Stainless Steel Alloy Research Articles

Additive manufacturing of a new non-equiatomic high-entropy alloy with exceptional strength-ductility synergy via in-situ alloying

Equiatomic high-entropy alloys (HEAs) fabricated by additive manufacturing (AM) have gained increasing attention since they present superior mechanical properties over their counterparts made by traditional synthesis routes. However, few studies have investigated AM of non-equiatomic HEAs, although this type of HEAs showing excellent mechanical properties. In this paper, we additively manufactured a novel non-equiatomic FeCoCrNi HEA via in-situ alloying 316L stainless steel and CrCoNi medium-entropy alloy. Besides the fine grain size (9 μm) and high dislocation density (3.8 × 1014 m−2), we observed unexpected high-intensity of hybrid crystal-amorphous precipitates, which have never been reported in NiCoCr-based alloys made by AM. These unique microstructures led to exceptional combination of strength (561 MPa) and elongation (41 %) exceeding those of additively manufactured equiatomic FeCoCrNi HEAs. Our observation from EBSD, TEM and atomistic simulations reveals a group of deformation mechanisms of stacking faults, deformation twins, TB-dislocation and dislocation-precipitates interactions. Our findings not only provide new insights into AM of non-equiatomic HEAs via in situ alloying, also shed lights on understanding the microstructure-properties relationship of non-equiatomic HEAs fabricated by AM.

Exploring Advanced Functionalities of Carbon Fiber-Graded PEEK Composites as Bone Fixation Plates Using Finite Element Analysis.

This study aims to address the challenges associated with conventional metallic bone fixation plates in biomechanical applications, such as stainless steel and titanium alloys, including stress shielding, allergic reactions, corrosion resistance, and interference with medical imaging. The use of materials with a low elastic modulus is regarded as an effective approach to overcome these problems. In this study, the impact of different types of chopped carbon fiber-reinforced polyether ether ketone (CCF/PEEK) functionally graded material (FGM) bone plates on stress shielding under static and instantaneous dynamic loading was explored using finite element analysis (FEA). The FGM bone plate models were established using ABAQUS and the user's subroutine USDFLD and VUSDFLD, and each model was established with an equivalent overall elastic modulus and distinctive distributions. The results revealed that all FGM bone plates exhibited lower stress shielding effects compared to metal bone plates. Particularly, the FGM plate with an elastic modulus gradually increased from the centre to both sides and provided maximum stress stimulation and the most uniform stress distribution within the fractured area. These findings offer crucial insights for designing implantable medical devices that possess enhanced mechanical adaptability.

High-temperature dynamic corrosion mechanisms of austenitic stainless and carbon steels in nitrates for concentrating solar power

Abstract: In this paper, to simulate the dynamic corrosion mechanisms of metals exposed to a high-temperature molten salt mixture of NaNO3–KNO3, the experimental samples made of commonly used stainless steel alloys such as 304 (with/without welds) and Q275 were suspended, along with stirring blades, in a specially designed stirred kettle to obtain their corrosion characteristics. For the experimental samples, the Q275 surface exhibited significant quantities of Fe3O4 and Fe2O3, while 304 generated FeCr2O4, Cr2O3, and MgFe2O4 with protective effects. The microstructure of the welding zone in 304 exhibited considerable disparities compared to that of the base material, consequently leading to augmented susceptibility towards localized corrosion. The uneven distribution of chromium in the welding zone resulted in intergranular corrosion and alterations in the crystal structure. Moreover, experimental studies have demonstrated that NO3- in the molten salt undergoes decomposition to generate oxygen ions, which contribute to the corrosion reaction. Notably, under all test conditions, the corrosion rate of samples exhibited the following ranking: 304 (without welds) < 304 (with welds) < Q275.

