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The effect of hydrogen content on the deformation and fracture behavior of 27Cr−4Mo−2Ni super ferritic stainless steel (SFSS) was investigated in this study. It was shown that the plasticity and yield strength of SFSS were very susceptible to hydrogen content. The introduction of hydrogen led to a significant decrease in elongation and a concurrent increase in yield strength. Nevertheless, a critical threshold was identified in the elongation reduction, after which the elongation remained approximately constant even with more hydrogen introduced, while the yield strength exhibited a monotonic increase with increasing hydrogen content within the experimental range, attributed to the pinning effect of the hydrogen Cottrell atmosphere on dislocations. Furthermore, the hydrogen-charged SFSS shows an apparent drop in flow stress after upper yielding and a reduced work hardening rate during the subsequent plastic deformation. The more hydrogen is charged, the more the flow stress drops, and the lower the work hardening rate becomes.

During the continuous casting of 430 ferritic stainless steel, the broadening phenomenon and bulging deformation are considered a high-temperature creep. This study investigates 430 ferritic stainless steel by conducting high-temperature uniaxial creep experiments under the temperatures of 0.4-0.5 T m and stresses of 32.5-85 MPa. After creep deformation, the microstructure is analyzed by scanning electron microscopy, energy-dispersive spectroscopy, electron backscatter diffraction, and transmission electron microscopy. The creep curves show the “Normal type.” The creep stress exponent is 3.6-6.7. The creep activation energy is 476.533 kJ/mol. The dislocations climbed over the (Fe, Cr) 23 C 6 are observed. The creep mechanism is dislocations climbing, and the precipitation strengthening contributes to the creep deformation. The recovery and recrystallization are confirmed during the creep deformation. Temperature, not stress, is the main factor in recovery and recrystallization. Numerous voids are observed around the precipitates. There are many dimples on the fracture surface. The creep fracture mechanism belongs to the Transgranular ductile fracture.

In present study, a cold metal transfer process was employed to join Ti-stabilized 439 ferritic stainless steel by using 309 L filler wire with varying heat inputs. The mixed-mode microstructures were recorded in weld zone (WZ) using an optical microscope, whereas chromium-rich peppery structure was formed in the heat-affected zone as validated by scanning electron microscope coupled with energy dispersive spectroscope. The volumetric fractions of austenite and δ -ferrite phases in the WZ were calculated by x-ray diffraction analysis and an increase in heat input resulted in decreased δ -ferrite content. The mechanical properties of both weldments were measured through the micro-hardness and tensile test. The results showed the low heat input (LHI) weldment depicted 15.63 and 7.59% superior micro-hardness and tensile strength, respectively, than its counterpart. However, an opposite trend was observed for intergranular corrosion; the WZ of LHI weldment showed 4% higher degree of sensitization over its counterpart.

The aim of this work is to study the phase transformations, microstructures, and mechanical properties of ferritic stainless steel (FSS) 430 deposits on martensitic stainless steel (MSS) 410 base metal (BM) using laser powder-directed energy deposition (LP-DED) additive manufacturing. The LP-DED additive manufactured FSS 430 deposits on MSS 410 BM underwent post-heat treatment at 815 °C and 980 °C for 1 h, respectively. The analyses of phase transformations and microstructural evolutions of LP-DED FSS 430 on MSS 410 BM were carried out using X-ray diffraction, SEM, and EBSD. The highest strain was observed at the coarsened chromium carbide (Cr23C6) in the joint interface between AM FSS 430 and MSS 410 MB. This contributed to localized lattice distortion and mismatch in crystal structure between chromium carbide and the surrounding ferrite. Tensile strength properties at elevated temperatures were discussed to investigate the effects of the different post-heat treatments. The tensile properties of the as-built samples including tensile strength of about 550 MPa and elongation of about 20%, were the same as those of the commercial FSS 430 material. Tensile properties at 500 °C indicated a modest increase in tensile strength to 540–550 MPa. The specimens heat treated at 980 °C retained higher tensile strength than those heat treated at 815 °C. This would be attributed to the grain refinement from prior LP-DED microstructure and chromium carbide coarsening at higher heat treatment, which can increase dislocation density and yield harder mechanical behavior.

Ferritic stainless steels (FSSs) have attracted considerable attention due to their excellent corrosion resistance and significantly lower cost compared with nickel-bearing austenitic stainless steels. However, the high-temperature wear behavior of additively manufactured FSS 430 has not yet been thoroughly investigated. This study aims to examine the microstructural characteristics and wear properties of laser powder directed energy deposition (LP-DED) FSS 430 fabricated under varying laser powers and hatch distances. Wear testing was conducted at 25 °C and 300 °C after subjecting the samples to solution heat treating at 815 °C and 980 °C for 1 h, followed by forced fan cooling. For comparison, an AISI 430 commercial plate was also tested under the same test conditions. The microstructural evolution and worn surfaces were analyzed using SEM-EDS and EBSD techniques. The wear performance was evaluated based on the friction coefficients and cross-sectional profiles of wear tracks, including wear volume, maximum depth, and scar width. The average friction coefficients (AFCs) of the samples solution heat treated at 980 °C were higher than those treated at 815 °C. Additionally, the AFCs increased with hatch distance at both testing temperatures. A strong correlation was observed between Rockwell hardness and wear resistance, indicating that higher hardness generally results in improved wear performance.

