To overcome the industrial limitation of conventional deformation-induced ferrite transformation (DIFT), which is typically restricted to temperatures below 810 degrees C, this study employed Al alloying in an Fe-0.06C-1.5Mn steel. The addition of 1.5 wt % Al reduced the Gibbs free energy difference for the austenite-to-ferrite transformation by approximately 140 J/mol. This reduction effectively lowered the activation barrier for DIFT, significantly destabilized austenite, and successfully induced DIFT within an elevated temperature range of 800-1100 degrees C. Rolling at 1100 degrees C yielded DIFT ferrite grains of approximately 5 mu m with a maximum ferrite fraction of 83 %, while rolling at 800 degrees C with low strain rates produced ultrafine DIFT ferrite of similar to 2.36 mu m. The enrichment of C and Al elements at prior austenite grain boundaries enhances local stability, suppressing boundary nucleation and forcing intragranular nucleation. This new phenomenon can be termed the "Continuous DIFT". This work provides a novel pathway for achieving DIFT at high temperature through Al alloying and developing highstrength-toughness steels.

The environmental conditions determine the long-term conservation of tangible cultural heritage, affecting the processes of physical, chemical, and biological degradation of materials and situations over an extensive spectrum. The last few years have seen expansive gains in sensing technology, data acquisition, and analysis procedures, which have facilitated the creation of intelligent environmental practices that surpass the conventional and unchanging conservation policies. This review presents a recap on existing studies in smart environmental technologies to preserve tangible heritage with a focus on the spectrum between environmental monitoring and intelligent microclimate control, predictive deterioration modelling, and decision support. The paper reviews the main environmental hazards to build, movable, and outdoor heritage sites and outlines how high-resolution surveillance systems, sensor networks, and non-invasive methods deliver the data base of adaptive conservation management. Intelligent microclimate control strategies are studied in the context of the ability to achieve conservation performance, energy efficiency, and sustainability. Special focus is made on predictive deterioration modelling, which can include physics-based, empirical, and data-driven models, and the issues of validation, uncertainty, and interpretability in heritage. The combination of these elements as part of decision support structures is noted as a critical move to preventive and risk-based conservation. Through a critical analysis of the existing capacities and capacities, the review outlines the main gaps in the current research and the way forward in the future of designing resilient, data-infused heritage conservation systems that can address the strategic shifts in the environmental and climatic forces.

The influence of mechanical twinning on mechanical performances of advanced steels remains a central issue in alloy design. In the present work, we systematically investigated the effects of mechanical twinning on tensile ductility and impact toughness in Fe-0.6C-0.5Si-24Mn-0/3/5Al (wt.%) steels. We hence conclude that mechanical twinning is indispensable for achieving outstanding tensile ductility but not a prerequisite for attaining high impact toughness. Notably, high impact toughness can instead be realized through alternative toughening mechanisms, particularly in alloys with elevated stacking fault energy. These findings challenge the prevailing paradigm linking twinning to both ductility and toughness, and offer a new framework for designing highstrength steels with an optimized balance of properties for demanding applications.

As a key component in semiconductor equipment, the mass flow controller (MFC) regulates the gas delivery ratio in the reaction chamber of the equipment, the machining quality of the gas flow channels and seal surfaces in MFC valve also determines the accuracy and service life of the component. In industrial production, these features are often finished manually, which inevitably leads to inconsistent results. This article uses a novel sinter pouring polyurethane (SPPU) grind-polishing tool to process these features, and the tool can be used for automated ultra precision polishing of MFC valve features. Based on the properties of the tool, a theoretical model was established for the chip concentration and polishing force with polishing time during the process. Through experiments, it was found that the main defects of the polished surfaces are deep scratches and pits, and with the increase of feeding velocity, the changes in surface defects under different polishing pressures show completely opposite trends. In addition, it can be observed the relationship between the stability of instantaneous polishing force and the generation of surface defects. The greater the degree of force dispersion, the more obvious the surface defects after processing. This study can provide reference for the automated processing of MFC component.