Exploiting the effect of PEO parameters on the surface of AISI 1020 low-carbon steel treated in a TaOH-rich electrolyte

This study used PEO treatment and a TaOH-rich electrolyte to coat AISI 1020 low-carbon steel to enhance its anti-corrosion and wear properties, targeting its usage as a medical device. The effect of time, duty cycle, frequency, and Ta(OH)5 concentration on the chemical and phase composition, topography, wettability, and roughness of the obtained coatings were addressed. The results indicated that the Fe-based oxide coatings had a rough and super-hydrophilic surface. The phase composition of the coatings was formed mainly of Ta2O5, hematite (Fe2O3), and a minor amount of rust (Fe(OH)2), with the chemical analyses also indicating the presence of some absorbed molecules. Once the best PEO parameters were established (200 V, 5 min, 60 %, 1000 Hz, and 40 g/L Ta(OH)5), the previous mechanical, corrosion, and wear tests evidenced the positive effect of the chemical species deposited in the surface when compared to the substrate. In this way, PEO treatment applied on AISI 1020 low-carbon steel in a TaOH-rich electrolyte can be an adequate alternative to produce low-cost materials for medical devices, especially as a potential substitute for stainless steel and titanium-based alloys in surgical instruments.

Welding investigation of Hastelloy C-276 and parametric optimization using integrated MRA-TLBO algorithm during A-TIG process

A-TIG welding is a modified form of GTAW process that has become popular due to its ability to create high-quality welded joints with minimal cracks and distortion. This technique is commonly used to join various metals, including stainless steel, aluminum, titanium, and nickel alloys like Hastelloy C-276, which is used in fabrication of complex components across marine, nuclear, aerospace, and chemical industries. In this investigation, A-TIG welding of Hastelloy C-276 was studied using three parameters - welding current, welding speed, and gas flow rate - at three distinct levels. The impact of these parameters were analyzed on two responses, namely penetration depth and width of weld. Macrostructural investigation, sensitivity analysis, and parametric studies revealed that welding current (I) had the most influence, followed by speed of welding (S) and flow rate of gas(G). Full quadratic multiple regression analysis-based models were developed for both responses, which were found to be suitable with a higher coefficient of determination and an average percentage error of 2.165% and 2.624%, respectively. Additionally, a teaching learning based optimization algorithm was integrated with these models to identify the most effective A-TIG parameter combination for higher penetration depth and lower weld width. The MRA-TLBO integrated approach resulted in an optimal parametric combination of I (170A), S (180 mm min−1), and G (11.37 l min−1) that resulted in a penetration depth and weld width of 4.503 mm and 4.684 mm, respectively. Validation at this optimal setting showed an improvement of 3.365% and 1.284% for weld width and penetration depth, respectively, suggesting the robustness of the developed methodology.

Development of occlusal canting identifying tool: verification, reliability and validation assessment

IntroductionOcclusal cant (OC) is a malocclusion trait that lacks accurate clinical assessment methods. The occlusal canting identifying tool (OCIT) was invented and patented as a clinical tool to accurately identify and quantify the degree of maxillary OC. This study aimed to 1) develop a prototype of the OCIT, 2) verify the functionality of the OCIT and 3) assess the validity and reliability of the OCIT.Materials and methodsA patented OCIT design was revised, and the dimensions were finalized, followed by a three-dimensional conceptual prototype design that was reviewed and approved by the inventors. Verification was performed using a digital angle gauge to determine the accuracy of the bubble level as well as the angle between the bite plate and the protractor. For laboratory validation, 40 orthodontists measured the simulated OC at (0°, 2°, 4°, 6° and 8°) on five phantom heads using the OCIT. A reliability assessment of the tool was performed in three occasions by one orthodontist using the same laboratory settings.ResultsThe OCIT was prototyped from a medical-grade stainless steel alloy (316 L). Verification assessment revealed that the accuracy error of the bubble level (0.316° ± 0.028°) was statistically significant but clinically insignificant, while that of the angle between the bite plate and protractor (0.100° ± 0.050°) was statistically insignificant. Validation assessment showed high validity of the OCIT with no statistically significant difference between the OCIT and the reference values, having more errors in identifying smaller OC degrees compared to larger OC degrees. The intraclass correlation coefficient indicated the high reliability of the OCIT.ConclusionThe OCIT was verified and proven to be a valid and reliable clinical tool that accurately evaluates the degree of OC.