This article addresses the phase evolutions and mechanical properties of dissimilar spot welds formed between AISI 430 stainless steel (FSS) and AISI 321 austenitic stainless steel (ASS). It was revealed that the fusion zone (FZ) microstructure consisted of three phases of ferrite, austenite, and martensite as well as precipitates. The heat-affected zone (HAZ) of 430 FSS had a dual-phase microstructure including coarse ferrite grains and martensite at the ferrite grain boundaries. Also, there are relatively large austenite grains, precipitates, and abundant twins in the HAZ microstructure of 321 ASS. The results of the tensile-shear test showed that peak load and failure energy were increased by enhancing the welding current from 1 to 4 kA. On the other hand, peak load and failure energy were firstly enhanced by an increase in the welding time from 1 to 2 s. Then, the peak load decreased by an enhancement in the welding time from 2 to 3 s. Finally, they improved by increasing the welding time from 3 to 4 s. In addition, it was found that the resistance spot welds failed by the pull-out failure (PF) mode in all welding currents of 1, 2, 3, and 4 kA and all welding times of 1, 2, 3, and 4 s.

Ti 3 SiC 2 ceramic and SUS430 ferritic stainless steel were welded by the transient liquid phase (TLP) diffusion bonding method using an Al interlayer at 850–1050 °C in vacuum. The evolution of phase and morphology at the interface and bonding strength were systematically investigated. The results show that Ti 3 SiC 2 and SUS430 were well bonded at 900–950 °C. Three reaction zones were observed at the interface. At the joint interface area adjacent to alloy, the alloy completely reacted with liquid Al to form Al 86 Fe 14 . At Ti 3 SiC 2 /Al interface, Ti and Si diffused outward from Ti 3 SiC 2 into the molten Al to form Fe 3 Al + Al 5 FeSi + TiAl 3 zone. Adjacent to Ti 3 SiC 2 matrix, Ti 3 Si(Al)C 2  + TiC x zone was formed by the loss of Si. The evolution mechanism of TLP-bonded joints was discussed based on the interface microstructure and product phases. In addition, the tensile strength of the joint increased with increasing bonding temperature. The corresponding maximum value of 59.7 MPa was obtained from SUS430/Al (10 μm)/Ti 3 SiC 2 joint prepared at 950 °C.

This study investigates the forming process (stamping) of bipolar plates which have applied a novel ultra-thin (0.1 mm) super ferritic stainless steel, i.e., SUS470, whose chromium is sufficiently high for corrosion resistance. A three-dimensional finite element model of the stamping process was developed using the commercial software ABAQUS version 2022. The model incorporated optimized die parameters obtained through Central Composite Design (CCD). This model was used to analyze the effects of key forming parameters, including stamping speed and friction coefficient, on the distribution of stress, strain, and thickness reduction during the stamping process. The finite element modeling (FEM) results disclose that the inner corner of the flow channel is a critical defect-prone region, exhibiting stress concentration, uneven strain distribution, and severe thinning. The optimal forming quality can be achieved at a stamping speed of 100 mm/s and a friction coefficient of 0.185 among all varied options. Further, a comparative study of single-stage, conventional two-stage, and optimized two-stage stamping strategies based on previous investigation demonstrates that the optimized two-stage stamping process can effectively alleviate stress and strain concentrations at the corners, significantly reduce thinning problems, and enhance the uniformity and stability during stamping. In summary, this study provides theoretical support for the design of the forming process (stamping) of high-performance super ferritic stainless steel bipolar plates, which is beneficial to subsequent practical engineering application.

Considering that the ferritic stainless steel Z10C13 support plate material in nuclear power equipment tends to undergo fretting wear during service, this paper systematically investigates the effect of varying normal loads (10–50 N) and displacement amplitudes (15–75 μm) on its fretting response and wear mechanisms. Through ball-on-flat fretting wear experiments, together with macro- and micro-scale observations of wear scars, it is revealed that normal load primarily controls the contact intensity and the extent of adhesion, whereas displacement amplitude mainly affects the slip amplitude and features of fatigue damage. The results show that the fretting system’s dissipated energy increases nonlinearly with both load and amplitude, and their coupled effect significantly exacerbates interfacial damage. The wear scar morphology evolves from a shallow bowl shape to a structure characterized by multiple spalling pits and propagating fatigue cracks. An equivalent hardness-corrected Archard model is proposed based on the experimental data. The model captures the nonlinear dependence of equivalent material hardness on both load and amplitude. As a result, it accurately predicts wear volume (R2=0.9838), demonstrating its physical consistency and modeling reliability. Overall, this study elucidates the multi-scale damage evolution mechanism of Z10C13 under fretting conditions and provides a theoretical foundation and methodological support for wear-resistant design, life prediction, and safety evaluation of nuclear power support structures.

In order to investigate the oxidation mechanism of ferritic stainless steel during long-term oxidation at high temperature. The oxidation behavior of Fe-Cr-Ti ferritic stainless steels with 10.38 wt% Cr and 17.41 wt% Cr at 800 °C and 900 °C for 100 h was studied by a constant temperature weight gain method. The morphology and composition of the oxide film were characterized by SEM, EDS and XRD. The experimental results indicate that the oxygen element mainly diffuses inward at 800 °C for two stainless steels, and the oxide film is composed of (Cr1.3Fe0.7)O3 + MnCr2O4. When the temperature rises to 900 °C, metal element mainly diffuses outward, and Fe2O3 outer oxide layer and Fe rich Fe-Cr inner oxide layer are formed in Fe11Cr0.5Ti stainless steel; Cr2O3 + Cr rich M3O4 spinel oxide film is formed in Fe18Cr0.5Ti stainless steel, while the inner layer is composed of SiO2. The main reason for the significant decrease of oxidation resistance of Fe11Cr0.5Ti stainless steel is that the low content of Cr cannot form a Cr rich oxide layer to inhibit the outward diffusion of Fe element, and the stability of oxide film is poor to protect the matrix.