Pre-strain and aging (PA) treatment is essential in manufacturing Nb3Sn magnets and must be performed together with the outer jacket material. This imposes strict requirements on the aging resistance and cryogenic performance of the jacket material, making it crucial to understand the effects of PA treatment. This study investigates the effect of pre-strain and aging (PA) treatment on Fe-Mn-xAl-C high-Mn austenitic steels for 4 K application, which shows promise for replacing 316LN and JK2LB stainless steels in 4 K applications as a new cryogenic material. The findings reveal that: PA treatment triggers detrimental carbide precipitation in 0Al and 2Al steels, causing embrittlement and reduced ductility. The 5Al steel maintains microstructural stability during PA, achieving a 165 MPa yield strength increase through Taylor lattice and dislocation strengthening. PA alters deformation mechanisms: lower Al steels show enhanced twinning due to reduced SFE, while 5Al steel combines microband- and twinning-induced plasticity. 5Al steel exhibits an excellent combination of yield strength and ductility compared to existing cryogenic materials for 4.2 K applications. The research provides crucial insights into how PA processing manipulates microstructure and cryogenic deformation behaviour, establishing a theoretical foundation for designing advanced cryogenic materials with superior strength-ductility synergy at 4.2 K.

In the realm of high-performance wind power gearboxes, the manufacturing process of 100CrMo7-3 bearing rings is significantly influenced by hot deformation, which is crucial for microstructural refinement. But research on the microstructural evolution during the hot deformation of 100CrMo7-3 bearing steel is sparse. This study utilizes a thermo-mechanical simulator to conduct high-temperature compression tests, enabling the observation of the morphology of the original austenite grain boundaries. We develop a high-temperature flow stress model, a dynamic recrystallization volume fraction model, and an austenite grain size model for 100CrMo7-3 bearing steel, each demonstrating high predictive accuracy. Additionally, we compare the dynamics of austenite dynamic recrystallization in 100CrMo7-3 bearing steel with that of the widely used GCr15 bearing steel. Our findings indicate that the dynamic recrystallization of austenite in 100CrMo7-3 bearing steel is retarded due to the increased content of highly hardenable elements such as Mn and Mo. This research provides essential foundational model parameters for investigating the microstructural evolution and optimizing the hot working process of 100CrMo7-3 bearing steel.

Significantly refining hot-rolled thick gauge steels microstructure to enhance strength and toughness concurrently remains critical. Conventional ferrite dynamic recrystallization (DRX) or deformation-induced ferrite transformation (DIFT) are constrained by requisite low temperatures (< 800 degrees C), hindering industrial application. To overcome this bottleneck, this study elevated the onset temperatures for DRX and DIFT by the addition of 1.5 wt% aluminum. Results demonstrate that aluminum alloying significantly increases the DRX and DIFT temperatures by over 300 degrees C, thereby surpassing conventional processing temperature limitations. The microstructural evolution across different strain stages was systematically analyzed. Quantitative analysis revealed that deformation temperature governs the relative proportions of DIFT, DRX, and dynamic recovery (DRV) by modulating the austenite-ferrite transformation barrier and dislocation mobility. Concurrently, strain rate controls the choice of discontinuous dynamic recrystallization (DDRX) and continuous dynamic recrystallization (CDRX) by influencing nucleation rates and strain distribution. Hot simulation tests confirm that deformation at 900 degrees C with a strain rate of 1 s(-1) to a strain of 0.8 induces DIFT in 40 % of the austenite. Simultaneously, ferrite grain size is remarkably refined from 29 mu m to 5.6 +/- 4.6 mu m, significantly finer than that typically achievable in conventional hot-rolled thick gauge steels (> 15 mu m). This study is the first to achieve significant refinement of the microstructure in low-carbon microalloyed steels under low strain levels (< 0.8) within the temperature range compatible with industrial production processes and acceptable deformation temperatures, filling the gap in the field of microstructure refinement in conventional hot rolling.

The Fe–Mn damping alloys possess considerable damping capacity, but their yield strength is rather low. The 800 MPa Fe–Mn alloy with expected damping capacity was designed by the combination of grain refinement and ε-martensite introduction. The yield strength can be greatly raised to around 700 MPa by refining grain size from 88.4 to 1.8 μm. Although there exist numerous stacking faults in the fine-grained alloy, the damping capacity is strongly deteriorated due to the suppression of thermally activated ε-martensite. We demonstrate that the stacking faults cannot provide effective contribution to damping capacity and hence introduce a considerable volume fraction of stress/strain-induced ε-martensite to raise damping sources, including ε-martensite and γ/ε interfaces, etc., by a small pre-strain. From this, the damping capacity can be improved, and the yield strength can be further enhanced from nearly 700 MPa to around 800 MPa. Thus, the combination of high yield strength and good damping capacity is realized.

