Browse Topic: Ferrous metals

Items (13,041)
G-3, Aerospace Couplings, Fittings, Hose, Tubing Assemblies
G-3, Aerospace Couplings, Fittings, Hose, Tubing Assemblies
The automotive industry's transition towards electrification, particularly in the passenger car (PC) and light commercial vehicle (LCV) segments, has intensified the focus on vehicle lightweighting to maximize battery range and efficiency. Conventional brake systems in electric vehicles (EVs) are subject to minimal mechanical wear due to regenerative braking, making corrosion the primary cause of component failure and replacement. This paper details the development and production of an innovative lightweight brake, which addresses these challenges. The "Cast-In" brake disc combines a traditional gray cast iron friction ring with a pre-finished, deep-drawn steel hat through a specialized composite casting process. This design achieves a significant reduction in unsprung mass—1.6 kg per disc in a 390mm x 36mm example—directly contributing to improved vehicle dynamics and energy efficiency. Key manufacturing challenges, including ensuring a robust material bond, preventing casting defects, and sealing the steel hat during casting, have been overcome through advanced process controls, simulation, and a patented sealing system. Furthermore, a novel, enhanced corrosion protection system has been developed and validated to meet the required service life of over 10 years, addressing the specific demands of e-mobility. With production scheduled to begin in April 2026, this technology is a milestone for modern braking solutions in the era of electrification.
von Reth, Thomas
Ferritic nitrocarburizing (FNC) with in-process post-oxidation has been developed as a production-capable surface engineering solution for gray cast iron (GCI) brake rotors to meet the Euro 7 non-exhaust particulate emission limits. While prior investigations have demonstrated significant PM₁₀ reduction, improved corrosion resistance, and stable braking performance, the influence of FNC on noise, vibration, and harshness (NVH) performance requires systematic evaluation. This study quantified the relative contributions of the alloy composition, rotor geometry, and FNC treatment to the modal frequency and damping behavior. Seven ventilated disc types from multiple foundries were characterized to assess the composition-driven variability. In addition, 120 production discs (ventilated and solid) were measured before and after FNC processing to isolate the treatment effects. Modal properties were obtained using impulse-hammer testing under free–free boundary conditions in accordance with VDA 301, and damping was evaluated using the half-power bandwidth method (Q-factor). The results show that the natural frequency is governed primarily by geometric parameters, scaling with the friction-ring thickness and disc diameter. In contrast, the damping behavior is dominated by the alloy composition and graphite morphology. Variations in silicon, chromium, and carbon equivalent produced a 3–4× difference in the Q-factor across foundries. FNC treatment had a negligible effect on the natural frequency (<1%) but produced a measurable increase in the Q-factor, typically 7–10% for solid discs and 22–32% for ventilated discs. The findings establish a clear hierarchy of influence: composition controls the damping, geometry controls the frequency, and the FNC introduces a secondary shift. Within production-relevant composition windows, FNC + Smart-ONC® does not represent a limiting factor for the NVH performance of Euro 7–compliant brake systems.
Awe, Samuel AyowoleHolly, MikeWinter, Karl-Michael
A unified thermomechanical fatigue (TMF) life-prediction methodology is presented for lamellar graphite (grey) cast iron brake rotors operating under the severe transient thermal loads that arise in brake dynamometer durability testing. The workflow links four ingredients within a single rotor-level framework: transient nonlinear finite-element analysis, temperature-dependent inelastic constitutive modeling, a mechanism-based short-crack TMF damage model, and an elastic-plastic (nonlinear) fracture-mechanics crack-growth simulation. Two constitutive descriptions are exercised for the structural analysis — the standard rate-dependent Chaboche viscoplastic model available in Abaqus, and a user material subroutine (UMAT) that couples Chaboche viscoplasticity with continuum damage in order to reproduce the tension–compression asymmetry of cast iron. The resulting stress, strain, and temperature histories drive a multiaxial thermomechanical fatigue Damage (DTMF) computation that estimates crack initiation and early extension, after which a nonlinear fracture-mechanics procedure simulates crack-front advance toward through-thickness failure. Both constitutive models correctly localize the crack-initiation site on the rotor inner diameter, consistent with the dynamometer observations; for the loading histories examined, the standard Chaboche model yields lives in closer agreement with test. The crack-growth simulation reproduces the rapid post-initiation propagation seen experimentally and resolves branch-wise differences in crack-front evolution through the rotor section.
