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This paper proposes a piezoelectric energy harvester that concentrates force on the piezoelectric element by parallel springs. When vibrating, the force exerted by the mass is released at three equal points on the surface of the brass substrate through three parallel springs. This concentrated release of energy through the spring amplification effect facilitates large deformation of the piezoelectric ceramic sheet, resulting in a higher charge output. The results show that under the combined action of a 14 g annular hollow mass and a 0.3 mm wire diameter stainless steel spring, the energy harvester based on the lead zirconate titanate ceramic exhibited an outstanding output power of 1.0–32.1 mW at a low resonance frequency with acceleration amplitudes of 0.5–3 g (1 g = 9.8 m/s2). More importantly, to match the vibration frequency of the actual environment, this paper optimized the structure of the harvester and proposed that the harvester can be designed by selecting the weight of the mass block, the parameters and number of springs, and the shape of the brass substrate. The energy harvester designed in this study is expected to capture energy from low-frequency natural environments and exhibit outstanding output performance, which can provide guidelines for future efforts in this direction. [ABSTRACT FROM AUTHOR]

Active thermography using pulsed heating is a fast and reliable method for detecting flaws in composite and metallic materials. This paper analyzes the temperature decay that occurs immediately after flash heating the front surface of stainless steel specimens as a function of time, based on a novel application of the equivalent circuit approach (ECA). The temperature decay from the front surface is equated to the discharge of a capacitor. The ECA is based on the charging (temperature rise due to flash heating) of a capacitor, followed by its discharge (temperature decay) through a series of resistors (which depends on the conductivity of the material) and capacitance (which depends on the thermal capacitance of the layers) through which the heat is dissipated. The proposed approach analyzes the sequences of temperature data obtained at each pixel location during cooling from a step wedge and a specimen with multiple flat-bottom holes. Time constant maps derived from the analysis are used to ascertain the thickness of the step wedge, detect the flaws, and evaluate the remnant thickness of the flaws. A correlation has been established between the thickness and the time constants. The above approach has been used to estimate the diameter of the flat-bottom holes. [ABSTRACT FROM AUTHOR]

Additive manufacturing has the potential to repair damaged parts, but the performance of additive materials under high strain rate loading is still uncertain—especially with the added complexity of an interface with an existing wrought material. In this work, 304L stainless steel samples were intentionally damaged and then repaired with wire-fed laser additive manufacturing. The samples were subjected to shock loading to generate incipient spall. Velocimetry and post-mortem metallography results show that when the additive repair process parameters are optimized to reduce porosity and match the equation of state of the original material, the influence of the repair region on the shock propagation is negligible. The free-surface velocity profile and internal damage morphology of the repaired sample are shown to be practically identical to the pristine material. [ABSTRACT FROM AUTHOR]

Properties of fragmentation from an explosively driven 316L stainless steel spherical shell section fabricated by a laser powder bed additive manufacturing process with minimal surface finishing are investigated. This shell is driven by an insensitive high explosive, resulting in high strain rate deformation (>8 × 103 s−1) and failure of the stainless steel. Photonic Doppler velocimetry measures the expansion rate; dynamic radiography and high-speed imaging capture the fracture behavior of the stainless steel. The fracture response of the additively manufactured stainless steel shell is compared to published experimental results on additively manufactured 316L stainless steel and conventionally manufactured wrought 316L and 304 stainless steel shell fragmentation. Despite preferred crack orientation, suggesting the influence of surface grooves on fracture time, fragment size is identical to that measured in a similar experiment on wrought 304 stainless steel. Further analysis indicates that the 316L additively manufactured stainless steel shell exhibits comparable spall strength and fragmentation toughness to conventionally manufactured stainless steel yet lower failure strain due to surface stress concentrations. [ABSTRACT FROM AUTHOR]

We present a systematic study of Hugoniot properties of porous 316L stainless steel using both a simple interpolation scheme and direct shock simulations in order to probe pore collapse kinetics as well as final thermodynamic states. Both methods indicate that equilibrated Hugoniot properties depend on pore density only and not on the pore distribution or size. We then create a simple porous equation of state model that is shown to be accurate for a range of validation data. This allows us to extend our simulations to make direct comparison to experimental data that have generally significantly larger system sizes and durations. In addition, our direct shock simulations indicate that the relaxation time after hotspot formation is system size dependent and can reach nanosecond timescales for the largest pores investigated in our study, thereby possibly having a measurable effect on fast dynamic loading experiments [ABSTRACT FROM AUTHOR]

This work presents first experiments toward the development of continuously renewable (extrudable) pebble-based carbon rods for use as plasma-facing components in extreme steady-state plasma flux environments. The primary envisioned application of this work is a first wall that can survive long-term in future magnetic fusion power reactors while also improving recovery of the reactor fuel (tritium and deuterium atoms). Bench tests applying extreme steady-state front-surface heat loads of up to 50 MW/m2 are presented. Continuous pebble rod front-surface recession and intact pebble recovery are successfully demonstrated, at a rate of order 0.2 cm/s. Numerical simulations of the pebble rod front-surface recession are able to match observations reasonably well, indicating that the recession mechanism can be understood as occurring due to pebble thermal expansion and resulting shock and cracking of the inter-pebble binder. Tests of the pebble rod extrusion demonstrate that friction between the rods and the stainless steel extrusion channel is tolerably low (<50 N for the expected channel length) over a wide range of temperatures. Front-surface outgassing rates below 1000 Torr L/s/m2 are achieved, believed to be sufficiently low for use in magnetic fusion reactors. Initial parametric scans over pebble rod size and binder fraction to vary front-surface recession rates are presented. [ABSTRACT FROM AUTHOR]

