Overview of Multi-Scale Simulation Techniques for Three Typical Steel Manufacturing Processes.

Steel products typically undergo intricate manufacturing processes, commencing from the liquid phase, with casting, hot rolling, and laminar cooling being among the most crucial processes. In the background of carbon neutrality, thin-slab casting and direct rolling (TSCR) technology has attracted significant attention, which integrates the above three processes into a simpler and more energy-efficient sequence compared to conventional methods. Multi-scale computational modeling and simulation play a crucial role in steel design and optimization, enabling the prediction of properties and microstructure in final steel products. This approach significantly reduces the time and cost of production compared to traditional trial-and-error methodologies. This study provides a review of cross-scale simulations focusing on the casting, hot-rolling, and laminar cooling processes, aiming at presenting the key techniques for realizing cross-scale simulation of the TSCR process.

CISD2 regulates oxidative stress and mitophagy to maintain the balance of the follicular microenvironment in PCOS.

OBJECTIVES: To observe the CISD2 expression among PCOS patients and to explore its profound impact on the follicular microenvironment. Moreover, we want to elucidate the intricate mechanistic contribution of CISD2 to the onset and progression of PCOS. METHODS: Oxidase NOX2, mitophagy-related proteins, and CISD2 were detected by WB. The changes in mitochondrial structure and quantity were observed by transmission electron microscopy. Mitochondrial and lysosome colocalization was used to detect the changes of mitophagy. MDA kit, GSH and GSSG Assay kit and ROS probe were used to detect oxidative stress damage. RESULTS: We found that CISD2, mitophagy and oxidase in the GCs of PCOS patients were significantly increased. Testosterone stimulation leads to the increase of oxidase, mitophagy, and CISD2 in KGN cells. CISD2 inhibition promoted the increase of mitophagy, and the activation of mitochondria-lysosome binding, while alleviating the oxidative stress. CONCLUSIONS: Inhibition of CISD2 can improve the occurrence of oxidative stress by increasing the level of mitophagy, thus affecting the occurrence and development of PCOS diseases.

Endoplasmic reticulum stress-mediated ferroptosis in granulosa cells contributes to follicular dysfunction of polycystic ovary syndrome driven by hyperandrogenism.

RESEARCH QUESTION: Does hyperandrogenaemia affect the function of ovarian granulosa cells by activating ferroptosis, and could this process be regulated by endoplasmic reticulum stress? DESIGN: Levels of ferroptosis and endoplasmic reticulum stress in granulosa cells were detected in women with and without polycystic ovary syndrome (PCOS) undergoing IVF. Ferroptosis and endoplasmic reticulum stress levels of ovarian tissue and follicle development were detected in control mice and PCOS-like mice models, induced by dehydroepiandrosterone. An in-vitro PCOS model of KGN cells was constructed with testosterone and ferroptosis inhibitor Fer-1. Endoplasmic reticulum stress inhibitor, tauroursodeoxycholate (TUDCA), determined the potential mechanism associated with excessive induction of ferroptosis in granulosa cells related to PCOS, and levels of ferroptosis and endoplasmic reticulum stress were detected. RESULTS: Activation of ferroptosis and endoplasmic reticulum stress occurred in granulosa cells of women with PCOS and the varies of PCOS-like mice. The findings in KGN cells demonstrated that testosterone treatment results in elevation of oxidative stress levels, particularly lipid peroxidation, and intracellular iron accumulation in granulosa cells. The expression of genes and proteins associated with factors related to ferroptosis, mitochondrial membrane potential and ultrastructure showed that testosterone activated ferroptosis, whereas Fer-1 reversed these alterations. During in-vitro experiments, activation of endoplasmic reticulum stress induced by testosterone treatment was detected in granulosa cells. In granulosa cells, TUDCA, an inhibitor of endoplasmic reticulum stress, significantly mitigated testosterone-induced ferroptosis. CONCLUSIONS: Ferroptosis plays a part in reproductive injury mediated by hyperandrogens associated with PCOS, and may be regulated by endoplasmic reticulum stress.

