316L Steel Substrates Research Articles

Effect of laser power during laser powder bed fusion on microstructure of joining interface between Tungsten and AISI 316L steel

This study investigates the deposition of tungsten (W) onto a 316L steel substrate by laser powder bed fusion (L-PBF), to optimize process parameters and analyze the interface between W and 316L. To obtain high-density W structure (98.89%), the optimal laser power was 350 W, and scan speed was 500 mm/s, but these parameters cause significant dilution of W in the W-316L interface; as a result, Fe7W6 intermetallics form, despite L-PBF being a non-equilibrium solidification process. These intermetallics which are brittle could degrade joint strength. By reducing laser power below 250 W, the dilution of W can be mitigated, and potentially minimize formation of intermetallics and increase joint stability for advanced manufacturing applications.

Study of amorphous alumina coatings for next-generation nuclear reactors: High-temperature in-situ and post-mortem Raman spectroscopy and X-ray diffraction

The present work focuses on the investigation of the thermal stability and structural integrity of amorphous alumina coatings intended for use as protective coatings on cladding tubes in Generation IV nuclear reactors, specifically in the Lead-cooled Fast Reactor (LFR) type. High-temperature Raman spectroscopy and high-temperature X-ray diffraction analyses were carried out up to 1050 °C on a 5 µm coating deposited by the pulsed laser deposition (PLD) technique on a 316L steel substrate. The experiments involved the in-situ examination of structural changes in the material under increasing temperature, along with ex-situ Raman imaging of the surface and cross-section of the coating after thermal treatments of different lengths. As it was expected, the presence of α-alumina was detected with the addition of other polymorphs, γ- and θ-Al2O3, found in the material after longer high-temperature exposure. The use of two structural analysis methods and two lasers excitation wavelengths with Raman spectroscopy allowed us to detect all the mentioned phases despite different mode activity. Alumina analysis was based on the emission spectra, while substrate oxidation products were identified through the structural bands. The experiments depicted a dependence of the phase composition of oxidation products and alumina’s degree of crystallization on the length of the treatment. Nevertheless, the observed structural changes did not occur rapidly, and the coating’s integrity remained intact. Moreover, oxidation signs occurred locally at temperatures exceeding the LFR reactor’s working temperature, confirming the material’s great potential as a protective coating in the operational conditions of LFR nuclear reactors.

Micromechanical Analysis of Metal-Ceramic Thin-Films on Steel Substrates

Thin-layered coatings on material surfaces can resist contact forces and provide protection against material wear. In this study, FeCrNi-Al2O3 composite coatings were prepared by electrodeposition onto a 316L steel substrate. The effects of electrodeposition cathode current density (3 A·dm−2, 5 A·dm−2, 7 A·dm−2 and 9 A·dm−2) and post annealing at 500°C in Ar atmosphere were investigated. An increase in deposition rate resulted in a rougher coating surface and a thicker coating at a constant deposition duration. Post-deposition heat treatment caused the surface roughness to increase because of the introduction of denser micro-cracks. Higher current densities improved adhesion and prevented angled cracks during scratching, while annealing led to scratching-induced failures at lower applied loads. FeCrNi-Al2O3 composite coatings showed higher hardness but lower Young's modulus compared to the steel substrate. The coating hardness is slightly enhanced by increasing the electrodeposition current density from 5 A·dm−2 to 9 A·dm−2, and a more significant increase is observed after annealing. However, the hardness is negatively impacted by the combined effect of annealing and higher current density. These findings demonstrate the importance of carefully balancing the electrodeposition current density and annealing conditions to achieve optimal coating properties. To optimize metal-ceramic composite coatings, it is crucial to investigate multiple process parameters that may interact with each other.

The influence of corrosive medium on the selected tribological properties of ZrSi-based nitride and oxynitride deposited on 316L stainless steel

Targeting to restore the function of load-bearing joints which are subjected to high levels of friction and wear during the normal activity, the aim of the current study was to assess the extent of the role played by the corrosive environment on the underlaying tribological mechanism. In this study we deposited by reactive cathodic arc evaporation technique ∼ 1 μm thick, stoichiometric ZrSi-based nitrides and oxynitrides coatings, either as monolayer or double-layer structure on 316L steel substrates. Tribological tests were conducted in dry and two commonly used corrosive environments: Ringer and 0.9 % NaCl solutions. We demonstrate that the ZrSiN and ZrSi(N,O) coatings improved the wear performance of 316L stainless steel in biological environments, reaching even ∼ 94 % improvement as compared with the bare substrate for the ZrSi(N,O) coating.