This paper reports on spall failure and damage modes in Laser Powder Bed Fusion fabricated Stainless Steel 316L (SS316L) with intentional levels of low-volume (1–5 vol. %) porosity and pore sizes of 200, 350, and 500 μm. The fabricated specimens were subjected to uniaxial-strain plate-impact loading at ∼4.5 GPa, to initiate incipient spall failure. Analysis of velocimetry profiles measured using multi-probe photon-Doppler velocimetry coupled with post-mortem analysis of soft-recovered samples reveals local suppression of spall failure (termed as spall-dominated) as a function of porosity, as the failure mechanism transitions from spall-centered tensile stress dominated to a pore-centered microstructure-dominated damage mode involving void/crack nucleation and growth at pre-existing pores. The critical porosity level where the suppression of spall failure is first observed, as well as the spall location, is dependent on both the volume fraction and the size of the initially fabricated pores. In samples of 500 μm pore size, the suppression of spall failure is observed with as little as 1 vol. % porosity, while samples with smaller pores (200 μm) still experience spall-centered tensile stress dominated failure with higher levels (5 vol. %) of porosity. In the case of pore-centered microstructure-dominated failure, spall damage can occur but the spall plane is shifted toward the rear free surface, or more generally in areas further away from the region with pores. Highly heterogeneous deformation twinning, shear banding, grain rotation, and cracking are observed in the vicinity of pre-existing pores and expected spall failure sites. [ABSTRACT FROM AUTHOR]

Background: Basicervical femoral neck fracture is a rare proximal femur fracture with a high implant failure rate. Biomechanical comparisons between cephalomedullary nails (CMNs) and dynamic hip screws (DHSs) under torsion loading are lacking. This study compared the biomechanical performance of three fixations for basicervical femoral neck fractures under torsion load during early ambulation. Methods: The biomechanical study models used three fixations: a DHS, a DHS with an anti-rotation screw, and a short CMN. Finite element analysis was used to simulate hip rotation with muscle forces related to leg swing applied to the femur. The equivalent von Mises stress (EQV) on fixation, fragment displacement, and strain energy density at the proximal cancellous bone were monitored for fixation stability. Results: The EQV of the short CMN construct (304.63 MPa) was comparable to that of the titanium DHS construct (293.39 MPa) and greater than that of the titanium DHS with an anti-rotation screw construct (200.94 MPa). The proximal fragment displacement in the short CMN construct was approximately 0.13 mm, the greatest among the constructs. The risk of screw cutout for the lag screw in short CMNs was 3.1–5.8 times greater than that for DHSs and DHSs with anti-rotation screw constructs. Conclusions: Titanium DHS combined with an anti-rotation screw provided lower fragment displacement, stress, and strain energy density in the femoral head than the other fixations under torsion load. Basicervical femoral neck fracture treated with CMNs may increase the risk of lag screw cutout. [ABSTRACT FROM AUTHOR]

Newly synthesized gemini quaternary ammonium salts (QAS) with different counterions (bromide, hydrogen chloride, methylcarbonate, acetate, lactate), chain lengths (C12, C14, C16) and methylene linker (3xCH2) were tested. Dihydrochlorides and dibromides with 12 carbon atoms in hydrophobic chains were characterized by the highest biological activity against planktonic forms of yeast and yeast-like fungi. The tested gemini surfactants also inhibited the production of filaments by C. albicans. Moreover, they reduced the adhesion of C. albicans cells to the surfaces of stainless steel, silicone and glass, and slightly to polystyrene. In particular, the gemini compounds with 16-carbon alkyl chains were most effective against biofilms. It was also found that the tested surfactants were not cytotoxic to yeast cells. Moreover, dimethylcarbonate (2xC12MeCO3G3) did not cause hemolysis of sheep erythrocytes. Dihydrochlorides, dilactate and diacetate showed no mutagenic potential. [ABSTRACT FROM AUTHOR]