Hematopoietic stem and progenitor cell membrane-coated vesicles for bone marrow-targeted leukaemia drug delivery.

Leukemia is a kind of hematological malignancy originating from bone marrow, which provides essential signals for initiation, progression, and recurrence of leukemia. However, how to specifically deliver drugs to the bone marrow remains elusive. Here, we develop biomimetic vesicles by infusing hematopoietic stem and progenitor cell (HSPC) membrane with liposomes (HSPC liposomes), which migrate to the bone marrow of leukemic mice via hyaluronic acid-CD44 axis. Moreover, the biomimetic vesicles exhibit superior binding affinity to leukemia cells through intercellular cell adhesion molecule-1 (ICAM-1)/integrin ß2 (ITGB2) interaction. Further experiments validate that the vesicles carrying chemotherapy drug cytarabine (Ara-C@HSPC-Lipo) markedly inhibit proliferation, induce apoptosis and differentiation of leukemia cells, and decrease number of leukemia stem cells. Mechanically, RNA-seq reveals that Ara-C@HSPC-Lipo treatment induces apoptosis and differentiation and inhibits the oncogenic pathways. Finally, we verify that HSPC liposomes are safe in mice. This study provides a method for targeting bone marrow and treating leukemia.

Elastic strain-induced amorphization in high-entropy alloys.

Elastic stability is the basis for understanding structural responses to external stimuli in crystalline solids, including melting, incipient plasticity and fracture. In this work, elastic stability is investigated in a series of high-entropy alloys (HEAs) using in situ mechanical tests and atomic-resolution characterization in transmission electron microscopy. Under tensile loading, the HEA lattices are observed to undergo a sudden loss of ordering as the elastic strain reached ∽ 10%. Such elastic strain-induced amorphization stands in intrinsic contrast to previously reported dislocation-mediated elastic instability and defect accumulation-mediated amorphization, introducing a form of elastic instability. Together with the first principle calculations and atomic-resolution chemical mapping, we identify that the elastic strain-induced amorphization is closely related to the depressed dislocation nucleation due to the local atomic environment inhomogeneity of HEAs. Our findings provide insights for the understanding of the fundamental nature of physical mechanical phenomena like elastic instability and incipient plasticity.

Lyophilizable Stem Cell-Hybrid Liposome with Long-Term Stability and High Targeting Capacity.

The hybridization of liposome with stem cell membranes is an emerging technology to prepare the nanovehicle with the capacity of disease-responsive targeting. However, the long-term storage of this hybrid liposome has received limited attention in the literature, which is essential for its potential applicability in the clinic. Therefore, the preservation of long-term activity of stem cell-hybrid liposome using freeze-drying is investigated in the present study. Mesenchymal stem cell-hybrid liposome is synthesized and its feasibility for freeze-drying under different conditions is examined. Results reveal that pre-freezing the hybrid liposome at -20 °C in Tris buffer solution (pH 7.4) containing 10% trehalose can well preserve the liposomal structure for at least three months. Notably, major membrane proteins on the hybrid liposome are protected in this formulation and CXCR4-associated targeting capacity is maintained both in vitro and in vivo. Consequently, the hybrid liposome stored for three months demonstrates a comparable tumor inhibition as the fresh-prepared one. The present study provides the first insights into the long-term storage of stem cell hybrid liposome using lyophilization, which may make an important step forward in enhancing the long-term stability of these promising biomimetic nanovehicle and ease the logistics and the freeze-storage in the potential clinical applications.

Partial root-zone drying subsurface drip irrigation increased the alfalfa quality yield but decreased the alfalfa quality content.