Hot Corrosion Behavior of Plasma-Sprayed WC-CoCr Coatings on AISI 316L Steel Substrate in Na2SO4-25% NaCl Salt Environment

This study investigates the hot corrosion resistance characteristics of plasma-sprayed WC-CoCr coatings deposited on AISI 316L stainless steel. Coated and uncoated samples were exposed to a fused Na2SO4-25%NaCl salt deposit at 700 °C in cyclic conditions for fifty thermal cycles. The corrosion kinetics were determined using a thermogravimetric method. To determine the hot corrosion rate, weight-change measurements were taken after every cycle. X-ray diffraction, energy dispersive spectroscopy, and scanning electron microscopy were performed on samples to examine the hot corrosion characteristics. With a fused salt deposit at 700 °C, the uncoated AISI 316L steel substrate samples experienced faster high-temperature oxidation as compared to coated samples. It was noticed that the uncoated steel substrate gained a little weight during the first few cycles, afterwards as the number of thermal cycles increased, the weight gain followed a linear kinetics. The WC-CoCr coating reduced the weight gain of steel substrate by about 75% in a corrosive salt environment. The plasma-sprayed WC-CoCr coatings had adhesion strength and microhardness of 10.8 ± 2.4 MPa and 410 ± 25 HV0.5, respectively. The hot corrosion-affected coatings displayed slow-scaling kinetics. The oxides of the coatings, formed at the surface were rich in chromium and tungsten. These oxides helped in providing hot corrosion resistance in the corrosive environment as they worked as obstacles to the penetration/diffusion of corrosive elements through coatings. The higher content of tungsten inside the coating promoted WO3 formation, which improved resistance to corrosion at elevated temperatures. Chromium in the coating caused the formation of spinel CoCr2O4 and Cr2O3 the spinel CoCr2O4 that emerged as an intermediate phase also contributes to the maintenance of corrosion resistance. Some oxides such as Fe2O3, FeCr2O4, and CoSO4 were found. Apart from that some traces of Na were also found.

Amorphous/quasi-amorphous CoCrMo-C coatings for improved electrochemical properties and tribocorrosion resistance of biomedical alloys

Coatings based on CoCrMo cobalt alloy have been designed to increase corrosion resistance of AISI 316L austenitic steel in body fluids. The CoCrMo-C coatings, with different carbon content (from 0 to 65 at.%), were synthesised by reactive magnetron sputtering of the medical CoCrMo (ISO 5832-12) alloy in the argon-acetylene atmosphere. Evolution of their structure, crystalline phase and chemical composition with increasing carbon fraction were investigated by X-ray diffractometry and X-ray photoelectron spectroscopy. Evaluation of corrosion resistance of CoCrMo-C films on 316L steel substrates was performed in Hanks' Balanced Salt Solution (HBSS) by means of electrochemical impedance spectroscopy and potentiodynamic polarisation tests. The studies have revealed high chemical inertness of all coatings. Passive/blocking layers formed on their surfaces exhibit a capacitive character, while their resistivity is nearly two orders of magnitude higher compared to the corresponding values obtained for the CoCrMo and 316L alloys tested under similar conditions. The CoCrMo-C coatings provide pitting corrosion protection for 316L austenitic steel. This is expected to extend the residence time of stainless steel in the tissue environment. The 316L/CoCrMo-C systems were also subjected to tribocorrosion tests in HBSS at three electrochemical potentials, i.e. at open circuit, cathodic, and anodic potential. A model was developed to relate the electrical values recorded during tribocorrosion experiments with the phenomena that characterize the coating wear process. It was found that the friction coefficient systematically decreased from 0.7 to 0.1 with increasing the carbon content under all potentials applied. The wear rate observed for majority of the coatings was lower than that for CoCrMo and 316L alloys. For the samples with the highest carbon content, the wear rate under oxidative conditions became even lower than for the cathodic potential.