To improve the corrosion resistance and interfacial contact resistance (ICR) 316L stainless steel bipolar plates used in proton exchange membrane fuel cells (PEMFCs), a series of three-layer amorphous carbon films were prepared by magnetron sputtering. The corrosion resistance and ICR of 316 L stainless steels are greatly improved by the Cr, N doped amorphous carbon and multilayer film structure. Ti and CrN were basement layer and transition layer, and amorphous carbon doping with Cr and N was the top layer. Nitrogen atoms, as the variable atoms, were added into the top layer, focusing on the relation between the N content and the film properties. First principles calculations were used to analyze the bond structure by Cr, N doping into amorphous carbon structure and to determine the reasons for the structural changes in the coating after doping the elements. The results revealed that the films are about 1.05 μm thick and without apparent defects. With increasing nitrogen flow rate, Cr–N bonds and C–N bonds appeared in the coating while promoting the graphitization of amorphous carbon. Compared with that of Cr-doped amorphous carbon coated steel, the corrosion current density of Cr, N co-doped amorphous carbon decreased to 8.1 × 10−9 A/cm2 in the +0.6 V (vs. SCE) potentiostatic polarization test, and as the ICR decreased to 1.3 mΩ cm2, the film exhibited outstanding corrosion resistance and conductivity properties. The Cr, N co-doped amorphous carbon/CrN/Ti composite film formed on 316L stainless steel might be appropriate used in PEMFCs. • Cr, N co-doped amorphous carbon - CrN–Ti composite coatings are prepared. • Cr–N bonds and C–N bonds appear in the coating and influence the property. • Nitrogen addition improves coatings corrosion resistance and ICR. [ABSTRACT FROM AUTHOR]

Precipitation hardening (PH) stainless steels, such as 15-5PH, have a high strength combined with excellent corrosion resistance. These properties make them valuable in critical industries such as defence, construction, aerospace, energy and maritime. Recent advancements in additive manufacturing (AM) technology enable the rapid and cost-effective production of components. In the case of 15-5PH components manufactured using wire arc additive manufacturing (WAAM), the as-deposited mechanical properties are not suitable at present for industrial applications. This paper explores the mechanical properties of this process and alloy combination without post weld heat treatment with the aim of eventual adoption in this condition by industry. The impact of weld heat input on the microstructure and mechanical properties of stainless steel 15-5PH produced using WAAM was investigated. The microstructure was examined using hardness testing in addition to optical and electron microscopy. Furthermore, mechanical properties were measured with tensile and impact testing. Investigations were conducted on material produced using weld heat inputs of 0.223 kJ/mm and 0.565 kJ/mm. These results indicate that reducing the weld heat input leads to a minor decrease in strength but an 80% increase in impact toughness. This reduction in weld heat input is correlated with a 50% reduction in volume fraction of δ-ferrite while also noting a 55% increase in carbide precipitates. In addition, the fracture surfaces were predominantly cleavage or quasi-cleavage in morphology. [ABSTRACT FROM AUTHOR]

This paper presents a thorough manufacturability study of 2507 super duplex stainless steel (SDSS) produced by the Laser Powder-Directed Energy Deposition (LP-DED) process. First, experimental observations on single-track surface morphology and geometrical characteristics are described. Then, dimensional and porosity analyses of thin walls and bulk samples are presented and discussed in order to identify the optimal process parameter combinations, from a process point of view, for further characterizations to determine the general properties of LP-DED-printed samples. Finally, the results obtained on wrought steel of the same grade are compared to those of the printed material in terms of microstructure, texture, and ferrite/austenite ratio. A set of meticulously chosen process parameters with regard to the process and the machine (nozzle size, maximum power deliverable) gives the optimal results for the as-built LP-DED material in terms of porosity and microstructure quality but with smaller grains (irrespective of the phase studied) and a higher proportion of ferrite (about 75%). [ABSTRACT FROM AUTHOR]

This study has been conducted on the machining of AISI 304 L stainless steels, which are difficult to machine, have chip-breaking problems, and therefore cause premature wear. A full factorial experiment was designed, and the experiments were conducted at five different inserts, five different cutting speeds, two different feeds, and three different cutting depths. As a result of the experiments carried out, the flank wear and surface roughness values were measured. Utilising Taguchi, Response Surface Methodology (RSM), and Artificial Neural Networks (ANN), interpolation estimates were obtained for flank wear and surface roughness, followed by optimisation investigations. The method with the least error was selected by examining the estimation results. Different methods confirm each other, and simultaneously, the chosen method strengthens the estimation. Confirmation experiments were performed for the parameters giving the optimum value. The optimal outcomes in the range of cutting tips and parameters were obtained with the insert with Al2O3+TiCN coating at a cutting speed of 170 m/min, a feed of 0.13 mm/rev, and a depth of cut of 1.1 mm. It has been seen that the validation experiments agree with the actual and estimated values. [ABSTRACT FROM AUTHOR]

Heat-assisted forming is gaining increasing attention for its potential in improving the formability and quality of metallic bipolar plate (BPP) of proton exchange membrane fuel cell (PEMFC). However, the effects of heat-assisted forming and the subsequent coating process on corrosion resistance and electrical conductivity of stainless steel BPP still remain unclear. This work proposes a way to improve simultaneously the corrosion resistance and electrical conductivity of heat-assisted forming stainless steel BPP by depositing a Cr–C coating directly on its surface without removing the oxide layer using the magnetron sputtering method. Potentiodynamic tests indicate that self-corrosion current density and corrosion current density at 1.0 V (vs. Ag/AgCl) of the Cr–C coated heat-assisted forming SS316L BPP prepared under 900 °C for 10 min are 0.021–0.040 μA cm−2 and 77.54 μA cm−2, respectively, both of which are smaller than those of coated SS316L BPP formed under room temperature. In addition, the contact resistance is close to that of the gold-plated copper plate under the same pressure. The corrosion resistant intermediate oxide layer and conductive network formed between Cr–C coating and metal substrate through defects of oxide layer may be the main reason for improvement of its corrosion resistance and electrical conductivity, respectively. [Display omitted] • A Cr–C coated heat-assisted forming bipolar plate with high performance is proposed. • Self-current densities of 0.022–0.056 μA cm−2 in fuel cell environment is obtained. • The retained intermediate oxide can contribute to a better corrosion resistance. • A lower electrical contact resistance approaching the gold coated copper is achieved. • The conductive network formed is beneficial for electrical conductivity improvement. [ABSTRACT FROM AUTHOR]