Water shortage seriously restricts the development of grassland agriculture in arid land and dramatically impacts alfalfa (Medicago sativa L.) quality content and hay yield. Reasonable irrigation methods have the potential to enhance the alfalfa quality content, hay yield, and thus quality yield. Whether partial root-zone drying subsurface drip irrigation (PRDSDI) improves the alfalfa quality yield, quality content, and hay yield is still unknown compared with conventional subsurface drip irrigation (CSDI). The effects of PRDSDI compared with that of CSDI and the interaction with irrigation volume (10 mm/week, 20 mm/week, and 30 mm/week) on the alfalfa quality yield were investigated in 2017-2018 and explained the change in quality yield with the alfalfa quality content and hay yield. Here, the results showed that PRDSDI did not increase the alfalfa quality yield in 2 years. PRDSDI significantly increased acid detergent fiber by 13.3% and 12.2% in 2018 with 10-mm and 20-mm irrigation volumes and neutral detergent fiber by 16.2%, 13.2%, and 12.6% in 2017 with 10-mm, 20-mm, and 30-mm irrigation volumes, respectively. PRDSDI significantly decreased the crude protein by 5.4% and 8.4% in 2018 with 10-mm and 20-mm irrigation volumes and relative feed value by 15.0% with 20-mm irrigation volume in 2017 and 9.8% with 10-mm irrigation volume in 2018, respectively. In addition, PRDSDI significantly increased the alfalfa average hay yield by 49.5% and 59.6% with 10-mm and 20-mm irrigation volumes in 2018, respectively. Our results provide a counterexample for PRDSDI to improve crop quality. Although there was no significant improvement in average quality yield by PRDSDI, the positive impact of average hay yield on quality yield outweighed the negative impact of quality content. Thus, it has the potential to improve quality yields. The novel findings regarding the effects of PRDSDI on quality yield are potentially favorable for the forage feed value in water-limited areas.

Targeting cancer-associated fibroblast autophagy renders pancreatic cancer eradicable with immunochemotherapy by inhibiting adaptive immune resistance.

Accumulating evidence suggests that cancer-associated fibroblast (CAF) macroautophagy/autophagy is crucial in tumor development and may be a therapeutic target for pancreatic ductal adenocarcinoma (PDAC). However, the role of CAF autophagy during immune surveillance and cancer immunotherapy is unclear. The present study revealed that the inhibition of CAF autophagy suppresses in vivo tumor development in immune-deficient xenografts. This deletion compromises anti-tumor immunity and anti-tumor efficacy both in vitro and in vivo by upregulating CD274/PDL1 levels in an immune-competent mouse model. A block in CAF autophagy reduced the production of IL6 (interleukin 6), disrupting high desmoplastic TME and decreasing USP14 expression at the transcription level in pancreatic cancer cells. We further identify USP14 as the post-translational factor responsible for downregulating CD274 expression by removing K63 linked-ubiquitination at the K280 residue. Finally, chloroquine diphosphate-loaded mesenchymal stem cell (MSC)-liposomes, by accurately targeting CAFs, inhibited CAF autophagy, improving the efficacy of immunochemotherapy to combat pancreatic cancer.Abbreviation: AIR: adaptive immune resistance; ATRA: all-trans-retinoicacid; CAF: cancer-associated fibroblast; CD274/PDL1: CD274 molecule; CM: conditioned medium; CQ: chloroquine diphosphate; CyTOF: Mass cytometry; FGF2/bFGF: fibroblast growth factor 2; ICB: immune checkpoint blockade; IF: immunofluorescence; IHC: immunohistochemistry; IP: immunoprecipitation; MS: mass spectrometer; MSC: mesenchymal stem cell; PDAC: pancreatic ductal adenocarcinoma; TEM: transmission electron microscopy; TILs: tumor infiltrating lymphocytes; TME: tumor microenvironment; USP14: ubiquitin specific peptidase 14.

Correlation between ovarian follicular development and Hippo pathway in polycystic ovary syndrome.