Lee, HeewookGarcia, ArnoldoLiu, YiHazime, RadwanBoughanmi, HeniKassir, Abdallah
G-3, Aerospace Couplings, Fittings, Hose, Tubing Assemblies
G-3, Aerospace Couplings, Fittings, Hose, Tubing Assemblies
G-3, Aerospace Couplings, Fittings, Hose, Tubing Assemblies
G-3, Aerospace Couplings, Fittings, Hose, Tubing Assemblies
With the rapid development of the transportation industry, heavy-duty traffic has become extremely common, particularly in some coastal port cities where the presence of container terminals leads to generally high vehicle axle loads. In these regions with an advanced transportation industry, large-scale cross-sea bridges are often required to ensure transport efficiency. However, conventional long-span bridge types, such as cable-stayed bridges and suspension bridges, face challenges in meeting the demands of heavy-duty traffic due to limitations imposed by the self-weight of pylons. In response, this paper proposes a prefabricated steel shell–ultra high performance concrete (SS–UHPC) composite pylon composed of basic SS–UHPC units, aiming to enhance both the load-carrying efficiency and seismic performance of the structure. A conceptual design of the SS–UHPC composite pylon was developed based on a super-long-span suspension bridge with a main span of 2180 m, and a comparative analysis was carried out against a conventional steel shell–normal concrete (SS–NC) composite pylon. The results show that, owing to the higher strength-to-self-weight ratio of UHPC, the SS–UHPC composite pylon achieves a 42.4% reduction in self-weight compared to the SS–NC composite pylon. Under the most unfavorable load condition, the axial force and transverse bending moment at the pylon base are reduced by 13.79% and 6.24%, respectively. Under maximum seismic load, the axial force and transverse bending moment at the base decrease by 14.12% and 28.92%, respectively, demonstrating improved load-carrying efficiency and seismic performance of the pylon. Although the life-cycle cost of the SS–UHPC composite pylon is higher than that of the SS–NC composite pylon, its superior mechanical behavior sufficiently offsets the cost difference. In conclusion, the superior mechanical behavior of the SS-UHPC composite pylon makes it better suited for application in long-span bridges subjected to heavy-duty transportation loads.
Chen, Jing LiLiu, Yong JianPeng, Hong BoSun, Li PengYang, Ze Hong
A nonlinear finite element model was applied to study the in-plane instability of steel portal piers, in which initial geometric imperfections, welding residual stresses, and material nonlinearity were considered. The modeling procedure was compared with experimental results from box-section members, and consistent tendencies in load level and deformation evolution were observed. In the numerical analyses, the initial elastic buckling configuration exhibited an in-plane antisymmetric form. As loading continued beyond the elastic range, this deformation pattern persisted. With further loading, the deformation remained purely axial while combining compression with bending. During this stage, plastic hinges appeared near the column tops, while lateral displacement became clearly observable. Comparison models with different geometric proportions show that variations in the span-to-height ratio and the beam–column stiffness ratio influence how instability develops and where plastic deformation tends to localize. From a design perspective, these trends can be considered when distinguishing instability characteristics and selecting stiffness proportions between beams and piers.
Li, JieShangguan, BingCheng, ZhangxuRuan, FurongBai, Fan
Taking the newly constructed Maanshan Yangtze River Highway-Railway Dual-Purpose Bridge — a three-tower steel truss cable-stayed bridge with two main spans of 1120 meters — as the research object, this study systematically explores the influencing factors and evolutionary characteristics of hole wall stability for large-diameter bored piles in thick sand layers. The research results reveal the following mechanisms: with the expansion of pile diameter, the hole wall generates greater deflection, the soil’s internal arch effect is gradually attenuated, soil cohesion decreases, and the plastic zone of the soil surrounding the pile shows a tendency of outward extension, collectively increasing the susceptibility to hole collapse. To maintain hole wall stability, the resultant force of the internal circular arch support and mud pressure must exceed or equal the total lateral pressure, including active earth pressure, formation water pressure, and ground surcharge-induced lateral pressure. Notably, soil shear strength and mud relative density are two dominant factors controlling hole wall stability, and a positive correlation exists between these two parameters and stability. Specifically, a mud relative density range of 1.15–1.25 is recommended for practical construction. These findings offer valuable technical references for the design and construction of similar large-diameter bored pile projects in thick sand layers.