Improving the properties of metallic bipolar plates is very crucial for high performance of proton exchange membrane fuel cells (PEMFCs). Cr–C films are prepared on the stainless steel 316L substrate by RF multi-point magnetron co-sputtering of Cr sheets and graphite target for the first time. Effect of the number of Cr sheets on the morphology, composition, corrosion resistance, conductivity, and hydrophobicity of Cr–C films are investigated systematically. With the increase of the number of Cr sheets, the ratio of sp2/sp3 hybrid in the Cr–C films is decreased, and the films become more compact and smoother. When the number of Cr sheets is 8, the ratio of sp2/sp3 hybrid is 5.01, and the Cr–C film shows the best comprehensive performance. The corrosion current densities of anode and cathode are 0.31 μA cm−2 and -0.087 μA cm−2 at constant potential, respectively, and 0.229 μA cm−2 and -0.276 μA cm−2 at galvanic potential, respectively. The corrosion resistance property of the Cr–C film is superior to DOE standards. Compared with uncoated 316L stainless steels, the properties of corrosion resistance, conductivity, and hydrophobicity of the ones coated with the Cr–C films have been improved significantly. This work opens up a new way for the preparation of metal bipolar plate films. • A method for RF multi-point magnetron co-sputtering is proposed. • The effect of the number of sheet on the properties of CrC films is studied. • CrC films with excellent corrosion resistance and hydrophobicity are prepared. • The films deposited with the number of 8 Cr sheets has the best performance. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this paper is to investigate the effect of laser peening (LP) on mechanical and wear properties of 304 stainless steel sheet. Design/methodology/approach: Three-dimensional morphology, micro-hardness and micro-structure of shocked samples were tested. The wear amount, wear track morphology and wear mechanism were also characterized under dry sliding wear using Al2O3 ceramics ball. Findings: The LP treatment generates deformation twins that contribute to the grain refinement and hardness increase. The wear test displays that the wear mechanism of samples is mainly abrasive wear and oxidation wear at 10 N load. While at 30 N, the delamination and adhesion areas of treated sample are reduced visibly compared to untreated ones. Originality/value: This study specifically investigates the mechanical and wear properties of 304 stainless steel after the direct action of LP on its surface, which shows an effective improvement on the wear resistance. For example, the wear loss of processed sample is reduced by 19% at 30 N, the friction coefficient decreases from 0.4714 to 0.4308 and the groove depth is reduced from 78.1 to 74.4 µm under same condition. Peer review: The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-01-2024-0007/ [ABSTRACT FROM AUTHOR]

A hybrid mold is developed, with its structure including some components made of polymer, as a variant to a classical structure. This hybrid mold is destinated to manufacturing, by cold plastic deformation, of stainless steel thin parts, in particular of certain 0.1 mm thickness stainless steel bipolar plates (BPPs) from proton exchange membrane fuel cell stacks. The mold conceptual and designed main data are revealed. Numerical simulation and analysis by a structural FEA method is applied. A general evaluation is unrolled, with the results referring to the technical – economic use of the developed hybrid mold. [ABSTRACT FROM AUTHOR]

The deposition process during emulsion polymerization can be classified as both particulate and reaction fouling, but a deeper understanding of the deposition mechanism, especially in combination with the polymerization process, is lacking. Here, a more in‐depth understanding of the deposition mechanism is sought by investigating the fouling formation of a Vinyl acetate and Versa 10 copolymer on a heated stainless steel surface during emulsion polymerization. Its deposition behavior is also compared with the behavior of an already reacted polymer. All possible influencing factors are investigated separately, and the fouling is quantified by the mass based fouling resistance and the fouling layer composition. The fouling rates of both experimental approaches (ongoing reaction versus already reacted polymer) are used to determine the fraction of reaction fouling along the reaction pathway. The solids content and the driving temperature difference are identified as the main factors influencing fouling formation. The deposited material is composed of latex particles and emulsifier with particle size and number depending on the respective equilibrium composition of the fluid phase. The reaction fouling rate is correlated with the proportion of free initiator radicals and the amount of dissolved monomer in the aqueous phase. [ABSTRACT FROM AUTHOR]