Investigation of the Chemical Composition, Microstructure, Density, Microhardness, and Elastic Modulus of the New β Ti-50Nb-xMo Alloys for Biomedical Applications.

β-type titanium alloys with a body-centered cubic structure are highly useful in orthopedics due to their low elastic modulus, lower than other commonly used alloys such as stainless steel and Co-Cr alloys. The formation of the β phase in titanium alloys is achieved through β-stabilizing elements such as Nb, Mo, and Ta. To produce new β alloys with a low modulus of elasticity, this work aimed to produce our alloy system for biomedical applications (Ti-50Nb-Mo). The alloys were produced by arc-melting and have the following compositions Ti-50Nb-xMo (x = 0, 3, 5, 7, and 12 wt% Mo). The alloys were characterized by density, X-ray diffraction, scanning electron microscopy, microhardness, and elastic modulus. It is worth highlighting that this new set of alloys of the Ti-50Nb-Mo system produced in this study is unprecedented; due to this, there needs to be a report in the literature on the production and structural characterization, hardness, and elastic modulus analyses. The microstructure of the alloys has an exclusively β phase (with bcc crystalline structure). The results show that adding molybdenum considerably increased the microhardness and decreased the elastic modulus, with values around 80 GPa, below the metallic materials used commercially for this type of application. From the produced alloys, Ti-50Nb-12Mo is highlighted due to its lower elastic modulus.

Evaluation of shielding and interaction properties of different stainless steel alloys for nuclear power plant shielding

This study evaluated the gamma and neutron-shielding parameters, electron and charge particles’ interaction properties of three different stainless steel-based alloys (2507SS, 304SS and AISI1018) with densities of 7.82, 7.81 and 7.82, respectively for deployment in nuclear reactor construction. Gamma shielding parameters were evaluated with Phy-X/PSD, Py-MLBUF and GRASP computer programs within the energy range of 0.2 MeV to 15 MeV. The relative deviations (RD %) between two of these computational platforms were calculated. Fast Neutrons Effective Removal Cross-Sections (FNRCS) and Macroscopic Removal cross-section (MRCS) values for fast neutrons were calculated with Phy-X/PSD and MRCS software, while thermal/fast neutron attenuation factors were calculated with NGCals software. The continuous-slowing-down approximation (CSDA) range and total stopping power (TSP) values of H+ and He++ ions were estimated with SRIM Monte Carlo code in a wide energy range of 1–20 MeV. The projectile range of electrons was computed with ESTAR NIST software within the kinetic energy of 0.01–1000 MeV. Gamma-ray, thermal neutron and fast neutron transmission factors (TFs) values were calculated for all samples for a range of well-known energies. From the obtained results, all evaluated parameters were dependent on the composition of shielding materials, the type of radiation and the photon energy of the radiation. The maximum MAC values obtained from the three alloy samples are 0.1505 cm2/g for 2507SS, 0.1453 cm2/g for 304SS and 0.1459 cm2/g for AISI1018 at 0.02 MeV. These results projected 2507SS as a better shielding alloy when compared with other investigated alloy samples. Considering the closeness of densities of investigated alloy samples the shielding and interaction properties of all alloy samples gave excellent and similar results implying that all investigated alloys will effectively serve as a radiation-shielding material in a nuclear reactor.

Inhibition effect of copper-bearing metals on arterial neointimal hyperplasia via the AKT/Nrf2/ARE pathway in vitro and in vivo.