Ye, TaoWang, Ruyi
This specification covers a premium aircraft-quality, corrosion- and heat-resistant steel in the form of bars, wire, forgings, mechanical tubing, flash-welded rings, and stock for forging or flash-welded rings.
AMS F Corrosion and Heat Resistant Alloys Committee
This specification covers a low-alloy steel in the form of bars, forgings, mechanical tubing, and forging stock.
AMS E Carbon and Low Alloy Steels Committee
This specification covers a premium aircraft-quality, low-alloy steel in the form of bars, forgings, mechanical tubing, and forging stock.
AMS E Carbon and Low Alloy Steels Committee
This specification covers a premium aircraft-quality, low-alloy steel in the form of bars, forgings, mechanical tubing, and forging stock.
AMS E Carbon and Low Alloy Steels Committee
This specification covers a corrosion-resistant steel in the form of bars, wire, forgings, and forging stock.
AMS F Corrosion and Heat Resistant Alloys Committee
This specification covers a corrosion- and heat-resistant steel in the form of forgings, wire, bars, mechanical tubing, flash-welded rings, and stock of any size for forging or flash-welded rings.
AMS F Corrosion and Heat Resistant Alloys Committee
ACBG Rolling Element Bearing Committee
As a typical material for fragmentation warheads, the mechanical behavior and ballistic penetration performance of 10# steel are critical for assessing warhead lethality. To characterize the dynamic response of 10# steel, systematic experiments were conducted, including quasi-static tensile tests, split-Hopkinson tensile bar tests, and thermal softening measurements. A = 505.46 MPa, B = 292.84 MPa, n = 0.335, C = 0.0343, and m = 1.213 are the calibrated Johnson–Cook parameters. Bridgman-corrected notched tensile tests determined damage parameters D1 to D4: 0.065, 0.746, −0.646, and 0.031). A study of its constitutive behavior shows that the strength of 10# steel increases with stress triaxiality and strain rate, whereas increasing temperature enhances ductility and reduces strength. Finite element software was updated to include the calibrated parameters to develop a material model for ballistic impact simulation. When compared with the ballistic penetration test results obtained using a 14.5 mm projectile, the simulated residual velocities show less than 5% deviation from the measured values. 3D scanning reveals that fragment sizes in experimental data differ by under 10% from simulation predictions. This work enables precise numerical simulations for warhead fragmentation prediction and lightweight armor design.
Tian, YumoZhang, LonghuiAn, FengjiangFeng, Bo
Aircraft engine parts are extremely precise, and for deep, small-hole machining of the stainless steel 05Cr17Ni4Cu4Nb valve seat, the quality and sealing of the parts machined with current machining parameters are poor. This greatly affects production efficiency and quality. This article takes the optimization of the three elements of cutting as the starting point, uses the orthogonal experimental method to study which force most affects machining quality in the three directions of boring force, and selects the appropriate three elements of cutting to reduce cutting force. And analyzed the simulated chip shapes before and after optimization, and finally verified the optimization effect through the instrument equipment. A micro three- axis accelerometer was used to conduct machining experiments on deep small holes with cutting parameters before and after optimization. After optimization of cutting parameters, the tool's maximum axial deformation showed a reduction of about 51.60%, a reduction of approximately 58.75% was achieved in the maximum radial deformation, the maximum tangential deformation exhibited a decline of about 45.17%, and the peak overall deformation was reduced by approximately 50.66%. Compared with the pre-optimized state, using optimized cutting parameters to machine deep small holes resulted in a 72.31% reduction in the tool's axial acceleration, the radial acceleration by 63.36%, and the tangential acceleration by 71.68%, the tangential force by 65.29%, the axial force by 27.93%, and the radial force by 31.16%. Effectively reducing tool chatter and lowering chatter amplitude led to the disappearance of surface vibration patterns on the machined parts.