Buckling behaviour of axially and circumferentially loaded cylindrical shells made of high‐strength steels In the past, shell structures have largely been made of mild steels or austenitic stainless steels. However, high‐strength duplex stainless steels acc. to DIN EN 10088‐4, ‐5 are increasingly being used, e. g. in biogas fermenters. The use of high‐strength steels and duplex stainless steels not only reduces steel consumption and production costs, but also assembly costs, and thus significantly increases the competitiveness of tanks and silos in steel construction compared to containers made of other construction materials, e. g. concrete. One prerequisite, however, is that the problem of stability failure in the form of shell buckling can be eliminated. The European design standards for shell structures EN 1993‐1‐6, ‐4‐1, ‐4‐2 are developed for mild steels and do not take into account strength verification formats for ring‐stiffened and axially stiffened circular cylindrical shells for high‐strength structural steels and stainless steels with a nonlinear material behaviour below the 0.2 % yield strength. For this reason, within the framework of the IGF research project no. 21719N "Load‐bearing behaviour of meridionally and ring stiffened tanks and silos made of high strength (duplex) steels and low‐temperature steels for pressure vessels", systematic investigations are carried out on (un‐)stiffened circular cylindrical shells at the Institute of Metal and Lightweight Structures at the University of Duisburg‐Essen and the Testing Institute for Steel, Wood and Stone at the Karlsruhe Institute of Technology. The first results of this research project are presented here. [ABSTRACT FROM AUTHOR]

Current research studies devoted to cutting forces in drilling are oriented toward predictive model development, however, in the case of mechanistic models, the material effect on the drilling process itself is mostly not considered. This research study aims to experimentally analyze how the machined material affects the feed force (Ff) during drilling, alongside developing predictive mathematical–statistical models to understand the main effects and interactions of the considered technological and tool factors on Ff. By conducting experiments involving six factors (feed, cutting speed, drill diameter, point angle, lip relief angle, and helix angle) at five levels, the drilling process of stainless steel AISI1045 and case-hardened steel 16MnCr5 is executed to validate the numerical accuracy of the established prediction models (AdjR = 99.600% for C45 and AdjR = 97.912% for 16MnCr5). The statistical evaluation (ANOVA, RSM, and Lack of Fit) of the data proves that the drilled material affects the Ff value at the level of 17.600% (p < 0.000). The effect of feed represents 44.867% in C45 and 34.087% in 16MnCr5; the cutting speed is significant when machining C45 steel only (9.109%). When machining 16MnCr5 compared to C45 steel, the influence of the point angle (lip relief angle) is lower by 49.198% (by 22.509%). The effect of the helix angle is 163.060% higher when machining 16MnCr5. [ABSTRACT FROM AUTHOR]

Aluminum, traditionally the primary material for battery casings, is increasingly being replaced by UNS S 30400 for enhanced safety. UNS S 30400 offers superior strength and corrosion resistance compared to aluminum; however, it undergoes a phase transformation owing to stress during processing and a lower high-temperature strength. Duplex stainless steel UNS S 32750, consisting of both austenite and ferrite phases, exhibits excellent strength and corrosion resistance. However, it also precipitates secondary phases at high temperatures, which are known to form through the segregation of Cr and Mo. Various studies have investigated the corrosion resistance of UNS S 32750; however, discrepancies exist regarding the formation and thickness of the passivation layer. This study analyzed the oxygen layer on the surface of UNS S 32750 after secondary-phase precipitation. The microstructure, volume fraction, chemical composition, and depth of O after the precipitation of the secondary phases in UNS S 32750 was examined using FE-SEM, EDS, EPMA and XRD, and the surface chemical composition and passivation layer thickness were analyzed using electron probe microanalysis and glow-discharge spectroscopy. This study demonstrated the segregation of alloy elements and a reduction in the passivation-layer thickness after precipitation from 25 μm to 20 μm. The findings of the analysis aid in elucidating the impact of secondary-phase precipitation on the passivation layer. [ABSTRACT FROM AUTHOR]

Grain boundary (GB) precipitation-induced cracking is a significant issue for S31254 super austenitic stainless steel during hot working. Investigating the deformation behavior based on precipitate morphology and distribution is essential. In this study, continuous smaller and intermittent larger precipitates were obtained through heat treatments at 950 °C and 1050 °C. The microstructure evolution and mechanical properties influenced by precipitates were experimentally investigated using an in situ tensile stage inside a scanning electron microscope (SEM) combined with electron backscatter diffraction (EBSD). The results showed that continuous precipitates at 950 °C had a stronger pinning effect on the GB, making grain rotation difficult and promoting slip deformation in the plastic interval. Continuous precipitates caused severe stress concentration near GB and reduced coordinated deformation ability. Additionally, the crack propagation path changed from transcrystalline to intercrystalline. Furthermore, internal precipitates were a crucial factor affecting the initial crack nucleation position. Interconnected precipitates led to an intergranular fracture tendency and severe deterioration of the material's plasticity, as observed in fracture morphology. [ABSTRACT FROM AUTHOR]

The International Maritime Organization (IMO) is currently rolling out more restrictive regulations in order to achieve net-zero GHG emissions by 2050. In response, the shipping industry is planning to pivot to green energy sources such as hydrogen fuel. However, since hydrogen has an extremely low boiling point (−253 °C), materials for storing liquid hydrogen must be highly resistant to low-temperature brittleness and hydrogen embrittlement. A 316L stainless steel is a typical material that meets these requirements, and various welds have been studied. In this study, 3 pass butt welding was performed by applying the FCAW (flux cored arc welding) process to 10 mm thick ASTM-A240M-316L stainless steel, with the size of the fusion zone and HAZ investigated by mechanical testing and heat transfer FE analysis according to process variables, such as heat input, welding speed, and the number of passes. In all cases, the yield and tensile strengths were about 10% and 3% higher than the base metal, respectively. Furthermore, heat transfer FE analysis showed an average error rate of 1.3% for penetration and 10.5% for width and confirmed the size of the HAZ, which experienced temperatures between 500 °C and 800 °C. [ABSTRACT FROM AUTHOR]