In-stent restenosis can be caused by the activation, proliferation and migration of vascular smooth muscle cells (VSMCs), which affects long-term efficacy of interventional therapy. Copper (Cu) has been proved to accelerate the endothelialization and reduce thrombosis formation, but little is known about its inhibition effect on the excessive proliferation of VSMCs. In this study, 316L-Cu stainless steel and L605-Cu cobalt-based alloy with varying Cu content were fabricated and their effects on surface property, blood compatibility and VSMCs were studied in vitro and in vivo. CCK-8 assay and EdU assay indicated that the Cu-bearing metals had obvious inhibitory effect on proliferation of VSMCs. Blood clotting and hemolysis tests showed that the Cu-bearing metals had good blood compatibility. The inhibition effect of the Cu-bearing metals on migration of cells was detected by Transwell assay. Further studies showed that Cu-bearing metals significantly decreased the mRNA expressions of bFGF, PDGF-B, HGF, Nrf2, GCLC, GCLM, NQO1 and HO1. The phosphorylation of AKT and Nrf2 protein expressions in VSMCs were significantly decreased by Cu-bearing metals. Furthermore, it was also found that SC79 and TBHQ treatments could recover the protein expressions of phospho-AKT and Nrf2, and their downstream proteins as well. Moreover, 316L-Cu stent proved its inhibitory action on the proliferation of VSMCs in vivo. In sum, the results demonstrated that the Cu-bearing metals possessed apparent inhibitory effect on proliferation and migration of VSMCs via regulating the AKT/Nrf2/ARE pathway, showing the Cu-bearing metals as promising stent materials for long-term efficacy of implantation.

Insertion torque, flexural strength and surface alterations of stainless steel and titanium alloy orthodontic mini-implants: an in vitro study.

This study aimed to compare the insertion torque (IT), flexural strength (FS) and surface alterations between stainless steel (SS-MIs) and titanium alloy (Ti-MIs) orthodontic mini-implants. Twenty-four MIs (2 x 10 mm; SS-MIs, n = 12; Ti-MIs, n = 12) were inserted on artificial bone blocks of 20 lb/ft3 (20 PCF) and 40 lb/ft3 (40 PCF) density. The maximum IT was recorded using a digital torque meter. FS was evaluated at 2, 3 and 4 mm-deflection. Surface topography and chemical composition of MIs were assessed by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). General linear and mixed models were used to assess the effect of the MI type, bone density and deflection on the evaluated outcomes. The IT of Ti-MIs was 1.1 Ncm greater than that obtained for the SS-MIs (p= 0.018). The IT for MIs inserted in 40 PCF test blocks was 5.4 Ncm greater than that for those inserted in 20 PCF test blocks (p < 0.001). SS-MIs inserted in higher density bone (40 PCF) had significantly higher flexural strength than the other groups, at 2 mm (98.7 ± 5.1 Ncm), 3 mm (112.0 ± 3.9 Ncm) and 4 mm (120.0 ± 3.4 Ncm) of deflection (p< 0.001). SEM evidenced fractures in the Ti-MIs. EDS revealed incorporation of 18% of C and 2.06% of O in the loaded SS-MIs, and 3.91% of C in the loaded Ti-MIs. Based on the findings of this in vitro study, it seems that SS-MIs offer sufficient stability and exhibit greater mechanical strength, compared to Ti-MIs when inserted into higher density bone.

Phase field simulation of intra/intergranular pore morphology evolution of neutron-irradiated austenitic stainless steel