High-Mn steels are commonly fabricated by hot rolling and on-line cooling for cryogenic applications, because there exists an aging embrittlement zone in most high-Mn steels, and this shortcoming makes it difficult to optimize their mechanical properties by heat treatments. Hence, 0.6C-18Mn-0/3/5Al (in wt.%) steels were designed to investigate the effects of Al on their strength and toughness. The addition of 5 wt.% Al can increase yield strength from 357 to 461 MPa and the Charpy impact absorbed energy from 56 to 119 J. Although there is still a cryogenic aging embrittlement zone in each steel, we found that the addition of Al can narrow this brittle zone. Moreover, the absorbed energy is lowered by around 89%, 48%, and 40% for the 0Al, 3Al, and 5Al steels at −196 °C, respectively. Additionally, impact plastic deformation mechanisms were also revealed in the steels with a heat-treating temperature of 600 °C, revealing that the main deformation mechanism shifts from numerous partial dislocation slip to twinning plus strong planar slip as the addition of Al increases.

The effect of grain size on corrosion resistance of VCoNi medium entropy alloy (MEA) was investigated via the combination of electrochemical tests and microstructure characterization. The length of special boundaries and LAGBs were increased with the increase in average grain size, but the distribution of high angle grain boundaries decreased gradually. Additionally, the low fraction of GBs attenuate the transport of V elements to the substrate surface, thereby reducing the precipitation of V-rich phases, which has a significant beneficial effect on the corrosion resistance of the alloy. Overall, an increase in grain size improves corrosion resistance of VCoNi MEA.

In our previous work (Powder Technol, 2024, 433, 119276), an approach of inclined bottom blowing has been proposed. It was found that this novel mode of bottom blowing helps to improve the flow characteristics and mixing effect of bath in bottom blowing converters. In this work, the possibility of applying this bottom blowing technique in top and bottom combined blowing converters is investigated. An Euler-Euler model is adopted to describe top and bottom blown process in a simplified model of a 260 t converter. The accuracy of the model is validated by comparing the numerical simulation results with the previously published experimental results. Then, according to the similarity theory, the size of an actual converter is downsized and based on the downsized model a series of numerical simulations are carried out. The influence of bottom blowing angle on the flow characteristics, mixing efficiency and converter wall erosion are discussed in detail. Numerical simulation results show that the mixing time first decreases and then increases with the increase of the bottom blowing angle. When the bottom blowing angle is 5 6 deg, the mixing time of molten pool is the shortest because the flow dynamics in the lower part of the bath are effectively improved by using the 6 deg angle for bottom blowing. The wall shear stress is used to characterize the erosion of the converter wall. The study results show that the most severe area of erosion on the converter wall occurs near the liquid surface in the direction of the top jet. The severity of erosion on the converter wall decreases gradually as the bath depth increases. The wall shear stress changes slightly with the angle, which indicates that the novel bottom blowing approach will not aggravate the wall erosion. Combining with the results in this paper and the factory production demand, the actual industrial converter using the 7 deg bottom blowing angle effectively improve the efficiency of smelting.

In the present work, the medium Mn steel with a strength- ductility product of 49.5 GPa & sdot;% was fabricated by a hot rolling, quenching and intercritical annealing process. The excellent mechanical property is attributed to the heterogeneous austenite morphologies, i.e., lath, granular and equiaxed austenite, and the successive TWIP + TRIP effects. The present work especially focus on two aspects: i) the evolution of micro-strain between different morphologies of austenite and ferrite during tensile deformation and its impact on the strain hardening caused by the transformation induced plasticity (TRIP) effect; and ii) the strengthening mechanisms of successive twin induced plasticity (TWIP) and TRIP effects in heterogeneous structures. Under different austenite/ferrite micro- strain interactions, the sequence of TRIP effect is in granular, lath and equiaxed austenite grains. Prior to this, the TWIP effect mainly enhance the strength of austenite, particularly equiaxed grains, which act as a high-strength skeleton structure, postponing the initiation of necking.