Adhesive bonding has proven to be a reliable method of joining materials, and the development of new adhesives has made it possible to use bonding in a variety of applications. This article addresses the challenges of bonding metals such as the aluminum alloy EN AW-5754 and the stainless steel X5CrNi18-10. In this study, the effects of laser cleaning and texturing on the surface properties and strength of two bonded joints were investigated and compared with mechanical preparation (hand sanding with Scotch-Brite and P180 sandpaper). The bonded joints were tested with three different epoxy adhesives. During the tests, the adhesion properties of the bonded surface were determined by measuring the contact angle and assessing the wettability, the surface roughness parameters for the different surface preparations, and the mechanical properties (tensile lap-shear strength). Based on the strength test results, it was found that bonded joints made of stainless steel had 16% to 40% higher strength than aluminum alloys when using the same adhesive and surface preparation. Laser cleaning resulted in maximum shear strength of the aluminum alloy bond, while the most suitable surface preparation for both materials was preparation with P180 sandpaper for all adhesives. [ABSTRACT FROM AUTHOR]

AbstractThe stainless steel flat plate solar collector is a new type of collector that has a longer lifespan in high-temperature and high-humidity environments. When using stainless steel as the base material of the collector, the microchannel structure is typically employed to increase the heat transfer area and compensate for the lack of heat transfer coefficient of stainless steel. However, the shape of the channel section in microchannel structures affects the flow resistance of the heat transfer medium. This article presented the equation for the optimal feature size of the channel, obtained through fluid theory analysis of the stainless steel flat plate collector. The study analyzed the impact of different section parameters on the flow distribution and pressure drop characteristics of the medium in the channel through numerical simulation. The results showed that for a certain inlet flow rate, the cross-sectional geometry of the microchannel heat-absorbing plate determined the parameters such as the type of core cross-section, the degree of wall urgency, and the geometrical length of the microchannel, which in turn affected the distribution of the fluid in the flow channel and the energy loss. The optimal thermal performance of the stainless steel collector was observed when the width of the micro-channel was 8.7 mm and the corrugation height of the tube group was 3.00 mm. [ABSTRACT FROM AUTHOR]

This research has developed a fabricating process of thin‐strain sensor by utilizing wafer‐level‐packaging (WLP) techniques. The thickness of sensor makes thinner, its performance is able to highly increase. However, the thinner sensor was fragile, and so it was difficult to handle in post processes. Thus, a thin sensor with lid by utilizing WLP techniques, which is tough to break even when handled, is proposed in this research. More than 250‐µm‐deep grooves were fabricated around the lid by deep reactive ion etching. After the lid substrate was bonded on the sensor substrate with a resin, the sensor and lid substrates were respectively polished to 50 and 200 µm thickness. The lids were released along the grooves, and the 50‐µm‐thick strain sensors were able to be fabricated by utilizing WLP techniques. This sensor was used as a diaphragm to measure pressure. The sensors were assembled on a stainless steel housing without breakage. The performance of the developed sensor was almost showed with a conventional pressure sensor. [ABSTRACT FROM AUTHOR]

316L austenitic stainless steel (ASS) with a heterogeneous structure exhibits favorable mechanical properties at room temperature, promising excellent application potential. However, the thermal stability of 316L ASS with heterogeneous lamella structure (HLS) has not been adequately addressed yet. Herein, an HLS of 316L ASS is fabricated through 78% cold rolling followed by annealing at 750 °C for 13 min. The detailed investigation focuses on the influence of microstructure evolution on the mechanical properties and corrosion resistance of the alloy after aging at temperatures ranging from 350 to 550 °C for 100 h. The results show that a notable quantity of residual martensite persists even after annealing at high temperatures for a brief duration. The dislocation density of the test steel is reduced after long‐term aging treatment, and the residual martensite is further reversed into austenite during aging. In addition, the aging treatment also promotes further growth of nanocrystalline/ultrafine‐grained, which weakens the heterogeneous characteristics of HLS 316L ASS, resulting in a slight decrease in mechanical properties. However, the decrease in defect density and the enhancement of recrystallization degree are beneficial for eliminating most of the corrosion‐sensitive areas in the cold‐deformed structure, thereby improving the corrosion resistance. [ABSTRACT FROM AUTHOR]

