Stainless Steel AISI Research Articles

Microstructure and tribological properties of multilayered ZrCrW(C)N coatings fabricated by cathodic vacuum-arc deposition

In this study, a series of ZrCrW(C)N multilayer coatings with various transition layers were deposited on AISI304 stainless steel using cathodic vacuum-arc deposition in N2–C2H2 gas mixture. The tribological behaviors of sliding against Al2O3 balls under dry friction and lubricant conditions were investigated using a reciprocating tribometer. The results demonstrated that the ZrCrW(C)N coatings comprised (Zr, Cr, W) (C, N) crystallites and an amorphous carbon phase. It possessed a nano-hardness of 35.4 GPa and an elastic modulus of 417.7 GPa. The friction coefficient of the coating was reduced by 14% compared to that of the 304 matrices, and the wear mechanism changed from adhesive wear to slight abrasive wear under the lubrication steady state. Under dry friction conditions, the ZrCrW(C)N coatings with the entire CrWN transition layer exhibited wear rates of 1.27 ± 0.04 × 10−8 mm3 (N m)−1, which were one order of magnitude lower than that of the 304 steel. Compared with the untreated AISI304 stainless steel, the ZrCrW(C)N coating exhibits excellent mechanical and tribological properties under lubricated and dry friction conditions, which are crucial for engineering applications.

Electrosynthesis of polyindole-carboxylic acids on stainless steel and their corrosion protection at different temperatures in acidic solution

Poly (indole-5-carboxylic acid) (5-PICA), Poly (indole-6-carboxylic acid) (6-PICA), and Poly (indole-7-carboxylic acid) (7-PICA) were electrowinning onto AISI304 stainless steel by cyclic voltammetry. They were characterized structurally and morphologically by IR spectroscopy and scanning electron microscopy (SEM). In addition, the study about corrosion protection was carried out using linear scanning voltammetry (LSV) and electrochemical impedance spectroscopy (EIS) in 0.5 mol·L−1 H2SO4 at temperatures of 20 °C and 45 °C. The results showed a close relationship between the morphology of the polymer and the carboxylic group (COOH) position, which also presented a spatial arrangement according to its branching. Furthermore, it directly modified its hydrophobicity, influencing the anticorrosive protection of AISI304 stainless steel. It provides a corrosion potential between 0.198 and 0.402 V, which is more positive than unprotected steel. Finally, the study revealed better protection at low temperatures, decreasing at 45 °C.

Characterization of the microstructure and mechanical properties of activated tungsten inert gas welded and hot-wire tungsten inert gas welded super austenitic stainless steel AISI 904L

Super austenitic stainless steel AISI 904L is a premium stainless steel variant known for its superior properties and ability to retain the same in highly challenging conditions. This study investigates the feasibility of welding 10-mm thick plates of AISI 904L through activated tungsten inert gas welding and hot-wire tungsten inert gas welding methods. The fabricated joints are then subjected to solidification mode study, ferrite number analysis, microstructural characterization, and mechanical tests. Results of the solidification mode study indicated primary austenitic solidification in both the weld joints. The ferrite number measurement revealed that the hot-wire tungsten inert gas weld joint had a higher δ-ferrite content of 1.58 over 0.99 of the activated tungsten inert gas weld joint. A microstructure study confirmed the presence of refined equiaxed grains in the fusion zone of the hot-wire tungsten inert gas weld joint, while the activated tungsten inert gas weld joint displayed equiaxed grains crammed between the columnar grains and dendrites. Liquid penetrant inspection of bend-tested samples proved the soundness and quality of both weld joints. The hot-wire tungsten inert gas weld joint excelled over the activated tungsten inert gas weld joint with a higher microhardness value. During tensile tests, activated tungsten inert gas and hot-wire tungsten inert gas weld joints displayed average ultimate tensile strength values of 521 and 514 MPa, respectively. The impact toughness of the activated tungsten inert gas weld joint was 248 J, while it was 220 J for the hot-wire tungsten inert gas weld joint. Field emission scanning electron microscope analysis equipped with energy-dispersive spectroscopy and elemental color mapping provided details about weld microstructure and the reasons for the material's failure. The study proved the efficiency and soundness of the 10-mm thick joints of AISI 904L fabricated by activated tungsten inert gas and hot-wire tungsten inert gas welding techniques.