In this study, we developed a medium manganese steel (MMS) with a composition Fe-9.8Mn-0.22C-1.0Si-3.1Al-0.1Nb-0.2V(wt.%), which was processed to obtain a hetero-structured microstructure with a tailored austenite micromorphology. A straightforward processing strategy, consisting of hot rolling followed by intercritical annealing, was employed to significantly enhance synergy between strength and ductility. The mechanical behavior was investigated through interrupted tensile tests and characterized by advanced analytical techniques including electron backscatter diffraction (EBSD), transmission electron microscopy (TEM), transmission Kikuchi diffraction (TKD), and X-ray diffraction (XRD). These investigations confirmed that MMS exhibited both twinning induced plasticity (TWIP) and transformation induced plasticity (TRIP) mechanisms. In the deformation process, TWIP dominated the initial stages while TRIP becomes more prevalent in the later stages. Notably, the presence of a heterogeneous microstructure stabilized and prolongs the TRIP effect, leading to enhanced strain hardening, and consequently, superior strength and ductility. This research presented a novel method for designing hetero-structured microstructures in multiphase steels with metastable austenite, significantly enhancing their mechanical properties. This methodology not only provided deep insights into the alloy design, but also offered practical guidance for industrial applications, emphasizing the simplicity and effectiveness of this processing strategy.

Twin intersections have been reported to significantly impact on macroscopic properties by relaxing localized stress concentration and accommodating strain. Here the atomic-scale structural characterization of the twin intersection region in a deformed high Mn twinning-induced plasticity (TWIP) steel was conducted using high-resolution transmission electron microscopy. Detailed microstructural features were revealed at the twin intersection region, including twin intersection rotation, low angle grain boundary and ε martensite. The twin intersections were observed to preserve the face-centered cubic structure, which exhibiting deviation angles of ∼0-15 o with respect to the barrier twin depending on the localized stress concentration. Interestingly, the ε-martensite was observed in the vicinity of the twin intersection, which shows a wedge shape, distinct from the usual plate-like deformation-induced martensite. Therefore, we identified here a novel stress relaxation mechanism at the twin intersection region. Based on the detailed microstructural characterization of the twin interaction region at the atomic scale, the fundamental dislocation mechanisms of twin transmission and interaction were discussed. The research thus advances the understanding of twin intersection rotation and ε-martensite transformation by twin-twin interactions.

For decades, solid solution strengthening with up to 9 wt.% Ni has been the only successful strategy to obtain high strength and high impact toughness in bcc-structured (ferritic or tempered martensitic) cryogenic steels. Until now coherent nano-precipitates, an effective strengthening agent at room temperature, cannot be used to improve properties at cryogenic temperatures. Here, a new type of Mo-rich nano-B2 precipitates formed in a 6.5 wt.% Ni steel upon doping with 0.2 wt.% of Mo is reported. These precipitates are not only fully coherent with the matrix but are also shearable at 77 K. A high precipitate number density in excess of 2 x 1024 m-3 has been achieved by an industrially feasible process optimization, which brings both the cryogenic strength and impact toughness of the steel to the same levels as those of 9Ni steels. The Mo-rich B2 precipitation strengthening, therefore, opens a new avenue for the design and development of low-cost high-performance cryogenic steels.

The effect of Cu alloying on hydrogen embrittlement (HE) in TWIP steel was studied using the low-speed linearly increasing stress test (LIST) with simultaneous cathodic hydrogen charging. Cu alloying influenced HE resistance by the following mechanism. (i) Cu alloying increased the stacking fault energy, which canceled out the embrittling effect of hydrogen on promoting local plasticity and mechanical twins/dislocations concentration. (ii) Cu alloying refined the austenite grains, especially after low-temperature (700 degrees C) annealing and thus delayed mechanical twinning that causes an increased hydrogen concentration. (iii) Cu alloying caused the formation of a Cu-rich surface which reduced the diffusible hydrogen content, particularly for the steel annealed at 900 degrees C. (iv) Cu alloying dispersed mechanical twins by Cu precipitate/Cu-rich clusters, which homogenized the diffusible hydrogen and decreased the local hydrogen concentration at the HE vulnerable interfaces. Mechanism (iv) in the 700 degrees C annealed Cu-alloyed TWIP steel produced the greatest increase in HE resistance.

