97.50%. These thermal property data align with the thermal properties of wrought IN617, validating AM as a viable technique for nuclear applications.

The dissolution behavior and kinetics of the (γ + γ′) eutectic microstructure in (backepsilonkappa)151 alloy were systematically studied. A Johnson–Mehl–Avrami–Kolmogorov model was established to predict the variation in the (γ + γ′) eutectic volume fraction during homogenization. The results show that the as-cast microstructure exhibits two distinct (γ + γ′) eutectic morphologies: sunflower-like and blocky. Homogenization treatments were conducted at 1080°C, 1110°C, 1140°C, 1150°C, and 1160°C for different durations to observe the dissolution process. The blocky (γ + γ′) eutectic dissolved much faster than the sunflower-like one. Complete dissolution of the blocky (γ + γ′) eutectic occurred at 1140°C/10 h, while the sunflower-like type required 1160°C/45 h. The dissolution process is mainly controlled by the diffusion of Ti. The dissolution of the sunflower-like eutectic is highly temperature-dependent. At 1150–1160°C, influenced by the elastic strain energy between the γ and eutectic γ′ phases, the eutectic γ′ phase underwent splitting, causing the sunflower-like eutectic to fragment into smaller blocks, which subsequently dissolved. The complete elimination of the (γ + γ′) eutectic microstructure significantly improves the mechanical properties of the alloy, providing a theoretical basis for optimizing the hot-working process of (backepsilonkappa)151 alloy.

Four-point bending fatigue tests were conducted on the L-T (rolling-transverse), L-S (rolling-short transverse), and T-S (transverse-short transverse) planes of an AA2024-T6 alloy plate in air at room temperature, a frequency of 20 Hz, and a stress ratio of R = 0.1. The fatigue limits were 255.7 MPa on the L-T plane, 234.4 MPa on the L-S plane, and 184.8 MPa on the T-S plane, separately. The densities of the crack initiation sites were also measured quantitatively and found to follow a Weibull-type function of the applied maximum cyclic stress with the maximum values of 0.37, 0.93, and 0.15 mm⁻² on the L-T, L-S, and T-S planes respectively. Cracks in the L-T and L-S planes were predominantly initiated at the pre-fractured Fe-containing second-phase particles, while the T-S plane tended to originate at Si-containing particles. Quantitative evaluation of the densities and strength distributions of the fatigue crack initiation sites on different planes of the AA2024-T6 plate revealed the mechanisms for fatigue crack initiation, providing new insights into the anisotropy of fatigue performance of the alloy plate, which might be of value for optimizing alloy design and manufacturing to improve the fatigue properties of the alloy.

This study experimentally investigates the magnetohydrodynamic instability of the bath-metal interface in aluminum reduction cells. A key finding is the instability of a single bichromatic interfacial mode that is characterized by independent longitudinal and transverse wavenumbers, in contrast to previously reported coupled modes, which coexist to become unstable. Interface positions determined from the measurement of anode voltage oscillations are analyzed using Fourier and Hilbert-Huang transforms. Analysis of the reconstructed interface revealed both bichromatic and monochromatic modes. A close match is observed between the experimental mode frequencies and those predicted by the analytical relation reported in our earlier work. The frequencies of (3, 1), (1, 1), and (1, 0) modes come out to be 0.0332 s⁻¹, 0.0780 s⁻¹, and 0.00977 s⁻¹, respectively, from the experiments and 0.0292 s⁻¹, 0.0752 s⁻¹, and 0.00803 s⁻¹ from the analytical relations. Further investigation of interfacial oscillations revealed distinct instability characteristics under different perturbed conditions. The reduction in the height of the upper liquid by a maximum of 10 mm increases the oscillation frequency by a maximum of three times. An increase in oscillation frequency of bichromatic modes was also observed analytically. However, the local perturbation caused by the anode change resulted in the amplification of the low-frequency modes.

This study systematically investigated the effects of electric current aging treatment (EAT) temperature (800–950°C) and duration (1–20 min) on the microstructural evolution and mechanical properties of Co-Cr-Mo alloys. Microstructural analysis revealed that the EAT at 800–950°C for 5 min promotes the precipitation of the ε-Co phase and the growth of carbides (M₂₃C₆ and M₆C). At 950°C, the carbide size and volume fraction increased significantly, reaching 8.9 μm and 6.8 vol.%, respectively. Notably, a lamellar microstructure comprising ε-Co and M₂₃C₆ carbides started to form at 850°C, and the prolonged durations (1 − 20 min) led to a progressive increase in the carbide size and volume fraction. Additionally, the formation of carbides increased the strength of alloys, but it was not conducive to plasticity. The samples treated at 850°C for 1 min exhibited exceptional ultimate tensile strength (830 MPa) and ductility (12.9%), significantly exceeding the performance of some alloys treated by conventional aging methods. These findings demonstrate that EAT is a rapid and effective approach for optimizing the microstructure and mechanical properties of Co-Cr-Mo alloys.