Tribological behaviour of TiB2 ceramic based composite coating deposited on stainless steel AISI 304 by gas tungsten arc (GTA) cladding process

In this study, Titanium (Ti)-Titanium diboride (TiB2) metal matrix composite (MMC) cladding layers were fabricated on an AISI 304 stainless steel substrate by the gas tungsten arc (GTA) cladding process. The composite cladding layer was produced using different powder mixtures: 85 wt% TiB2−15 wt% Ti, 75 wt% TiB2−25 wt% Ti, and 65 wt% TiB2 −35 wt% Ti. During cladding, the GTA process currents were used in the range of 70 A to 90 A with 10 A interval differences and the scan speed in the range of 1.1 mm sec−1 to 1.9 mm s−1 with 0.4 mm s−1 interval differences. All samples were investigated for mechanical properties, microstructure, and phase analysis by Vickers microhardness, scanning electron microscopy (SEM), Energy dispersive x-ray spectroscopy (EDX), and x-ray diffraction (XRD) respectively. The x-ray diffraction (XRD) findings indicate that the composite coatings consist of TiB2, TiB, Ti, Fe3C, B4C, and NiTi phases. The presence of elements B, C, Ti, Cr, Mn, Fe, and Ni in the coating was confirmed by x-ray energy dispersive spectroscopy (EDX). The maximum microhardness value of the composite coating was enhanced in the range of 1639 HV0.1 to 3781 HV0.1, whereas the microhardness of the AISI 304 stainless steel substrate was 194 HV0.1. The average wear rate of the coated samples was determined in the range of 11.09 × 10−9 g N−1-m−1 to 27.63 × 10−9 g N−1m−1, whereas the average wear rate of the AISI 304 steel substrate was 88.414 × 10−9 g N−1m−1. It can be concluded that the maximum micro-hardness of the composite coating increased by 9-19 times than that of the nominal substrate (AISI 304 stainless steel). Also, the wear resistance of the composite coating enhanced by 8 times as compared to AISI 304 steel substrate. It is demonstrated in this study that the processing current, TiB2 content, and scanning speed have significant effect on the microstructure, mechanical, and tribological features of the cladding layers under consideration.

Development of a basic technology for multilayer electron beam cladding of Inconel 718 nickel-based alloy onto an austenitic stainless steel

Within the scope of the investigations, experiments were performed for single-bead and flat overlapping wire-based electron beam cladding (EBC) of the nickel-based alloy Inconel 718 onto the austenitic stainless steel AISI 347. The focus was on the influence of process parameters such as the wire feed rate, wire feed direction, electron beam energy input and the degree of overlap on the formation of the cladding layer in terms of microstructure, geometry, hardness and chemical composition, as well as the number of defects occurring. As a result, a suitable parameter set was identified for multilayer, defect-free cladding.

Failure Analysis of a Welded AISI321 Steel Bleed Air Connector of an Aircraft Engine

Failure investigation was conducted on a bleed air connector of an aircraft engine that developed an opening during service. The connector was a fabricated tubular structure wherein the flanges were circumferentially welded to a bent pipe on both the ends. The flanges and the pipe were made of austenitic stainless steel AISI 321. Fractography study confirmed that the connector had failed by fatigue mechanism. Fatigue crack had initiated at one of the weld joints. The exact location of the crack initiation was at the weld-to-tube interface. After initiation, the crack had propagated into the pipe resulting in loss of material by fracture. Investigation revealed that the primary cause of fatigue crack initiation in the connector was stress concentration at the weld joint resulting from improper weld joint design. Inferior quality of weld was another factor that contributed to the failure. A detailed analysis of the failure is presented in this article and remedial measures suggested for preventing recurrence of similar failures.