Intergranular or intragranular anisotropic pores can be easily observed in the FCC structure of nuclear reactor core structural materials, such as austenitic stainless steel or nickel-based alloys. Austenitic stainless steel contains a certain amount of nickel(Ni), Ni undergo transmutation reaction under neutron irradiation to produce helium. Helium combines with vacancy and continuously absorbs more helium and vacancy, evolving into underpressure pores filled with a small amount of helium. The morphology of pores is influenced by both the surface anisotropy of the crystal and grain boundary characteristic because pores nucleation predominantly occurs at grain boundaries. The swelling effect caused by pores and the embrittlement effect of high temperature helium are related to the morphology, size and distribution of pores. The phase field method can couple multiple physical fields and accurately describe the effects of material microscopic defects on pores. In this study, we use establish a free energy functional coupling between crystal plane anisotropy and pore-grain boundary interactions, using phase field methods to simulate pores’ evolution and morphology. Our results demonstrate that helium gas induces pore nucleation, with higher concentrations leading to shorter incubation period, faster nucleation rate, and greater growth rate. Grain boundaries act as heterogeneous nucleation sites for helium pores, leading to the formation of pores along these boundaries and high-density diffusion pores within grains. The intragranular pores exhibit anisotropic characteristics regulated by interfacial energy's anisotropic modulus, the strength of the anisotropy, and crystal orientation. The high-density intergranular pores interact significantly and are influenced by grain boundaries, while the anisotropic morphology is negligible. Additionally, it has been observed that the pores located at the middle of grain boundaries tend to exhibit an elliptical shape. The stress inside the pores that contain a small amount of helium gas is negative, which is lower than the value in the matrix. The findings presented herein align well with experimental results and have implications for life prediction models for service components as well as core material design.

To Evaluate the Effect of Prophylactic Agents on the Surface Morphology of Different Orthodontic Wires at Different Temperatures: An In vitro Study

Aim and Objective: The aim and objective are to evaluate the effect of prophylactic agents on the surface morphology of different types of orthodontic wires of different dimensions at two different temperatures. Materials and Methods: Stainless steel (SS), NiTi, and titanium-molybdenum alloy (TMA) wires of 0.016 inch round and 0.017 inch × 0.025-inch dimensions were immersed in prophylactic agents such as 0.2% NaF, 0.2% CHx and 1.23% APF for 1.5 h at 37°C and 45°C. A one-way analysis of variance, Bonferroni test, and intraclass correlation coefficient test was performed to eliminate the bias. Scanning electron microscope was used to evaluate the surface characteristics of wire and quantitative analysis was performed using ImageJ software. Results: Highest corrosion can be seen on TMA wires of 0.016 inch and 0.017 inch × 0.025 inch when exposed to 1.23% APF gel at 45°C and lowest corrosion can be seen on SS wires of 0.017 inch × 0.025 inch when exposed to 0.2% NaF mouthwash at 37°C. Conclusion: The results suggest that sodium fluoride is the mouthwash of choice when used with all three types of orthodontic wires used for different orthodontic purposes and APF gel should not be recommended when TMA wires are used at high temperatures as it causes corrosion which can lead to increased friction.

Optimizing Orthopaedic Bone Plates for Directed Energy Deposition with Generative Design and Topological Optimization Approaches

Directed Energy Deposition (DED), a metal additive manufacturing technique, shows promise for future orthopaedic applications, especially in bone plate manufacturing. The need for patient-specific solutions in orthopaedics is growing, driven by the limitations of traditional bone plates made from stainless steel or titanium alloys and the rising incidence of complex fractures. This paper explores the design of orthopaedic bone plates using Generative Design (GD) and Topological Optimization (TO), aimed at eventual production through DED. By focusing on design, the research addresses challenges like stress shielding, caused by the modulus disparity between conventional plate materials and natural bone. Significant findings include mass reductions of 43.7% and 44.2% for GD designs GD1 and GD2, respectively, and a 36% reduction for the TO design TO1, enhancing biomechanical performance with improved strain values. The findings demonstrate GD’s effectiveness in generating anatomically congruent implants, showcasing advancements in personalized care and fracture treatment. The integration of GD and DED within the Design for Additive Manufacturing (DfAM) framework offers a promising pathway for future research focused on refining patient-specific designs and manufacturing processes, aligning with the evolving needs of orthopaedic treatments.