Structure and properties of the TiN/ZnO coating obtained by the hybrid method combining PVD and ALD technologies on austenitic Cr-Ni-Mo steel substrate

TiN/ZnO hybrid coatings (combining PVD and ALD technologies) were applied on an AISI 316L steel substrate in the work presented here. For the ALD process, the number of cycles was changed to 500, 1000, and 1500, respectively. This work qualitative analysis using a scanning electron microscope, SEM, elemental analysis using an EDS spectrometer, and morphology studies using an atomic force microscope, AFM. Furthermore, mechanical properties including adhesion, abrasive wear resistance, and roughness were also investigated. Adhesion tests revealed the presence of fine cracks in the TiN/ZnO coating (number of ALD cycles 500) and no delamination. Corrosion tests were conducted in Ringer's solution simulating human body fluids by potentiodynamic and EIS methods. The Pe corrosion protection effectiveness of the tested coatings ranges from 86% to 48%. The hybrid TiN/ZnO hybrid coating produced by the PVD and ALD processes was shown to cause a significant increase in the corrosion resistance of samples made of 316L stainless steel.

The Technological Factors and Operating Conditions Influence on the Molybdenum Disulfide Coatings Tribological Properties

Molybdenum disulfide is a widely used solid lubricant operates successfully under extreme conditions such as vacuum, high or low temperatures, high loads etc. Magnetron sputtering is one of the most common method of application MoS2 coatings. It allows one to apply thin antifrictional films with high rate of purity on different substrates. The surface before application is usually prepared by abrasive processing. The aim of the work is to evaluate the magnetron deposition modes, substrate surface preparation, substrate roughness on the molybdenum disulfide coatings tribological properties. For the purpose mentioned a linearly reciprocating Ball-on-Flat (ASTM G133) Sliding Wear tests in vacuum (pressure less than 10-4 mbar) and high temperature (250 ¬¬¬0C) were conducted. The two different materials as a coating substrate was used (stainless steel and brass). The substrate surface was sandblasted. The coating surfaces structure after wear and chemical composition have been studied. The friction coefficient in vacuum at 250 °C was about 0.02–0.05. The least value was observed for the AISI 316L steel substrate treated by sandpaper and Ra 0.10 µm roughness coatings. The negative bias voltage (–20 V) during magnetron deposition leads to 16–42% lower coefficient of friction. Oxygen decreases the anti-friction properties.

Corrosion protection of stainless steel by a new and low‐cost organic coating obtained from cashew nutshell liquid

AbstractIn this work, the corrosion protection of 316L steel was promoted by an electro‐synthesized polymer obtained from the technical cashew nutshell liquid (t‐CNSL). Spectroscopic techniques confirmed the polymer formation. The polymer was dispersed in the ethyl acetate solvent and used to form coatings on 316L steel substrates. The coated samples were subjected to electrochemical tests in a saline environment. The coated electrode with poly(t‐CNSL) polymer was exposed to the corrosive medium for 24 days, and superior corrosion protection was observed compared with the uncoated sample. The open circuit potential measurements showed that the coated sample possessed a more positive corrosion potential when compared with the uncoated substrate. The electrochemical impedance spectroscopy results indicated that the coated electrode's polarization resistance (Rp) recorded ~1.0 MΩ cm2 after 24 days of exposure. A decrease in polarization resistance was observed with the exposure time due to the presence of micropores in the t‐CNSL coating. The polarization curves exhibited that the coated electrode with poly(t‐CNSL) has lower corrosion current density and less negative corrosion potential than the uncoated steel electrode. Therefore, t‐CNSL favors the manufacture of thin poly(t‐CNSL) coatings for corrosion protection purposes besides being a low‐cost material.

Investigations of CrN+Cr2O3/TiO2 coatings obtained in a PVD/ALD hybrid method on austenitic 316L steel substrate

The study investigated hybrid coatings CrN + Cr2O3/TiO2 type obtained using the hybrid PVD/ALD technology on a substrate made of Cr-Ni-Mo (316L) stainless steel. Coating of CrN + Cr2O3 was obtained by the Arc-PVD method. TiO2 using atomic layers deposition was investigated. It were deposited at a variable number of cycles from 200 to 1000 cycles at a constant temperature of 200 °C. Structural studies using scanning and transmission electron microscopy and atomic force microscopy were performed. The chemical composition analysis in the micro-regions was performed using EDS. The study of electrochemical properties was performed using potentiodynamic method and electrochemical impedance spectroscopy (EIS) in a 3.5% NaCl solution. As a result of the study, it was found that the best electrochemical properties were shown by hybrid coatings for which the TiO2 layer was obtained in 500 ALD cycles. Based on microscopic studies with diffraction and spectroscopic analysis, the structure of the tested coatings was related to electrochemical properties, and the influence of deposition conditions on corrosion resistance was explained. In addition, the tests were supplemented with tests of tribological properties and adhesion of coatings to the substrate.