Growth and biofilm formation of Cupriavidus metallidurans CH34 on different metallic and polymeric materials used in spaceflight applications

Bacteria biofilm formation and its complications are of special concern in isolated structures, such as offshore stations, manned submarines and space habitats, as maintenance and technical support are poorly accessible due to costs and/or logistical challenges. In addition, considering that future exploration missions are planned to adventure farther and longer in space, unlocking biofilm formation mechanisms and developing new antifouling solutions are key goals in order to ensure spacecraft’s efficiency, crew’s safety and mission success. In this work, we explored the interactions between Cupriavidus metallidurans, a prevalently identified contaminant onboard the International Space Station, and aerospace grade materials such as the titanium alloy TiAl6V4, the stainless steel AISI 316 (SS316) and Polytetrafluoroethylene (PTFE) or Teflon. Borosilicate glass was used as a control and all surfaces were investigated at two different pH values (5.0 and 7.0). Biofilms were almost absent on stainless steel and the titanium alloy contrary to Teflon and glass that were covered by an extensive biofilm formed via monolayers of scattered matrix-free cells and complex multilayered clusters or communities. Filamentous extracellular DNA structures were observed specifically in the complex multilayered clusters adherent to Teflon, indicating that the employed attachment machinery might depend on the physicochemical characteristics of the surface.

Influence of annealing temperature on corrosion inhibition and nanostructure of nitride Ni and Ni/Ti coatings on AISI stainless steel

Influence of annealing temperature on corrosion inhibition and nanostructure of nitride Ni and Ni/Ti coatings on AISI stainless steel

Experimental study of the effect of oxygen in argon as a shielding gas on corrosion behaviour of dissimilar weld joints of austenitic and ferritic stainless steels

In this study, Austenitic AISI 304L stainless steel was welded with Ferritic AISI430 stainless steel by MIG–welding using welding electrode ER347 and pure Ar and Ar+2%O2 as the shielding gases. The welded samples were polished and dipped into different concentration of HCL solutions of 0.1M, 0.2M, 0.3M and 0.5M concentrations. Weight change of the samples per week in different concentration of HCL solution was noted for 4 weeks and with the help of weight loss, corrosion rate was calculated. The percentage weight loss was observed to be more when welding was done using pure-Ar as a shielding gas compared to Ar+2%O2. Welded samples were also characterized by means of microscopic and electrochemical investigation.

Optimization of Welding Parameters of AISI 431 and AISI 1020 Joints Joined by Friction Welding Using Taguchi Method

Martensitic stainless steel AISI 431 and low carbon steel AISI 1020 are materials used together in many different industries. However, important problems are encountered when welding (fusion welding) these materials to each other. For this reason, friction welding process (Solid-state welding) is used to join these dissimilar metals. There are very few studies on joining these materials with friction welding. Therefore, the optimization of the welding parameters used in joining these dissimilar steel pairs with friction welding is of great important. In addition, the effects of the factors dependent on friction welding parameters need to be well understood. In this study, AISI 431 and AISI 1020 steel bars were successfully joined by friction welding, and the effects of welding parameters on tensile strength and axial shortening were investigated, and welding parameters were optimized using Taguchi method to obtain quality weld joints. The experimental results of the study showed that the highest tensile strength (573.32 MPa) of the joints was 54.53%, higher than the lowest tensile strength (370.99 MPa), the highest axial shortening (23.18 mm) was 650.16%, higher than the lowest axial shortening (3.09 mm). The optimal parameters for average axial shortening and average tensile strength were determined as A3B1C3 and A3B3C2; and the highest percentage contribution values for axial shortening and tensile strength were found to be 51.55% (rotating speed) and 63.90% (rotating speed); and R2 values for the average axial shortening and average tensile strengths were found to be 97% and 99.3%, respectively.