Liu, XinweiShi, GuangfengZhou, YuningGao, Jinglong
A certain component features an overall thin-walled structure with a wall thickness less than 1 mm, manufactured from high-strength martensitic precipitation-hardening steel. This part demands extremely stringent dimensional accuracy, with circumferential wall thickness variation not exceeding 0.006 mm, making it a typical high- precision thin-walled component. To ensure component performance and material utilization, the primary forming processes include spin forming, solution heat treatment, and multiple turning operations. During actual machining, martensitic precipitation-hardening steel exhibits significant microstructural stress relaxation and uneven cooling after solution heat treatment, leading to substantial part deformation. This makes it difficult to control subsequent machining dimensions within tolerance limits. Additionally, conventional clamping methods during multi-pass turning operations often cause uneven stress distribution on components during processing, frequently resulting in dimensional deviations that severely impact finished product yield rates. To address this challenge, this study systematically developed specialized tooling design and optimized turning processes tailored to the structural characteristics and deformation mechanisms of these thin-walled tube blanks. Simultaneously, a gap-free turning fixture with uniform expansion and clamping capabilities was developed. Combined with optimized machining parameters during the turning stage, this significantly improved stress distribution during processing, preventing further deformation caused by localized stress concentration. Test results indicate that after process optimization, the overall machining accuracy of this component improved by approximately 70% compared to the original process. Critical geometric tolerances showed significant enhancement, with roundness error consistently controlled within 0.30 mm and diameter dimensional consistency markedly improved. These measures not only successfully addressed deformation control challenges during heat treatment and machining of thin-walled parts but also provided a viable process solution and technical reference for precision manufacturing of similar high- difficulty, high-precision components.
Kou, YueZhao, Honglian
The core challenge of in-service welding repair of oil and gas pipelines is the risk control of burn-through. Current research primarily focuses on macroscopic phenomena, lacking a systematic multi-scale analysis of burn-through mechanisms and their dynamic evolution. Existing criteria are primarily based on qualitative experience, and widely accepted quantitative safety assessment standards have yet to be established. Furthermore, insufficient understanding of multi-scale damage failure mechanisms and weak theoretical foundations have become bottlenecks in this field. This study targets X65 pipeline steel and combines in-service welding experiments with in-situ scanning electron microscope tensile tests to elucidate the formation mechanism of burn-through from a multi- scale perspective. The results show that during in-service welding, the remaining wall thickness of the pipeline continuously decreases with the welding process, ultimately resulting in burn-through holes. On one hand, the welding arc drives the expansion of the hole; on the other hand, the internal pressure of the medium further enlarges the hole, leading to the expulsion of water and rapid pressure loss in the pipeline. Notably, the fusion zone behind the maximum melt depth is subject to high temperatures, which reduces strength and degrades plasticity, exhibiting significant plastic strain, making it a high-risk area for burn-through instability. Before instability occurs, this region shows evident grain coalescence, with plastic deformation primarily occurring through dislocation slip; when the difficulty of activating slip systems increases, twinning deformation may be induced, and large twin grains rarely develop cracks. Strain concentration and crack initiation are more likely to occur between grains with significant orientation differences.
Wang, BangyuQiao, YingJieLi, DongXu, ShiHang
This specification covers a corrosion- and heat-resistant steel in the form of seamless tubing.
AMS F Corrosion and Heat Resistant Alloys Committee
This specification covers an aircraft-quality, low-alloy steel in the form of sheet, strip, and plate.
AMS E Carbon and Low Alloy Steels Committee
This specification covers a premium aircraft-quality, low-alloy steel in the form of bars, forgings, mechanical tubing, and forging stock.
AMS E Carbon and Low Alloy Steels Committee
This SAE Recommended Practice describes chemical analysis, hardness, microstructure, and physical characteristic requirements for low carbon cast steel shot to be used for shot peening or blast cleaning operations.
Surface Enhancement Committee
This specification covers a corrosion-resistant steel in the form of sheet, strip, and plate.
AMS F Corrosion and Heat Resistant Alloys Committee
This specification covers a corrosion- and heat-resistant steel in the form of forgings and forging stock.
AMS F Corrosion and Heat Resistant Alloys Committee
This specification covers a corrosion-resistant steel in the form of investment castings.