AISI 316L stainless steel modification by surface alloy and a-C:H:SiOx coating synthesis

AISI 316L austenite stainless steel is often used in orthopedics, although metal particles and metal ions are the major weakness of metallic prostheses associated with the tissue inflammation and proliferation. This paper presents the surface modification of the AISI 316L steel substrate to reduce its wear and corrosion rate using a combination of two methods. For that, the titanium alloy is synthesized on the substrate surface using the magnetron sputtering and electron-beam treatment. The elemental and phase compositions of the surface are investigated by energy dispersive X-ray spectrometry and X-ray diffraction. The a-C:H:SiOx coating is deposited onto substrates with the surface alloy by plasma assisted chemical vapor deposition to significantly improve the mechanical, anti-corrosion and wear-resistant properties of AISI 316L austenite stainless steel. The mechanical properties and the surface of the obtained coating are examined by nanoindentation and optical microscopy, respectively. It is shown that substrates with the surface alloy and a-C:H:SiOx coating manifest stability to autoclave sterilization proven by the results of optical microscopy.

Investigation on Microstructure, Nanohardness and Corrosion Response of Laser Cladded Colmonoy-6 Particles on 316L Steel Substrate.

316L steel is predominantly used in manufacturing the components of high-pressure boilers, heat exchangers, aerospace engines, oil and gas refineries, etc. Its notable percentage of chromium offers resistance against corrosion and is mostly implemented in harsh environments. However, long-term exposure to these components in such environments can reduce their corrosion resistance property. Particularly at high temperatures, the oxide film formed on this type of steel reacts with the chloride, sulfides, sulfates, fluorides and forms intermetallic compounds which affect its resistance, followed by failures and losses. This work is focused on investigating the hardness, microstructure and corrosion resistance of the laser cladded Colmonoy-6 particles on the 316L steel substrate. The cladded specimens were dissected into cubic shapes and the microstructure present in the cladded region was effectively analyzed using the FESEM along with the corresponding EDS mapping. For evaluating the hardness of the cladded samples, the nanoindentation technique was performed using the TI980 TriboIndenter and the values were measured. The potentiodynamic polarization curves were plotted for both the substrate and clad samples at 0, 18, 42 and 70 h for revealing the corrosion resistance behavior. In addition, the EIS analysis was carried out to further confirm the resistance offered by the samples. The surface roughness morphology was evaluated after the corrosion process using the laser microscope, and the roughness values were measured and compared with the substrate samples. The result showed that the cladded samples experience greater hardness, lower values of surface roughness and provide better corrosion resistance when compared with substrate samples. This is due to the deposition of precipitates of chromium-rich carbide and borides that enhances the above properties and forms a stable passive film that resists corrosion during the corrosion process.

Structure and Properties of TiO2/nanoTiO2 Bimodal Coatings Obtained by a Hybrid PVD/ALD Method on 316L Steel Substrate.

This paper presents the synergy of the effect of two surface engineering technologies—magnetron sputtering (MS-PVD) and atomic layer deposition (ALD) on the structure and properties of 316L steel. Recent studies indicate that PVD coatings, despite their thickness of a few micrometers, have many discontinuities and structural defects, which may lead to pitting corrosion after time. Applying an ALD layer to a PVD coating seals its structure and contributes to extending the service life of the coating. Investigations of the structure and morphology of the produced layers were carried out using a scanning electron microscope (SEM) and atomic force microscope (AFM). In addition, the structure of the coatings was investigated on the cross-section using a scanning-transmission electron microscope S/TEM. The tribological properties of the materials studied were determined by the ball-on-disc method. The corrosion resistance of the tested materials was determined by the electrochemical potentiodynamic method by recording the polarization curves of the anodes. Additional information about the electrochemical properties of the tested samples, including the quality, their tightness, and their resistivity, was obtained by electrochemical impedance spectroscopy (EIS). In addition, the main mechanisms of corrosion and tribological wear were determined by SEM observations after corrosion tests and after tribological tests. The study showed that the fabrication of hybrid layers by MS-PVD and ALD techniques allows obtaining coatings with electrochemical properties superior to those of layers fabricated by only one method.