Influence of Laser Marking on Microstructure and Corrosion Performance of Martensitic Stainless Steel Surfaces for Biomedical Applications

Abstract The medical device industry demands unique device identification (UDI) tags on metallic components applied via laser marking. A common issue is that the visual appearance of the marking becomes poorly legible over time due to loss of contrast. Nanosecond pulsed laser irradiation was used to grow an oxide layer on two different martensitic stainless steels AISI 420F mod and 420B to compare the influences of the chemical composition of the steel (with and without S), power density, and energy input. The corrosion behavior was found to depend strongly on laser energy input. The presence of sulfur negatively affected the corrosion resistance and narrowed the applicable window for the laser processing parameters significantly. For the sulfur-containing AISI 420F steel, 3‒5 μm wide craters formed on the surface after laser marking, which is interpreted as thermal degradation of protruding MnS inclusions resulting from the laser marking process. Also, substantial cracking in the oxide layer was observed. The marked specimens suffered from corrosion in a thin zone below the formed oxide layer. This behavior is attributed to Cr-depletion in the zone adjacent to the oxide layer, resulting from providing Cr to the growing oxide layer.

Электроискровое осаждение порошка диборида хрома на нержавеющую сталь AISI 304

Introduction. Austenitic stainless steel AISI 304 is the most widely used type of stainless steel. However, it is subject to wear due to relatively low hardness, and also begins to oxidize intensively in air at a temperature above 800 °C. The use of coatings based on chromium boride can improve its tribotechnical properties and oxidation resistance. The purpose of the work: to study the effect of chromium diboride concentration in the anode mixture on the structure, wear behavior, oxidation resistance and corrosion properties of electric spark coatings on AISI 304 steel. The research methods. Electric spark treatment of AISI 304 steel was carried out in a mixture of iron granules with the addition of CrB2 powder in amount of 5, 10 and 15 vol.%. The structure of the coatings was studied by X-ray analysis, scanning electron microscopy, and electron dispersion spectroscopy analysis. The wear resistance of the coatings was studied under dry friction condition at a load of 10 N. The oxidation resistance test was carried out at a temperature of 900 °C for 100 hours. Results and Discussion. According to X-ray analysis, it is shown that under the conditions of electric spark exposure, CrB2 interacts with iron melt; this has resulted in the formation of chromium and iron borides. Corrosion properties, microhardness, coefficient of friction and wear are investigated in comparison with AISI 304 steel. Samples with coatings showed a lower corrosion potential and corrosion current density compared to the substrate in 3.5% NaCl solution and from 5 to 15 times higher oxidation resistance. The microhardness of the coatings increased from 6.25 to 7.60 GPa with an increase in the addition of chromium diboride in the electrode mixture. The coefficient of friction and the wear rate of all coatings were lower than that of AISI 304 stainless steel, while the coating prepared with the addition of 5 vol.% chromium diboride had the best tribotechnical characteristics.

Corrosion studies and thermogravimetric analysis performed on activated tungsten inert gas and hot wire tungsten inert gas welded super austenitic stainless steel AISI 904L

Attributed to the remarkable resistance offered against various types of corrosion, AISI 904L is used for a wide range of challenging applications. In this context, this research aims to conduct an in-depth corrosion study about the base material and weldments of 10 mm thick AISI 904L plates fabricated by autogenous activated tungsten inert gas (ATIG) welding and hot wire tungsten inert gas (HWTIG) welding techniques. The pitting resistance effective number (PREN) is analyzed to evaluate pitting corrosion resistance. The Tafel plot is drawn and evaluated for the electrochemical corrosion of base metal and weldments in a 3.5% NaCl solution, while the specimens immersed in 3.5% NaCl solution at 650oC for 24 hours are evaluated for hot corrosion behavior. Thermogravimetric analysis (TGA) is performed at 300C–9000C to study material behavior at elevated temperatures. Results indicate that the base metal, ATIG weldment, and HWTIG weldment have a PREN of 34. During Tafel plot analysis, the ATIG weldment displayed a corrosion rate of 0.02792 mm/year while the HWTIG weldment recorded 0.02091 mm/year. Corrosion rates of ATIG and HWTIG weldments during hot corrosion studies are 14.93 mm/year and 12.69 mm/year, respectively. During TGA analysis, the ATIG weldment suffered a weight loss of 12.42% while the HWTIG weldment lost only 9.68% of its weight during the process. FESEM + EDS analysis confirmed the presence of unmixed flux particles in the ATIG weldment, which could be attributed to the weldment’s poor performance. In general, this research cemented the supremacy of the HWTIG weldment over the ATIG weldment with improved corrosion resistance and thermal stability. This study also contributed to a better understanding of the corrosion behavior of AISI 904L weldments under different environments that this superior grade of stainless steel alloy may encounter during its real-life applications.