AMS F Corrosion and Heat Resistant Alloys Committee
Fracture failure of girth welds in high-grade steel pipelines poses a critical threat to pipeline integrity. Leveraging enhanced digitalization in pipeline engineering, a statistical database has been developed to support reliability analysis based on actual operational data. This study utilizes real project data to analyze the failure probability and key influencing factors of girth welds containing crack defects, thereby providing theoretical support for safety design and risk management. To overcome the conservatism of traditional deterministic methods, a probabilistic reliability model was established, incorporating a modified PRCI-CRES ultimate tensile strain criterion. Addressing the inefficiency of standard Monte Carlo (MC) simulation in high-dimensional low-probability contexts, an efficient Hamiltonian Monte Carlo-Subset Simulation (HMC-SS) strategy was introduced. Results show that HMC-SS improves computational efficiency by 99.95% over MC, with only 0.90% relative error. Key findings include: crack depth has the strongest influence – variation from 0.92 mm to 3.68 mm, which increases failure probability by 103 times; the strength matching coefficient is dominant, and higher values reduce failure risk; strain demand exhibits a positive correlation with failure probability and couples with material properties. It is concluded that high- or equal-strength material matching should be emphasized in welding, and reliability-informed design should account for multi-parameter interactions to ensure global safety.
Yang, KaiWang, KaihongWang, BinShao, JiaYu, WeichaoZhang, Dong
Amid the rapid development of the new energy vehicle industry, the vehicle frame, as the core load-bearing component of the entire vehicle, plays a direct role in the vehicle’s safety, lightweight design, and power performance through its design and performance. Although research on new energy vehicle frames has matured, issues related to the lightweighting of drive shaft-associated structures and the balance between weight reduction and strength/stiffness still require in-depth exploration. This study focuses on the chassis of new energy vehicles, utilizing Q295 low-alloy high-strength steel. Based on the vehicle’s dimensions and mass parameters, a simplified 3D model was constructed using SolidWorks. Static analysis under bending and torsion conditions, along with a 6th-order modal analysis, was conducted using ANSYS software. Based on the analysis results, optimizations were implemented at both structural and material levels: structurally, the central crossbeam was widened, holes were opened on the crossbeam’s vertical plane to reduce weight, and the longitudinal beam welding process was optimized; materially, Q295 steel was retained in high-stress zones, while aluminum alloy replaced it in low-stress zones. The optimized frame achieved a 15% reduction in torsional stress, a 16% decrease in bending stress, a 2% reduction in torsional deformation, and a 3% decrease in bending deformation. Total mass decreased by 12.7 kg, with both strength and stiffness meeting design requirements. This approach synergistically enhances frame lightweighting and performance, providing technical support for optimizing the overall performance of new energy vehicles.
Guo, LihongWang, YiyouYang, Zihao
This specification covers a corrosion-resistant steel in the form of wire 0.007 to 0.625 inch (0.18 to 15.88 mm), inclusive, in nominal diameter, cold drawn to Condition C, and capable of being precipitation heat treated to Condition CH900.
AMS F Corrosion and Heat Resistant Alloys Committee
Steel structures subjected to complex loading conditions undergo various types of damage, including fatigue, crack propagation, plastic deformation, and corrosion. As time and loads accumulate, these damages may lead to structural failure. The investigation of the damage mechanisms and constitutive models for special equipment steel structures under complex loading has been a significant challenge in engineering. This study develops a constitutive model for steel structure damage under static and dynamic loads, as well as vibration disturbances, through a normalization approach. The proposed model is validated via simulation to assess its feasibility. The findings offer a theoretical foundation for the design, life prediction, and health monitoring of steel structures in special equipment, aiming to enhance their safety and reliability. This research provides critical insights into damage analysis, failure prediction, and the optimization of repair strategies for steel structures, with significant practical implications in engineering applications.
Wang, JunYu, ZhenHuang, Yong-qiangChen, Wei-bi
Corrosion-wear damage behavior affects the bearing life and reliability seriously in a corrosive environment. The accurate evaluation of the tribocorrosion behavior of 8Cr4Mo4V bearing steel samples is critical for the application and protection of bearings. The present work seeks to establish the relationship between laboratory salt spray accelerated experiments and the corrosion of 8Cr4Mo4V steel samples in real outdoor marine atmosphere exposure, and investigate the tribological behavior in the corrosion-wear process under artificial seawater. Results show that salt spray corrosion tests can well simulate the corrosion of 8Cr4Mo4V steels in marine atmospheric exposure. The tribocorrosion performance of 8Cr4Mo4V steels under artificial seawater conditions is affected by the temperature effect of the corrosive liquid and the working conditions. Increased normal load and reduced rotational speed can improve the anti-friction performance. This work offers the possibility and reference of precise control of corrosion-wear-coupled damage failures for bearings.