Optimizing and Redesigning the Vertical Milling Fixture for Friction Stir Welding of Aluminium Alloy (Al 6061)

Friction stir welding is a kind of solid-state fusion process for welding like or unlike metals. Established and patented by “The Institute of Welding” in the UK in December 1991, it involves using a compressive force applied by a conventional milling machine to make contact with work-pieces. The work-pieces are one or the other revolving or moving proportional to a pin tool, generating the heat necessary for atomic diffusion and thereby uniting the material at the edges. FSW can be functional in a variety of materials, together with stainless steel, aluminium, and various alloys. The process typically takes place on vertical milling machines, requiring a vertical milling fixture to firmly hold the plates being welded. In this paper, vertical milling holding setup and fixture for FSW procedures on vertical milling machines are established. Materials such as aluminium and aluminium alloy (Al 6061) are analyzed for their suitability in FSW operations, to identify the best material for the process. Additionally, there is potential for extending the FSW process to plastics and similar materials. Friction stir welding offers significant advantages in terms of weld quality, strength, and versatility across a range of industries, making it a versatile option for solid-state joining processes.

Ocena tehnika mašinskog učenja za Nd - IAG Laser i TIG zavareni nerđajući čelik 304

Nd: YAG Laser and Tungsten Inert Gas (TIG) welding processes are the most promising joining techniques used for stainless steel (SS) alloys due to their significant weld characteristics. In this study, the effect of two process parameters (weld power and travel speed) on the mechanical properties (ultimate tensile strength and microhardness) of the weldment is investigated. Two different machine learning techniques, namely Adaptive Neuro-Fuzzy Inference System (ANFIS) and Unified Convolutional Neural Network (UCNN) are also evaluated for prediction of mechanical properties and defect detection through the image processing technique, respectively. A correlation has been performed between these two machine learning approaches with the experimental values. The training data sets are developed for the machine learning techniques, and the obtained results of (ANFIS) and (UCNN) models are related to the actual experimental values. The output of both developed models (ANFIS &amp; UCNN) showed a good agreement with the actual experimental test results. The predicted tensile and microhardness values from the (ANFIS) model were found to greatly agree with the Peak Signal-to-Noise Ratio (PSNR) values from the (UCNN) model. However, owing to the increase in the applications of welding processes in industries, the utilization of machine learning techniques would be more efficient when compared with the other traditional methods that are being adopted.

Experimental investigation on corrosion resistance and tribological properties of steel coated with glass-reinforced polymer

This work presents a comprehensive electrochemical corrosion analysis conducted on steel coated with glass-reinforced polymer (GRP), low alloy steel and stainless steel, focusing on their performance in a simulated aggressive environment (3 % NaCl). The corrosion rates were established and the corrosion mechanisms governing each material's behaviour were elucidated. By comparing the electrochemical behaviour of these materials, we aim to evaluate the efficacy of GRP coatings in preventing corrosion compared to conventional metallic materials used for pipeline systems. Furthermore, in addition to the corrosion analysis, the coefficient of friction determination between the GRP-coated steel and 25CrMo4 (EN 10083-3) steel was conducted to assess their tribological compatibility. Understanding the frictional behaviour between these materials is essential for optimising pipeline performance, minimising wear and ensuring operational efficiency in dynamic environments encountered in the petroleum and gas industry. The study includes, also, an evaluation of cumulative linear wear to quantify the material loss. This comprehensive approach provides a complete understanding of the interplay between corrosion resistance and mechanical durability.

A Study On Stress Management Among Employees Towards Alloy Industries With Reference To Coimbatore

In order to boost strength or corrosion resistance, two or more metallic components are mixed to form an alloy, which is a type of metal. A metallic material composed of two or more elements is called an alloy, sometimes known as a compound or a solution. Although the non-metal carbon is an essential part of steel, the constituents of alloys are normally metals. Alloys are often created by melting the mixture of components. According to customer specifications and drawings, Alloys Industries manufactures and exports a variety of machined and un-machined castings made of Carbon Steel, Stainless Steel, Low Alloy Steel, Heat Resistant Steel, Martensitic Stainless Steel (CA6NM), Precipitated Hardened Steel (CB7Cu-1), Nickel Alloy, and Duplex Stainless Steel. The phrase "stress managements" is broad and includes training, facilitation, and education about the effects that stress has on an individual or group. The study of stress management fosters and encourages the development of coping mechanisms. Employees' physiology and psyche are stressed out by organisational elements such management-labor relations, working conditions, resource distribution, the role of trade unions, employee behaviours, etc. The working practises and policies of an organisation are among its most important influencing variables. This study examined the occupational stress experienced by Alloy Industries in Coimbatore, employees in great detail.