The impact of synthetic musk compounds in biofilms from drinking water bacteria

Musk fragrances have been detected in drinking water (DW) at trace concentrations. However, their impact on the microbial quality of DW has been disregarded. This work provides a pioneer evaluation of the effects of two synthetic musks contaminants, tonalide (AHTN) and galaxolide (HHCB), in microbial biofilms formed on two different surfaces, polyvinyl chloride (PVC) and stainless steel AISI 316 (SS316). Three bacterial species isolated from DW (Acinetobacter calcoaceticus, Burkholderia cepacia and Stenotrophomonas maltophilia), were used to develop 7-day-old single and mixed species biofilms. The impact of musks was assessed directly on biofilms but also on the bacteria motility, biofilm formation ability and biofilm susceptibility to chlorination. AHTN musk caused the most remarkable effects by increasing the cellular density and viability of mixed biofilms, and the extracellular polysaccharides content of biofilms on SS316. Most of the alterations caused by the direct exposure of biofilms to musks were observed when SS316 was used as an adhesion surface. In contrast, the ability to form biofilms and their susceptibility to chlorine were more affected for bacteria from HHCB-exposed biofilms on PVC. The overall results demonstrate that the presence of musks at residual concentrations influences DW bacterial dynamics, with the potential to impact the DW quality and safety. The type of plumbing material may further impact the effects of musks.

Long crack propagation and closure in DC(T) specimens of Ni-based superalloy Inconel 718 and stainless steel AISI 301 after shot peening

In this study, the effects of severe shot peening on ambient temperature long crack growth, threshold and closure behavior in Nickel-based superalloy Inconel 718 and stainless steel AISI 301 were investigated. To assess the relationship between shot peening, crack tip shielding and crack growth, pre-cracked disk-shaped compact tension (DC(T)) specimens were treated at distinct locations around and ahead of the crack front. A beneficial influence of shot peening on crack propagation and closure was only identified in Inconel 718, albeit limited to shot peening of the entire area around the crack front. In contrast, the applied shot peening treatments had detrimental effects on crack growth properties in AISI 301. While the effective threshold of Inconel 718 was not affected by shot peening, AISI 301 featured a decreased intrinsic resistance against the onset of crack propagation. Strain-induced near-surface α′-martensite formed due to shot peening of AISI 301 was found to promote martensite formation during crack growth, giving rise to embrittlement of the material.

A study on formation mechanism of friction-surfaced stainless steel coating via a stop-action method

The formation mechanism of a friction-surfaced (FSed) coating of super austenitic stainless steel AISI 904 L with high stacking fault energy was investigated with a stop-action method. The advancing side, center and retreating side of the surfaces and cross-sections of the coating and the bump were studied in detail using EBSD. The microstructure of the bump formed at the end was found to be different from that of the FSed coating. A systematic analysis of the microstructure revealed the formation mechanism of the coatings. A two-step formation mechanism of the FSed coating was proposed.

Parameter optimization and experimental validation of A-TIG welding of super austenitic stainless steel AISI 904L using response surface methodology

Super austenitic stainless steel (SASS) is a premium stainless steel (SS) variant which finds applications in challenging environments. One of the premium grades of SS that falls under the said category is AISI 904L. Autogenous activated flux tungsten inert gas (A-TIG) welding is an established technique for fabricating sound steel joints which offers various advantages. In this context, this research aims to identify an optimum set of input process parameters to effectively employ A-TIG welding to fabricate 10 mm thick joints of SASS AISI 904L plates by employing bead on plate welding trials. The input parameters varied for the trials are welding current, torch travel speed, and percentage of Argon gas present in a mixture of Argon and Helium – which is the shielding gas used, while the responses were the depth of weld penetration (DOP) and weld bead width (BW). For finalizing the combinations of input parameters and the run order of the welding trials, the design of experiments (DOE) was performed using central composite design (CCD) of response surface methodology (RSM). After performing the trials, the DOP and BW attained were measured and the data thus generated were analyzed to study the influence of varying input parameters on the two responses. Analysis of variance (ANOVA) was then performed to check the input parameter's level of significance. RSM's desirability approach was used for numerical optimization to attain maximum DOP and a moderate BW. A linear regression equation generated can be used to precisely predict DOP and BW for any random values of input parameters. The bead on plate trial's validation study displayed root mean squared error (RMSE) values of 0.328 and 0.653 for DOP and BW respectively, The RMSE values of DOP and BW of the joint fabricated with optimized parameters was 0 and 0.311 respectively.