BACKGROUND: For women of childbearing age, the biggest problem caused by polycystic ovary syndrome (PCOS) is infertility, which is mainly caused by anovulation, abnormal follicular development, proliferation of small antral follicles, and cystic follicles. The mechanism underlying its occurrence is not clear. The abnormal proliferation and development of follicles in PCOS patients is a complex process, which is affected by many factors. The objective of this study was to investigate the relationship between the Hippo pathway and follicular development in PCOS, and to further explore this relationship by using the YAP inhibitor verteporfin (VP). METHOD: 30 3-week-old BALB/C female rats were randomly divided into control group (n = 10), DHEA group (n = 10) and DHEA + VP group (n = 10). The morphology of ovary and the degree of follicular development were observed by HE staining, and the expression and location of AMH in ovarian follicles were observed by immunofluorescence. The ovarian reserve function index AMH, cell proliferation index PCNA and the ratio of Hippo pathway related proteins MST, LATS, YAP, P-YAP and P-YAP/YAP were detected by Western blot. RESULTS: After dividing 30 3-week-old female mice into control, dehydroepiandrosterone (DHEA; model of PCOS), and DHEA + VP groups, we found that the number of small follicles increased in the DHEA group compared to the control group. Additionally, in the DHEA group compared to the control group, anti-müllerian hormone (AMH; ovarian reserve index) increased, proliferating cell nuclear antigen (PCNA; cell proliferation index) decreased, and upstream (MST and LATS) and downstream (YAP and p-YAP) proteins in the Hippo pathway increased, though the p-YAP/YAP ratio decreased. VP ameliorated the increases in AMH, MST, LATS, YAP and p-YAP, but did not ameliorate the decrease in the p-YAP/YAP ratio. CONCLUSIONS: This study indicates that the increased small follicles in the ovaries and changes in ovarian reserve and cell proliferation may be closely related to Hippo pathway activation. This suggests that the Hippo pathway may be an important pathway affecting the proliferation and development of follicles and the occurrence of PCOS.

Single-cell characterization of deformation and dynamics of mesenchymal stem cells in microfluidic systems: A computational study.

Understanding the homing dynamics of individual mesenchymal stem cells (MSCs) in physiologically relevant microenvironments is crucial for improving the efficacy of MSC-based therapies for therapeutic and targeting purposes. This study investigates the passive homing behavior of individual MSCs in micropores that mimic interendothelial clefts through predictive computational simulations informed by previous microfluidic experiments. Initially, we quantified the size-dependent behavior of MSCs in micropores and elucidated the underlying mechanisms. Subsequently, we analyzed the shape deformation and traversal dynamics of each MSC. In addition, we conducted a systematic investigation to understand how the mechanical properties of MSCs impact their traversal process. We considered geometric and mechanical parameters, such as reduced cell volume, cell-to-nucleus diameter ratio, and cytoskeletal prestress states. Furthermore, we quantified the changes in the MSC traversal process and identified the quantitative limits in their response to variations in micropore length. Taken together, the computational results indicate the complex dynamic behavior of individual MSCs in the confined microflow. This finding offers an objective way to evaluate the homing ability of MSCs in an interendothelial-slit-like microenvironment.

Hyperandrogenism drives ovarian inflammation and pyroptosis: A possible pathogenesis of PCOS follicular dysplasia.