An austenitic stainless steel 316L deposition specimen is fabricated by cold metal transfer‐based swing arc additive manufacturing (CMT‐SAAM), and its formation, microstructure, and tensile properties are investigated. The results showed that the 316L deposited samples exhibited a multi‐layer structure with a small aspect ratio, and the surface forming accuracy is improved with the increase in the swing amplitude. The remelted zone near the interface is dominated by long grains perpendicular to the fusion line, whereas the deposited zone is dominated by columnar dendrites and shows an <100> orientation. Along the building and transverse direction of the swing deposits, the microhardness distribution is uniform. Compared with rollings and forgings, 316L deposited by using the CMT‐SAAM method has both a higher strength and toughness. The average ultimate tensile strength is 573 MPa, and the elongation at break is 52.6%. The high strength and toughness of 316L specimens are attributed to the fine microstructure, high‐density dislocations, and low‐angle grain boundaries (LAGBs) generated during the CMT‐SAAM process. [ABSTRACT FROM AUTHOR]

The effect of spheroidizing annealing on carbide characteristic parameters, mechanical properties and wear resistance of the quenching and tempering (Q&T) high carbon martensitic stainless steel is investigated. The microstructure of the steel is characterized and analyzed through various techniques, including scanning electron microscope (SEM), X‐ray diffraction (XRD), electron backscattering diffraction (EBSD), and transmission electron microscope (TEM). Results show that the microstructure of the annealing steel is mainly composed of ferrite and M23C6 carbide. With the rise of austenitizing temperature, the average diameter of carbide of the annealed steel increases. The average diameter of carbides in the Q&T steel changes in the same way as that observed in the annealed steel. The steel has the lowest annealing hardness, highest Q&T toughness, and wear resistance at an annealed soaking temperature of 860 °C. The influence factor of the toughness and wear resistance can be identified that small‐sized carbides and low angle grain boundaries exhibit strong interface adhesive strength. This reduces the probability of cracking in the particle or at the interface. [ABSTRACT FROM AUTHOR]

The effects of current collectors on the battery performance have significant role, especially in aqueous electrolyte Al-ion batteries, as corrosion effects lead to rapid capacity degradation over cycles. To overcome this problem, we present a study investigating the selection of suitable current collectors and their impact on battery performance. Four different current collectors are selected for this. Stainless steel (SS), nickel foil (Ni), titanium foil (Ti) and graphite plate (GP). It has been proven by corrosion tests, cyclic voltammetry and charge-discharge studies that GP is the best current collector by minimizing the corrosion effect and H2 evolution reaction (HER). The anatase phase TiO2 used with GP current collector provides a 249 mAh g−1 initial discharge capacity at a current density of 3 A g−1, while inferior or no electrochemical activity is observed with Ti, SS, Ni current collectors. The observations here provide insights into the selection of corrosion-resistant current collectors to achieve stable battery performance in the field of aqueous electrolyte Al-ion batteries. [ABSTRACT FROM AUTHOR]

The laser-based thermomechanical joining process was adopted to produce hybrid components made of AISI 304 stainless steel and semi-transparent thermoplastic materials, i.e. polypropylene and polyamide. The process parameters, i.e. laser power, laser-polymer interaction time, and metal surface texture, were optimized using the full factorial experimental approach, and the joints' quality and performance were examined to determine the best operational parameters' combination. Shear tests were carried out to evaluate the resistance of the joints, while morphological and fracture surface analyses were performed to have a better understanding of the phenomena that emerged during the joining process. The findings demonstrated that the shear force and the joint area were significantly influenced primarily by the texture, followed by the laser power, and finally the interaction time. The optimal combination allowed the realization of joints whose maximum shear force reached around 750 N for polypropylene and around 2200 N for polyamide, achieving respectively 60% and 53% of the tensile force of the polymer base materials. [ABSTRACT FROM AUTHOR]

Electromagnetic welding, also referred to as magnetic pulse welding, is a solid-state welding method utilized for joining two distinct materials through high velocity impact. The direct fusion of stainless steel with titanium poses various difficulties owing to the absence of metallurgical compatibility and the occurrence of brittle intermetallic compounds such as FeTi and CrTi. To tackle these challenges, a sustainable, low heat input method like impact welding was applied to address the metallurgical compatibility of the two metals. In this study, a new technique involving aluminum foil, silver foil, and nitinol powder as intermediary materials was investigated to establish a fresh bimetallic structure between Ti-SS304L. Thorough analysis of microstructures, interface formations, and reactions was conducted using scanning electron microscopy and X-ray diffraction. The outcomes showcased successful prevention of intermetallic phase formation through the incorporation of these intermediary materials. Microhardness measurements indicated the absence of brittle FeTi and CrTi phases at the welding interface. Additionally, the weld interface was observed to be situated amid two intermetallic layers at the Ti-SS304L interface, ensuring resistance against corrosion. This inventive method not only averted the creation of harmful intermetallic compounds but also bolstered the overall strength and corrosion resilience of the joint between titanium and stainless steel. The micro hardness obtained at Ti-SS304L interface is 305 Hv and also improved 20% at interface of interlayer materials. [ABSTRACT FROM AUTHOR]