Evaluation of Corrosion Resistance of Thin Films Formed on AISI 316L Steel by Plasma Using Hastelloy as Cathodic Cage

Herein, the use of Hastelloy C‐276 as a cathodic cage for the deposition of thin films on the AISI 316L steel substrate by plasma is investigated. The films are processed through floating potential at 350, 375, 400, and 425 °C for 4 h, using a hydrogen–nitrogen mixture in the proportion of 40% and 60%, respectively. The thin films are investigated by X‐ray diffraction, scanning electron microscopy, Raman spectroscopy, and potentiodynamic polarization. The spectroscopy results point out the formation of different phases such as FeNi3, CrNi, and MoN1/2. Films acquired at 375 ºC present superior corrosion resistance with less negative corrosion potential (−0.020 V). The increase and decrease in FeNi3 and CrNi contents follow the improvement of the applied temperature, which is unbeneficial to the corrosion resistance of the films.

Mechanical behavior of YSZ coatings co-deposited with Al and Ag on AISI 316L via RF sputtering

This article presents nanohardness, coefficient of friction (COF), and wear of Yttria-stabilized zirconia coatings (YSZ) deposited on 316L steel substrates and co-deposited with Al and Ag. YSZ coatings were deposited via RF sputtering reactive phase technique. It is widely known that the RF sputtering technique produces stoichiometric coatings with high homogeneity and density. The average thickness of the coatings was 200 nm, and the X-ray diffraction study (XRD) showed the formation of alumina alpha (α-Al2O3) and metallic silver in the YSZ coatings deposited with Al and Ag, respectively. The mechanical properties were evaluated by means of nanoindentation, and the wear resistance was studied with pin-on-disk technique. The addition of Ag to the YSZ coatings led to decreased hardness, while the YSZ coatings deposited with Al presented an increased hardness. Finally, YSZ coatings deposited with aluminum and silver had the lowest friction coefficient, while Ag-YSZ coatings had a COF very similar to that obtained in YSZ coatings. The wear resistance test showed that YSZ coatings deposited with Al had lower volume loss compared to YSZ coatings deposited with Ag. The wear mechanism in the deposited coatings is analyzed.

Brazing TC4 titanium alloy/316L stainless steel joint with Ti50-xZrxCu39Ni11 amorphous filler metals

TC4 titanium alloy was brazed to 316L stainless steel with newly designed TixZr50-xCu39Ni11 amorphous filler metals. The effect of Zr content on the wettability of filler metals, interfacial microstructure and shear strength of the brazed joints was investigated. Precipitation behavior of submicron phase and fracture behavior of the brazed joints were analyzed. Increasing Zr content in filler metals first increased and then decreased the spreading area of filler metals on both TC4 titanium alloy and 316L steel substrates, and changed the primary phase in filler drops. Besides, residual filler metal layer was thickened due to the reduction of filler metal flowability. But the thickness of the transition zone decreased, particularly the α-Fe reaction layer, attributed to the attenuation of Ti diffusion from filler metal to 316L steel substrate. Submicron β-Ti phase precipitated near the FeTi/Fe2Ti interface, and there were orientation relationships among the submicron β-Ti phase, FeTi and Fe2Ti as follows: (110)FeTi||(110)β-Ti/[1(_)11]FeTi||[1(_)11]β-Ti and (100)FeTi||(100)β-Ti/[001]FeTi||[001]β-Ti. The shear strength of brazed joints first increased and then decreased with the peak value of 238 MPa at 22.2 at.% Zr. Stress concentration at FeTi/Fe2Ti interface and impossible orientation relationship between FeTi and Fe2Ti phases resulted in the brittle fracture at FeTi/Fe2Ti interface of the brazed joint.