Hyperandrogenemia and persistent chronic inflammation, two main striking features of polycystic ovary syndrome (PCOS), have been proven involved in follicular dysgenesis in PCOS. However, the association between hyperandrogenism and inflammation activation in PCOS is not fully understood. Excess testosterone（T） induces inflammation and pyroptosis activation in a mouse model of PCOS, leading to ovarian dysfunction and fibrosis. Excessive endoplasmic reticulum (ER) stress is present in ovarian granulosa cells (GCs), testosterone-induced PCOS mouse and cellular models. This study found higher levels of interleukin (IL)-1ß, IL-8, IL-17, and IL-18 in the follicular fluid of PCOS patients with hyperandrogenemia undergoing IVF treatment. In addition, pyroptosis in GCs was demonstrated, which was significantly elevated in PCOS patients. To clarify the association of hyperandrogenism, inflammation, and pyroptosis activation in PCOS, dehydroepiandrosterone(DHEA)-treated mouse PCOS model and T-treated KGN cell line were explored for PCOS mechanism. Markers of inflammatory activation and pyroptosis were significantly increased after DHEA treatment in mice and T treatment in KGN cells. In addition, ER stress sensor proteins were increased simultaneously. However, suppression of inflammation by genipin(GP) led to decreased pyroptosis in KGN cells but no variation in ER stress sensor proteins. In contrast, when treated with tauroursodeoxycholic acid(TUDCA) to attenuate ER stress, the markers of inflammatory factors were significantly reduced, accompanied by a reduction in pyroptosis. Our results suggest that persistent hyperandrogenemia of PCOS promotes local inflammatory activation of the ovary, and the imbalanced inflammatory microenvironment leads to pyroptosis of GCs, which is mediated by ER stress activation.

Machine Learning-Assisted Low-Dimensional Electrocatalysts Design for Hydrogen Evolution Reaction.

Efficient electrocatalysts are crucial for hydrogen generation from electrolyzing water. Nevertheless, the conventional "trial and error" method for producing advanced electrocatalysts is not only cost-ineffective but also time-consuming and labor-intensive. Fortunately, the advancement of machine learning brings new opportunities for electrocatalysts discovery and design. By analyzing experimental and theoretical data, machine learning can effectively predict their hydrogen evolution reaction (HER) performance. This review summarizes recent developments in machine learning for low-dimensional electrocatalysts, including zero-dimension nanoparticles and nanoclusters, one-dimensional nanotubes and nanowires, two-dimensional nanosheets, as well as other electrocatalysts. In particular, the effects of descriptors and algorithms on screening low-dimensional electrocatalysts and investigating their HER performance are highlighted. Finally, the future directions and perspectives for machine learning in electrocatalysis are discussed, emphasizing the potential for machine learning to accelerate electrocatalyst discovery, optimize their performance, and provide new insights into electrocatalytic mechanisms. Overall, this work offers an in-depth understanding of the current state of machine learning in electrocatalysis and its potential for future research.

Unraveling the Atomic Shuffles of Twinning Nucleation in Hexagonal Close-Packed Rhenium Nanocrystals.

Reining in deformation twinning is crucial for the mechanical properties of hexagonal close-packed (HCP) metals and hinges on an explicit understanding of the twinning nucleation mechanism. Unfortunately, it is often suggested rather than conclusively demonstrated that twinning nucleation can be mediated by pure atomic shuffles. Herein, by utilizing in situ high-resolution transmission electron microscopy, we have dissected the atomic shuffling mechanism during the {101̅2} twinning nucleation in rhenium nanocrystals, which revealed the emergence of an intermediate body-centered tetragonal (BCT) structure. Specifically, the double-layered prismatic planes initially shuffle into single-layered {11̅0}BCT planes; subsequently, adjacent {22̅0}BCT planes shuffle in opposite directions to form the basal planes of the twin embryo. This shuffling mechanism is further corroborated by molecular dynamic simulations. The finding provides direct evidence of shuffle-dominated twinning nucleation with atomic details that may lead to better control of this critical twinning mode in HCP metals.

Cell membrane-based biomimetic vehicles for effective central nervous system target delivery: Insights and challenges.

Central nervous system (CNS) disorders, including brain tumor, ischemic stroke, Alzheimer's disease, and Parkinson's disease, threaten human health. And the existence of the blood-brain barrier (BBB) hinders the delivery of drugs and the design of drug targeting delivery vehicles. Over the past decades, great interest has been given to cell membrane-based biomimetic vehicles since the rise of targeting drug delivery systems and biomimetic nanotechnology. Cell membranes are regarded as natural multifunction biomaterials, and provide potential for targeting delivery design and modification. Cell membrane-based biomimetic vehicles appear timely with the participation of cell membranes and nanoparticles, and raises new lights for BBB recognition and transport, and effective therapy with its biological multifunction and high biocompatibility. This review summarizes existing challenges in CNS target delivery and recent advances of different kinds of cell membrane-based biomimetic vehicles for effective CNS target delivery, and deliberates the BBB targeting mechanism. It also discusses the challenges and possibility of clinical translation, and presents new insights for development.