Aging treatment is an effective way of strengthening high-Mn strip steels based on auto -motive industry. However, the role of this method in enhancing yield strength and cryo-genic toughness (-196 & DEG;C) of high-Mn steels has still unclear so far. Besides, solute segregation has always been a vital factor affecting the mechanical properties of high-Mn steels, whereas it is still lacking in adequate attention. In the present work, the micro-structural evolution, including solute macrosegregation, grain boundary segregation and precipitation, and the resultant mechanical properties under different aging treatment were elaborated. It was found that the banded segregation of C, Mn and V elements formed during aging treatment strongly affects the cryogenic toughness. Tridimensional EPMA analyses demonstrate that there exists dense banded segregation of C, V and Mn elements in longitudinal section and cross section for both aged steels (aging at 500 & DEG;C and 800 & DEG;C). However, more obvious banded segregation of C and V elements developed in the steel aged at 800 & DEG;C (800A), and more micron-scale VC carbides tend to precipitate at segregation band, which leads to the easy initiation and propagation of microcracks along the segre-gation band. Moreover, numerous nano-scale VC precipitates significantly increase the yield strength of 800A steel by 100 MPa, but there exist severer grain boundary segregation and precipitation after aging treatment, which enhances the twining stress by increasing local SFE of grain boundary regions. The twinning formation hence became harder, further deteriorating the cryogenic toughness of the 800A steel.& COPY; 2023 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

The high-Mn austenitic steel exhibits better fatigue performance at 77 K than at RT. Especially when the stress amplitude is in the range of yield strength (YS) to 1.08YS, the fatigue life decreases slightly at 77 K, while decreases significantly at RT. Lowering the stacking fault energy and increasing the stress amplitude at 77 K promotes twinning, which is responsible for improving the tolerance of fatigue damage and cracking delay. Surprisingly, with the stress amplitude increases to 1.04YS and 1.08YS, migration of twin boundaries and detwinning are observed, respectively, which can enhance the resistance against intergranular fatigue cracking.

There exist urgent demands to develop structural materials with superior mechanical properties at 4.2 K. Some high-entropy steels (HESs) show potentials as cryogenic materials, but their deformation behaviors and mechanical properties at 4.2 K have been rarely investigated. Moreover, the aging-induced embrit-tlement of HESs also severely restricts their applications. In this work, the Fe-Mn-Al-C HESs with different Al contents (0, 4, 10 or 15 at.%) and grain sizes were fabricated, and their deformation behaviors and mechanical properties at 4.2 K were systematically studied. With increasing the Al content, (Fe, Mn)23C6 carbides are effectively inhibited in 10%Al HES after aging at 923 K for 10 days. Therefore, the premature fracture of 10%Al HES is avoided, leading to the excellent combination of high strength (-1.5 GPa) and high fracture toughness (255 MPaGreek ano teleiam1/2) at 4.2 K. The deformation mechanisms shift from the extensive twinning and deformation bands in 0Al HES to the lesser twinning, Taylor lattices and deformation bands in 10%Al HES, which contribute to the high strength and ductility of the 10%Al HES. Furthermore, the 10%Al HES with larger grains displays a much higher fracture toughness at 4.2 K, and this inverse size effect on the cryogenic toughness was elaborately revealed. (c) 2023 Northeastern University. Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).

The high Mn steels are expected to become a novel steel for liquefied natural gas (LNG) tank building because of their low cost, high strength, and excellent low-temperature impact toughness. Up until now, it is still limited for studies on corrosion behavior of high Mn steel in a Cl–-containing environment. We found that strong Mn enrichment layers always exist in the outer rust layer, whereas strong Al enrichment layers always exist in the inner rust layer. However, the Al and Cl simultaneously enrich in the same area. Although the corrosion resistance can be further improved by increasing Al content from 5.0 mass% to 8.0 mass%, the improvement degree becomes weak and the pitting corrosion becomes serious due to the formation of δ-ferrite. There are two aspects to explain why Al improves corrosion resistance. (1) More Al addition can enhance the resistance of passive oxide. (2) The α-FeOOH content can be increased and the compactness of the rust layer can be also enhanced by increasing Al content.