This study addresses the problem of oxygen corrosion in saltwater by developing a binary inhibitor composed of 3,5-diamino-1,2,4-triazole (DTA) and sodium citrate (TSC). The optimal ratio and dosage of DTA to TSC were ascertained using the weight-loss method. The corrosion inhibition efficacy of the DTA-TSC combination was assessed through electrochemical techniques and surface analysis. Additionally, quantum chemical calculations were employed to explore the structure–activity relationship between the inhibitor and the steel surface. Results from the weight-loss experiment suggest an optimal DTA to TSC ratio of 4:1. With a combined dosage of 300 mg/L, the corrosion inhibition rate achieves 90.21%, markedly decreasing the corrosion rate from 0.2393 mm/a to 0.025 mm/a. Electrochemical evaluations indicate that DTA-TSC predominantly suppresses cathodic reactions. Both scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) analyses reveal that DTA-TSC establishes chemical bonds with Fe–N and Fe–O on the steel surface, leading to a notably smoother steel surface. Quantum chemical computations further elucidate that DTA functions as an electron donor, whereas TSC serves as an electron acceptor, both forming chemical bonds with Fe atoms and establishing an adsorption film. In conclusion, the DTA-TSC binary inhibitor proves effective in mitigating the corrosion of A3 carbon steel in oxygenated saltwater.

The integrity and performance of Zr-2.5Nb alloy pressure tubes in nuclear reactors are significantly influenced by the behavior of hydrides within the material. A comprehensive understanding of the hydride distribution, orientation relationship, and precipitation mechanism is crucial for predicting and mitigating potential degradation in these critical components. This study presents a multi-scale characterization approach, integrating scanning electron microscopy, electron backscatter diffraction, and transmission electron microscopy, to investigate the mesoscale, microscale, and atomic-scale features of hydrides in Zr-2.5Nb alloy pressure tubes. The results reveal that hydrides predominantly form along α/α grain boundaries and α/β phase boundaries, with minimal intragranular presence. Distinct crystallographic orientation relationships between interfacial and intragranular hydrides and the α-Zr matrix are identified. Interfacial hydrides (γ-ZrH, δ-ZrH_1.66, and ε-ZrH₂) exhibit a strong hereditary orientation relationship with the α-Zr matrix, characterized by <11(bar{2})0>_α//<110>_γ//<110>_δ//<111>_ε and {0001}_α//{111}_γ//{111}_δ//{101}_ε. Intragranular hydrides maintain the relationship of <11(bar{2})0>_α//<110>_γ//<110>_δ//<110>_ε and {0001}_α//{200}_γ//{200}_δ//{200}_ε. High-resolution transmission electron microscopy observations uncovered a continuous slip of Shockley partial dislocations within the α-matrix, originating from 60° mixed-type <a> perfect dislocations on each basal plane. This slip, coupled with an atomic shuffle mechanism, facilitates the B-type phase transition, leading to the precipitation of δ-ZrH_1.66 with a face-centered cubic structure.

The orientation of both the grain and its neighboring grains significantly impacts the cold-rolled texture for polycrystalline material. The polycrystalline cooperative deformation process is difficult to track in grain-oriented silicon steel with grain sizes on the cm-scale. In this study, the crystal plasticity simulated the Goss grain deformation process with and without taking into account the neighboring grain orientation and the in-grain orientation perturbation. The simulation results indicate that neighboring grains promote the Goss grain rotation to {111}<112> texture, and in-grain orientation perturbation affects the texture distribution in the cold-rolled matrix. The cold-rolled texture of Goss grains demonstrates that neighboring grains and in-grain orientation perturbations lead to a dispersed distribution of the retained Goss texture within the {111}<112> matrix. The remeshing–cropping method allows a continuous reduction in model size and an increase in resolution during the deformation process, enabling a more detailed analysis of texture and dislocation evolution within the substructure. The findings demonstrate that the Goss texture following cold rolling originates from the preserved component of the initial Goss texture and the re-rotation of the {111}<112> matrix towards the Goss texture. The Goss texture exhibits an increased dislocation density at the cold-rolled matrix interface, facilitating the nucleation of Goss grains during the subsequent annealing process. The {111}<112> texture comes from the uniform deformation region, maintaining a uniform texture and low dislocation density throughout the deformation process. In deformation bands, the deformation process leads to an increase in misorientation and dislocation density, resulting in a texture that were composed of Goss, {111}<112>, and transitional textures. Consequently, the deformation band facilitates Goss grain nucleation during the annealing process due to the high dislocation density and retained Goss texture in the band.