Plastic bottles for chilled carbonated beverages as a source of microplastics and nanoplastics.

Carbonated beverages are characterized by low temperatures, multiple microbubbles, high pressure, and an acidic environment, creating ideal conditions for releasing contaminants from plastic bottles. However, the release patterns of microplastics (MPs) and nanoplastics (NPs) are poorly understood. We investigated the effects of plastic type, CO2 filling volume, temperature, sugar content, and additive on the leakage of MPs/NPs and heavy metals. Our results showed that polypropylene bottles released greater MPs (234±9.66 particles/L) and NPs (9.21±0.73 × 107 particles/L) than polyethylene and polyethylene terephthalate bottles. However, subjecting the plastic bottles to 3 repeated inflation treatments resulted in 91.65-93.18% removal of MPs/NPs. The release of MPs/NPs increased with increasing CO2 filling volume, driven by the synergistic effect of CO2 bubbles and pressure. After 4 freeze-thaw cycles, the release of MPs and NPs significantly increased, reaching 450±38.65 MPs and 2.91±0.10 × 108 NPs per liter, respectively. The presence of sugar leads to an elevation in MPs release compared to sucrose-free carbonated water, while the addition of additives to carbonated water exhibits negligible effects on MPs release. Interestingly, actual carbonated beverages demonstrated higher MPs concentrations (260.52±27.18-281.38±61.33 particles/L) than those observed in our well-controlled experimental setup. Our study highlights the non-negligible risk of MPs/NPs in carbonated beverages at low temperatures and suggests strategies to mitigate human ingestion of MPs/NPs, such as selecting appropriate plastic materials, high-pressure carbonated water pretreatment, and minimizing freeze-thaw cycles. Our findings provide insights for further study of the release patterns of the contaminants in natural environments with bubbles, pressure, low temperature, and freeze-thaw conditions.

Multi-Scale Microstructural Tailoring and Associated Properties of Press-Hardened Steels: A Review.

High-strength press-hardened steels (PHS) are highly desired in the automotive industry to meet the requirement of carbon neutrality. This review aims to provide a systematic study of the relationship between multi-scale microstructural tailoring and the mechanical behavior and other service performance of PHS. It begins with a brief introduction to the background of PHS, followed by an in-depth description of the strategies used to enhance their properties. These strategies are categorized into traditional Mn-B steels and novel PHS. For traditional Mn-B steels, extensive research has verified that the addition of microalloying elements can refine the microstructure of PHS, resulting in improved mechanical properties, hydrogen embrittlement resistance, and other service performance. In the case of novel PHS, recent progress has principally demonstrated that the novel composition of steels coupling with innovative thermomechanical processing can obtain multi-phase structure and superior mechanical properties compared with traditional Mn-B steels, and their effect on oxidation resistance is highlighted. Finally, the review offers an outlook on the future development of PHS from the perspective of academic research and industrial applications.

High Targeting Specificity toward Pulmonary Inflammation Using Mesenchymal Stem Cell-Hybrid Nanovehicle for an Efficient Inflammation Intervention.