Corrosion inhibition of 316L-type stainless steel under marine environments using epoxy/waste plastic soot coatings

316L grade stainless steel is widely utilized in industrial applications owing to its exceptional corrosion resistance. However, it is less resistant to aggressive marine environments that contain salt-based seawater. In the present study, we report effective anti-corrosive epoxy polymer coating engineered with carbon soot nanoparticles (derived from waste polyolefin plastics) and coated on a 316L steel substrate via controlled pneumatic fluid atomization technique. Morphological analysis of derived carbon soot nanoparticles revealed an average diameter to be in the range of 41–62 nm. Corrosion inhibition performance of the coatings was studied under aggressive chlorine-based environments via polarization plots, i.e., Tafel plots, and by natural salt spray test for the total duration of 20 days. The scratch test and the solvent resistance rub test revealed adherence to the developed coatings with a 316L steel surface. The developed coatings were found to be uniform, crack-free, and well bonded with the surface of steel substrates. Successive experimental results of the developed coatings indicated enhanced corrosion inhibition properties, which imply its practical applicability for under-water marine applications.

Effect of Si/O doping on the thermal stability of non-bonded hydrogenated diamondlike carbon coatings

Diamond-like carbon coatings containing Si and O (a-C:H:SiOx) were deposited onto 316L steel and silicon wafer substrates using a mixture precursor of hexamethyldisiloxane (HMDSO) and acetylene under a high bias voltage. Then, the coated coupons were annealed in an argon media. The hydrogen content in the coating was measured by 2 MeV 4He+ elastic recoil detection analysis (ERDA). The structure and morphology evolution during annealing were characterized by scanning electron microscopy (SEM), mass spectrometry (MS), Fourier transformation infrared spectroscopy (FTIR), Raman spectra, and X-ray photoelectron spectroscopy (XPS). The mechanical properties were investigated using a residual stress tester and nanoindentor. The results showed that under a high bias voltage a large amount of the hydrogen of the a-C:H:SiOx coatings did not bond with carbon. Si and O preferred to form SiC bonds and SiO bonds respectively to enhance C sp3 fraction, relax the residual stress, and depress the graphite cluster growth. During annealing, combining with C sp3 rehybridization, the transformation of the SiC bond to SiO or Si-C-O bonds caused hardness and residual stress variation. The a-C:H:SiOx coatings still held more than 12 GPa hardness after annealing at 590 °C for 4 h, while the hardness was approximately 8 GPa for the pure a-C:H coating.

Synthesis and high-temperature corrosion resistance of Ti-Zr-Si-N coatings deposited by means of sputtering

ABSTRACTWe present a study of the synthesis and an evaluation of the corrosion resistance of Ti-Zr-Si-N coatings deposited by means of the co-sputtering technique on 316L steel and Ti6Al4V alloy substrates. The thin films were obtained using Ti5Si2 and Zr targets with 99.9% purity for the deposition, and a power of 200 W was applied in the DC source and 170 W in the RF source. The corrosion resistance was evaluated via the cyclic oxidation test with consistent cycles of 1 hour of cooling, 1 hour of heating, and 16 minutes of stabilisation for 300 cycles at a temperature of 600°. The coatings were characterised by means of scanning electron microscopy (SEM), X-ray diffraction (XRD), and confocal laser microscopy. The coating was effective up to 150 cycles for the case of 316L steel, and up to 50 cycles for the Ti6AlV alloy.

Modification of 316L Steel Surface in Ozone Atmosphere

Abstract The study reported in this paper was undertaken to assess whether certain ecologically-disastrous surface treatments, such as chemical and electrochemical treatment could be replaced with ozonation. The proposed technology is both ecologically-sound and relatively inexpensive. The research works were conducted on 316L steel substrates and involved photoelectron spectroscopy (XPS). The band positions on the review spectrum provide the basis for the qualitative identification of the atoms forming the surface layer, whereas their intensity – data for the calculation of the total concentration of these atoms in the analysed layer. High resolution spectra are used to determine the type of chemical bonds – based on the characteristic numbers of chemical shift. The results of tests on the state of surface layer energy of 316L steel substrate following ozone treatment are also presented. The conducted tests and the analysis of the obtained results indicate that ozone treatment effectively removes atmospheric carbon contaminants off the specimen surface. The test results show a decrease in atmospheric carbon on samples after ozone treatment compared to untreated samples. Moreover, results show an increase in the value of the free surface energy in specimens subjected to ozone treatment.