Flux and estimated spectra from a low-intensity laser-driven X-ray source

Abstract Laser-driven X-rays as probes for high-energy-density physics spans an extremely large parameter space with laser intensities varying by 8 orders of magnitude. We have built and characterized a soft X-ray source driven by a modest intensity laser of 4 × 1013 W/cm2. Emitted X-rays were measured by diamond radiation detectors and a filtered soft X-ray camera. A material-dependence study on Al, Ti, stainless steel alloy 304, Fe, Cu and Sn targets indicated 5-μm-thick Cu foils produced the highest X-ray yield. X-ray emission in the laser direction and emission in the reverse direction depend strongly on the foil material and the thickness due to the opacity and hydrodynamic disassembly time. The time-varying X-ray signals are used to measure the material thinning rate and is found to be ∼1.5 μm/ns for the materials tested implying thermal temperature around 0.6 eV. The X-ray spectra from Cu targets peaks at ∼2 keV with no emission &gt;4 keV and was estimated using images with eight different foil filters. One-dimensional hydrodynamic and spectral calculations using HELIOS-CR provide qualitative agreement with experimental results. Modest intensity lasers can be an excellent source for nanosecond bursts of soft X-rays.

Improving surface integrity and wear resistance of selective laser melted 316L stainless steel using ultrasonic nanocrystal surface modification

In this study, ultrasonic nanocrystal surface modification (UNSM) was employed to process 316L stainless steel fabricated using selective laser melting (SLM). The surface integrity, microstructure evolution, and mechanical behavior of this alloy before and after UNSM treatment were systematically characterized. The results show that the surface integrity and wear resistance of the alloy has been significantly improved due to the synergistic effect of grain refinement, work hardening, and beneficial compressive residual stresses that resulted from UNSM processing. The effect of the gradient structure and residual stress introduced by UNSM processing on the strengthening mechanism and its effect on friction and wear behavior have been discussed. The improved surface finish, the grain refinement layer, and the presence of compressive residual stress of the UNSM SLM 316L stainless steel alloy successfully demonstrated UNSM to be a promising post-processing surface treatment technology to enhance the fatigue performance of additively manufactured metallic materials.

Simple fabrication of anisotropic slippery lubricant-infused surface for directional transportation and anti-corrosion by metal-metal laminated composites

Slippery lubricant-infused surfaces with anisotropy for directional transportation have been widely researched and fabricated. However, the preparation of the required surface morphology remains complex and challenging. Inspired by the laminated structure found on natural shell nacre and slippery characteristics of nepenthes, a simple and universal method was provided to fabricate anisotropic slippery lubricant-infused surface. 304/TC4 metal-metal laminated composites were prepared by diffusion bonding 304 stainless steel and TC4 titanium alloy foils. A regular micro array with grooves was obtained through simple chemical etching. The widths of grooves and bulges, as well as the depths of grooves could be adjusted as needed. After the chemical modification, the lubricant was infused into grooves to obtain anisotropic slippery lubricant-infused surfaces. The directional transportations along the grooves of water droplet in air and bubbles underwater were achieved on the fabricated surfaces. Furthermore, the achieved surfaces demonstrated outstanding performance in anti-corrosion and anti-fouling. A noteworthy advantage of using laminated composites to fabricate anisotropic slippery lubricant-infused surfaces lies in its simplicity, universality, and repeatability. Based on the previous reports about laminated composites, the structure with grooves can been obtained by simple chemical etching. This method is suitable for various materials, including metal, ceramic, carbon material, and polymers. It has great potential application in water collection, directional transportations, anti-corrosion and anti-fouling.