Zhao, ChaoYing, LixiaNie, ChongyangZhu, TianlinSun, Dong
This specification covers a corrosion- and heat-resistant steel in the form of wire.
AMS F Corrosion and Heat Resistant Alloys Committee
This specification covers an iron-nickel alloy in the form of strip 0.020 to 0.250 inch (0.51 to 6.35 mm), inclusive, in nominal thickness.
AMS F Corrosion and Heat Resistant Alloys Committee
This specification covers a corrosion-resistant steel in the form of bars, wire, forgings, extrusions, flash-welded rings, and stock for forging, extruding, or flash-welded rings.
AMS F Corrosion and Heat Resistant Alloys Committee
This specification covers a nitriding grade of premium aircraft-quality, low-alloy steel in the form of bars, forgings, mechanical tubing, and forging stock. AMS6496 and AMS6498 cover UNS K23280 with other quality levels.
AMS E Carbon and Low Alloy Steels Committee
This specification covers a corrosion- and heat-resistant steel in the form of welding wire.
AMS F Corrosion and Heat Resistant Alloys Committee
This specification covers a corrosion- and heat-resistant steel in the form of welding wire.
AMS F Corrosion and Heat Resistant Alloys Committee
A machine-learning strategy has generated a new class of ultra-high strength and ductility steel for 3D printing that costs less, resists rust, and requires only a fraction of the usual processing time.
Vacuum laser welding trials were carried out on 42CrMo steel, a material widely utilized in the defense sector. By employing a 30 kW fiber laser system, complete penetration welds were successfully produced on 20 mm thick 42CrMo steel plates. The resulting joints displayed satisfactory surface quality on both the top and bottom sides, with no evident defects such as cracks or porosity. A comprehensive analysis of the joint microstructure and mechanical properties was conducted. Findings reveal that the weld zone (WZ) is predominantly composed of lath martensite, accompanied by minor quantities of plate martensite, organized as columnar crystals. The joints demonstrated high tensile strength at ambient temperature, with fracture consistently occurring within the base metal (BM). Microhardness measurements indicated higher values within the weld relative to the base metal, and no pronounced softening was detected in the heat-affected zone (HAZ). Additionally, the joints exhibited commendable impact toughness, suggesting overall superior mechanical performance.
Shi, HaichengZhang, GuoyuLi, WuhongCao, DongxuLiu, Tianlei
Ultrasonic guided waves enable long-range, low-intrusion inspection of pipelines. This study examines how array topology and axial spacing influence the quality of defect echoes when the longitudinal axisymmetric mode L(0,2) is used. We build COMSOL finite-element models of a steel pipe and excite it with PZT-4 at 80 kHz; three practical layouts are compared: (i) odd–even receiving, (ii) 8-transmit/8-receive, and (iii) 16-transmit/8-receive, arranged as two axially separated groups. The spacing between the groups is chosen to suppress parasitic modes such as L(0,1) and to strengthen L(0,2). Results show that the two-group configuration sharpens the defect echo and reduces modal interference; increasing the number of transmitters further raises the defect-wave amplitude and improves the separation from end-reflection echoes. Among the schemes, 8×8 performs well for small-defect identification, while 16×8 yields the clearest boundaries and fastest defect indication. These findings clarify how sensor number and placement govern modal purity and sensitivity, and they offer practical guidance for designing guided-wave arrays that improve the reliability of long-range pipeline inspection. - Ultrasonic guided waves Pipeline non-destructive testing L(0,2) mode; Sensor array layout; Finite element simulation; Guided wave signal processing.