Analysis By Taguchi and ANOVA Methods For The Effect Of The Cutting Tool Height Adjustment On Cutting Forces In Turning AISI304 Stainless Steel Material

Analysis By Taguchi and ANOVA Methods For The Effect Of The Cutting Tool Height Adjustment On Cutting Forces In Turning AISI304 Stainless Steel Material

Wear of Bulk Metallic Glass Alloys for Space Mechanism Applications

Abstract Space-based mechanisms must operate under harsh environments, usually without access for maintenance; failure may result in a loss of a spacecraft. Therefore, space agencies support research on high-performance mechanism designs and materials, one key area being space tribology. Bulk metallic glasses (BMGs) are a class of alloy characterized by their amorphous structure, which results in a material with extremely high strength, corrosion resistance, high hardness, and high elastic limit. BMGs have demonstrated improved wear resistance when compared against traditional engineering materials in similar applications. Four BMG compositions, Zr53Al16Co23.25Ag7.75, Zr49Ti1.96Cu37.24Al9.8Y2, Zr60Ti2Nb2Al7.5Ni10Cu18.5, and Cu47Zr46Al5Y2 (at%), were selected from the literature as potential candidates for space-based mechanisms applications. Wear testing, hardness, profilometry, and scanning electron microscopy (SEM)/energy dispersive X-ray (EDX) spectroscopy analysis were performed on the selected alloys, and their results were compared. High-resolution 3D profilometry and detailed image analysis of wear tracks and volume loss resulted in a critical re-assessment of the Archard wear coefficient. For the compositions tested, the hardness was not a useful predictor of the wear performance as suggested by the Archard wear equation. Processing history and test configuration significantly influenced the wear behavior. The alloy Zr49Ti1.96Cu37.24Al9.8Y2 was found to be the best BMG candidate for space wear applications when taking manufacturability into consideration. BMG hardness and wear test results were compared with similar testing performed on conventional crystalline alloys commonly used in space applications: titanium alloy Ti-6Al-4V ELI, and cold-worked stainless steels AISI 303 and AISI 304.

Investigation on characteristics of tensile damage and microstructure evolution of steel AISI 316L by nonlinear ultrasonic Lamb wave

In view of the high sensitivity to microstructure evolution of higher harmonics generated by the nonlinear ultrasonic method, the tensile damage in the stainless steel AISI 316L was evaluated by nonlinear ultrasonic Lamb wave. The effect of different degree of tensile deformation on nonlinear ultrasonic response in 316L was analyzed by considering the microstructure evolution and the test results. First, the power-law relation of nonlinear ultrasonic parameter and plastic strain is proposed. Meanwhile, martensitic transformation and the increasing of dislocation density can be observed in the micrographs of specimens with the increase of plastic deformation. Then, the same variation tendency of intergranularly averaged Kernel Average Misorientation (KAM), as well as the relative nonlinear ultrasonic parameter, demonstrated that the nonlinearity due to tensile damage is controlled by the evolution of microstructure that directly affects higher order elastic constant of stainless steel 316L. Furthermore, based on continuous damage mechanics, the method quantitatively characterizes the degradation of mechanical properties was proposed with a functional relation of damage variable and relative nonlinear parameter. The method proposed in this study provides a theoretical basis for online monitoring of the damage status of in-service equipment. It is of great significance for residual life assessment, structure integrity assessment, and service life extension of equipment.