Surface roughness and wettability, which characterize the texture formed on the implant surface, are critical features for the functionality of the implant. Laser texturing is a promising processing method because of the advantages it provides in creating a particular surface topography on the surface of a metallic implant material with a nanosecond pulsed laser beam. Different experimental combinations were created using a fiber pulsed marking device on the surface of AISI 316LVM implant material using the hatch strategy; textures depending on the scan speed, frequency, and hatch distance were created on the surface. The surface roughness and wettability evaluated the effects of parameters on the texture form. Based on the experimental and statistical results, while the scan speed was the most significant parameter affecting the wettability behavior and surface roughness, the hatch strategy and frequency also affected the surface roughness to some extent. Many textured surfaces showed super-hydrophilic behavior with a contact angle of 0 ∘ . It has been determined that surface textures with the same or close roughness values did not exhibit the same wettability behavior. The lowest surface roughness of 2 μ m with a 1 3 2 ∘ contact angle was obtained at a hatch strategy of 0 ∘ / 9 0 ∘ , a scan speed of 900 mm/s, a frequency of 100 kHz, and a hatch distance of 0.03 mm. Three-dimensional surface images show that while many craters formed the surface textures, overlapping consecutive beams and hatch strategies significantly affected the surface topography. [ABSTRACT FROM AUTHOR]

Phase transformations in cold-rolled (CR) 304L austenitic stainless steel were studied using different techniques, including dilatometry, X-ray diffraction and scanning electron microscopy. During continuous annealing, the dilatometric measurements indicated that the evolution of the deformed microstructures led to an important anomaly constituted of two contractions. Quantitative processing of the X-ray diffraction results allowed the determination of the temperature-dependence of α′-martensite and austenite (γ), phase fractions, dislocations density and lattice strains on heating to 900°C. It is demonstrated that the first contraction is due to the recovery of α′- and γ-phases. In this temperature range, it is suggested that the recovery in CR γ has caused the growth of surrounding α′ particles which competes with the reversion of the smallest α′ particles. The second contraction, on the other hand, has been attributed to the α′ reversion and recrystallization in CR γ regions. [ABSTRACT FROM AUTHOR]

Via high-throughput first principle calculations based on density functional theory (DFT), doping elements that can improve the corrosion resistance of stainless steel bipolar plates' passivation layer in PEMFCS working environment were screened. Calculation models were constructed based on the (10 12) facet of Cr2O3and 48 elements were doped and 228 doping structures were considered. According to the doping structure and displacement energy, the doping elements were divided into 4 doping types, so that different adsorption and vacancy schemes were adopted. Then the effects of each doping element on the work function, F adsorption energy and Cr/O vacancy formation energy were calculated. The calculation result shows that C, N, In, and Ru can improve all the corrosion resistance parameters of the stainless steel passivation layer; Au, Rh, Pt, Ir, Co and Ni can also effectively improve the corrosion resistance, but there are problems such as price or harm to the proton membrane; Ag, Cu, Sn, and Ge can inhibit vacancy formation and F adsorption, but reduce the work function; Zn can improve the work function and inhibit F adsorption. In addition, the calculation of the electronic density of states shows that the stable bonding formed between the doping atom and the Cr atoms is an important factor for the improvement of the corrosion resistance parameters. [ABSTRACT FROM AUTHOR]

The chemical components and mechanisms underlying the toxicity and adverse health effects of particulate matter (PM) in the atmosphere have not been fully elucidated. After designing a small, openable, stainless steel cyclone to collect PM samples effectively in powder form for use in toxicological experiments, we evaluated its performance. We compared it with a commercially available aluminum cyclone of similar dimensions, but which is unopenable. The aerodynamic cutoff diameter of the openable cyclone was found by experimentation to be approximately 0.2 µm at a flow rate of 90 L min−1, which is comparable to the unopenable commercial cyclone. The sampling yields, representing the fraction of obtained sample mass relative to the total mass of PM with aerodynamic diameter smaller than 2.5 μm (PM2.5) drawn into the sampler, were approximately 1.3 times higher, on average, for the openable cyclone than for the unopenable cyclone. The openable design of the cyclone might contribute to a marked increase in the finally obtained amounts of PM samples. Analyses of metal concentrations in the PM samples collected simultaneously using the stainless steel openable cyclone and aluminum unopenable cyclone suggest that the stainless steel cyclone is less likely than the aluminum cyclone to cause sample contamination from its material. The openable cyclone developed for this study facilitates the effective collection of powder-form PM samples suitable for use in toxicological experiments. [ABSTRACT FROM AUTHOR]

For biomedical applications, hydroxyapatite and carbon nanotubes are currently being applied over duplex stainless steel (DSS) alone in order to increase corrosion resistance and biocompatibility. A composite of hydroxyapatite and multi-walled carbon nanotubes was used to improve biocompatibility, osseointegration, and corrosion resistance on 2205 DSS using electrophoretic deposition. The study investigates the effects of potential and time on the properties of the deposited layer in order to determine electrophoretic deposition factor values that are appropriate. The coating properties and effective groups of the phase resulting from this process are determined by Fourier transform infrared spectroscopy and X-ray diffraction. The antibacterial properties of E. coli bacterial strains are investigated for the coated layer. The adhesion between the hydroxyapatite and multi-walled carbon nanotube layers on the 2205 duplex stainless steel substrate was qualitatively evaluated using the adhesive tape test. It was found that the optimal suspension, which consists of 65 weight percent hydrogen acetate and 35 weight percent multi-walled carbon nanotubes, had a homogeneous morphology, a thick structure, and no cracks when coated at 50 V for two minutes. [ABSTRACT FROM AUTHOR]