Liao, WeiLi, TengfeiZhang, WenhuiLin, QingmingGuo, Yanbing
To address the safety assessment challenges of T91 steel heating surface components in the context of coal-fired power plant transformation toward deep peak-shaving, this study systematically investigates the evolution laws of microstructure and mechanical properties of in-service T91 pipes from different positions in a power plant after peak-shaving operation. Material properties were evaluated in accordance with standards such as GB/T 5310-2017 through metallographic analysis, tensile testing, impact testing, and hardness measurement, while the mechanisms linking microstructure to property degradation were explored. Results show that oxidation and decarburization occur on the outer surface of T91 pipes at all positions, with differences in the thickness of oxide/decarburized layers between the fire-facing and back-fire surfaces; the oxide layer exhibits fracture characteristics. After service, the tensile strength, yield strength, elongation, and hardness of the material still meet national standards. The performance at the platen and final superheater inlet is superior to that at the final reheater inlet, consistent with differences in operating temperature and pressure. This study indicates that the T91 steel provided in this study is in the early stage of its service life, providing a theoretical basis for the safe operation of the unit.
Huang, LimingLi, ZutaoZhang, JieLiu, Yaoren
SiC-based power devices are favored for high-voltage and high-power applications due to their superior material properties. However, the demand for higher breakdown voltages and improved channel mobility presents significant challenges to the etching process, especially the micro-trenching effect. In this study, etching results from inductively coupled plasma (ICP) have been presents, which focused on using various SF6/O2/Ar gas ratios to eliminate micro-trenching effect. The profile analysis of micro-trench was taken by cross-sectional scanning electron microscopy (SEM). The results demonstrate that micro-trenches primarily originate from the coupling effect between ion multi-reflection from sidewalls and redeposition of etch byproducts. Based on this mechanism, we propose a quasi-Bosch process: a combined polymerization and etching step in oxygen-fluorine-rich plasma deposits polymer on exposed SiC and the mask, while removing it from the structure bottom via ion bombardment to enable etching and passivation; then alternates with a short fluorine-plasma step, which consumes sidewall polymer through ion incidence and prevents SiFxOy charge accumulation, cycle etching gradually deepens the structure without micro-trenches. Different gas ratios and etching time not only change the plasma energy distribution but also affect the temporal synchronization between etching and passivation steps. This approach reduces the special demands on ICP equipment capabilities while achieving superior trench profiles. The optimal etching conditions produced a micro-trench-free SiC structure with a vertical sidewall angle and a surface roughness of less than 1 nm. This methodology and resulting structures significantly advance the manufacturability of high-performance SiC power devices, enabling next-generation applications in electric vehicles and grid infrastructure where device yield and reliability are paramount.
Zhao, YingfanDong, ShuangSun, XiaoxuChang, XiangpengLiang, YiweiTong, Weiping
Lunar dust consists of extremely fine particles and exhibits electrostatic charging properties and electrostatic adhesion. These characteristics cause lunar dust to be highly susceptible to mobilization during lander touchdowns, rover traversals, and human activities, forming widely distributed dust clouds. Lunar dust contamination not only abrades spacecraft and equipment to impair their performance but also poses a threat to astronauts’ safety. To verify the impact of the lunar dust environment on exploration equipment components, a simulation mechanism adaptable to the thermal vacuum test environment was designed. This mechanism is integrated into the lunar environment simulation system and uses a vacuum stepper motor to drive a ratchet mechanism, enabling precise vibrational injection of simulated lunar dust. It mainly consists of a pretreatment mechanism, a particle sedimentation mechanism, a shielding mechanism, and an ultraviolet (UV) irradiation system. Considering the vacuum operating environment, alternating high and low temperature conditions, as well as the strict requirements for the mechanism’s compact size and high reliability, this paper analyzes in detail a series of problems encountered during the development of the mechanism and their corresponding solutions. Stainless steel and polytetrafluoroethylene (PTFE) were selected as the main materials for the mechanism. Meanwhile, active temperature control measures were adopted to actively regulate the temperature of components such as the motor. Ultimately, the mechanism can withstand alternating high and low temperatures ranging from -150°C to 150°C and a vacuum environment of 5 × 10^–6 Pa. Under this environment, the mechanism can achieve vibration frequency adjustment within the range of 1-5 Hz, and realize the sedimentation of simulated lunar dust particles with a particle size of less than 200 μm over an area of 150 mm × 150 mm. After sedimentation, the simulated lunar dust particles can be charged through the photoelectric effect.
Xu, MenglongLv, ShizengLi, GuohuaGong, Jie
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