Pulmonary inflammation is one of the most reported tissue inflammations in clinic. Successful suppression of inflammation is vital to prevent further inevitably fatal lung degeneration. Glucocorticoid hormone, such as methylprednisolone (MP), is the most applied strategy to control the inflammatory progression yet faces the challenge of systemic side effects caused by the requirement of large-dosage and frequent administration. Highly efficient delivery of MP specifically targeted to inflammatory lung sites may overcome this challenge. Therefore, the present study develops an inflammation-targeted biomimetic nanovehicle, which hybridizes the cell membrane of mesenchymal stem cell with liposome, named as MSCsome. This hybrid nanovehicle shows the ability of high targeting specificity toward inflamed lung cells, due to both the good lung endothelium penetration and the high uptake by inflamed lung cells. Consequently, a single-dose administration of this MP-loaded hybrid nanovehicle achieves a prominent treatment of lipopolysaccharide-induced lung inflammation, and negligible treatment-induced side effects are observed. The present study provides a powerful inflammation-targeted nanovehicle using biomimetic strategy to solve the current challenges of targeted inflammation intervention.

The Characteristic Microstructures and Properties of Steel-Based Alloy via Additive Manufacturing.

Differing from metal alloys produced by conventional techniques, metallic products prepared by additive manufacturing experience distinct solidification thermal histories and solid-state phase transformation processes, resulting in unique microstructures and superior performance. This review starts with commonly used additive manufacturing techniques in steel-based alloy and then some typical microstructures produced by metal additive manufacturing technologies with different components and processes are summarized, including porosity, dislocation cells, dendrite structures, residual stress, element segregation, etc. The characteristic microstructures may exert a significant influence on the properties of additively manufactured products, and thus it is important to tune the components and additive manufacturing process parameters to achieve the desired microstructures. Finally, the future development and prospects of additive manufacturing technology in steel are discussed.

Study on Corrosion Behavior and Mechanism of Ultrahigh-Strength Hot-Stamping Steel Based on Traditional and Compact Strip-Production Processes.

Hot-stamping steel is a type of high-strength steel that is mainly used in key safety components such as the front and rear bumpers, A-pillars, and B-pillars of vehicles. There are two methods of producing hot-stamping steel, i.e., the traditional process and the near net shape of compact strip production (CSP) process. To assess the potential risks of producing hot-stamping steel using CSP, the microstructure and mechanical properties, and especially the corrosion behavior were focused on between the traditional and CSP processes. The original microstructure of hot-stamping steel produced by the traditional process and the CSP process is different. After quenching, the microstructures transform into full martensite, and their mechanical properties meet the 1500 MPa grade. Corrosion tests showed that the faster the quenching speeds, the smaller the corrosion rate of the steel. The corrosion current density changes from 15 to 8.6 µA·cm-2. The corrosion resistance of hot-stamping steel produced by the CSP process is slightly better than that of traditional processes, mainly since the inclusion size and distribution density of CSP-produced steel were both smaller than those of the traditional process. The reduction of inclusions reduces the number of corrosion sites and improves the corrosion resistance of steel.

Phase Transformation Behaviors of Medium Carbon Steels Produced by Twin Roll Casting and Compact Strip Production Processes.

Medium carbon steels have been widely used in the fields of tool and die manufacturing due to their outstanding hardness and wear resistance. In this study, microstructures of 50# steel strips fabricated by twin roll casting (TRC) and compact strip production (CSP) processes were analyzed to investigate the influences of solidification cooling rate, rolling reduction, and coiling temperature on composition segregation, decarburization, and pearlitic phase transformation. The results show that a partial decarburization layer with a thickness of 13.3 µm and banded C-Mn segregation were observed in the 50# steel produced by CSP, leading to the banded distributions of ferrite and pearlite in the C-Mn poor regions and C-Mn rich regions, respectively. For the steel fabricated by TRC, owing to the sub-rapid solidification cooling rate and short processing time at high temperatures, neither apparent C-Mn segregation nor decarburization was observed. In addition, the steel strip fabricated by TRC has higher pearlite volume fractions, larger pearlite nodule sizes, smaller pearlite colony sizes and interlamellar spacings due to the co-influence of larger prior austenite grain size and lower coiling temperatures. The alleviated segregation, eliminated decarburization and large volume fraction of pearlite render TRC a promising process for medium carbon steel production.