Stainless Steel AISI Research Articles

Microstructural evaluation in dissimilar liquid phase bonding of cast Al–Si alloy and stainless steel using pure zinc filler metal

The metallurgical joining between cast A359 aluminium alloy and AISI321 stainless steel using pure Zn as the interlayer was performed slightly above Al–Zn eutectic temperature. The liquid phase was formed by a eutectic reaction between Al and Zn and subsequently isothermally solidified by diffusion of Zn into the A359 base metal (i.e. reactive transient liquid phase bonding). The formation of a Zn-rich diffusion affected zone in A359, incorporation of Si particles into the bond zone, formation of a thin Al–Fe–Si intermetallic at the steel interface, and isothermal solidification of the liquid phase and subsequent Al–Zn eutectoid transformation govern the microstructure of the joint. The resultant bond microstructure does not deleteriously affect the heat sink function of Al base metal.

Region-wise evaluation of strength and creep behavior of AISI 904L weldments by small specimen testing techniques

Super austenitic stainless steel AISI 904L is a premium stainless steel renowned for its outstanding characteristics and the ability to be maintained even under harsh situations. This alloy is widely used in a variety of engineering applications, and hence generating creep and indentation data of the material will prove useful for those concerned. Our study investigates the impression creep (IC) and automated ball indentation (ABI) performance in activated tungsten inert gas (ATIG) and hot wire tungsten inert gas (HWTIG) weldments of 10 mm thick plates of AISI 904L. ABI-evaluated strength correlates well with the conventional uniaxial tensile test and hardness data. IC studies were performed on base metal and welds by applying a load of 60 kg on a 1 mm diameter flat-end cylindrical punch at 650 oC. Several cycles of loading followed by partial unloading were performed on ABI specimens at 25 °C using a 0.76 mm diameter tungsten carbide spherical indenter. The results indicated that the ATIG weld excelled over the HWTIG weld with higher creep resistance. During the ABI analysis, the heat-affected zone of HWTIG weldment displayed higher UTS and ABI hardness values of 499 MPa and 185 HB, respectively. Hardness values generated by the ABI analysis are 174 HB, 161 HB, and 177 HB for the base metal, ATIG weldment, and HWTIG weldment, respectively. This was found to be very much in agreement with conventional hardness test results. The results cemented the ability of IC and ABI analysis to precisely predict the creep and mechanical properties of the base metal and weldments. Data generated through this study will benefit industries and researchers associated with AISI 904L.

Laser micro-welding of stainless steel foil: Welding mode, microstructure and corrosion properties

Laser micro-welding differs from macro-welding in that at least one dimension of the weld is less than 100 μm. Although process research on laser micro-welding has recently made some progress, the influence of welding mode on microstructure and corrosion resistance has remained unknown, which has been shown to have a significant influence on laser macro-welding. In this work, a single-mode fiber laser equipped with a scanning galvanometer is used to weld AISI304 stainless steel foils with a thickness of 100 μm. Similar to laser macro-welding, keyhole formation is used to describe two welding modes, namely thermal conduction welding and penetration welding. The laser-material interaction experiences a transient phase in which the welding mode alternates between conduction welding and penetration welding as reported by previous work. However, we show that gas protection eliminates the transient phase, proving that the transient phase develops as a result of the unsteadiness of the penetration welding caused by oxidation during the welding process. The crystallographic texture and phase constitution vary between conduction and penetration welds due to variations in heat transfer behavior during welding. The conduction weld has greater Σ3 CSL boundaries and a more uniform microstructure than the penetration weld, resulting in better corrosion resistance.

TRIP effect produced by cold rolling of austenitic stainless steel AISI 316L

TRIP effect produced by cold rolling of austenitic stainless steel AISI 316L

Formation mechanism and oxidation behavior of Cu–Mn spinel coating on ferritic stainless steel for solid oxide fuel cell interconnects

Buckling damage and spallation during oxidation are prime challenges in electroplated Cu–Mn oxide spinel coatings prepared for SOFC interconnects. (Cu,Mn)3O4 spinel coating is formed on AISI-430 stainless steel by oxidizing electroplated copper and manganese layers at 750 °C in air. Nickel strike deposition significantly reduces coating spallation. During oxidation at 750 °C, spinel coating hinders chromium migration and improves the oxidation behavior of the alloy by a decrease of 98.9% in the parabolic oxidation rate constant. Formation mechanism of the spinel is investigated, revealing that manganese initially forms MnO, Mn2O3, and Mn3O4. Over the time, copper oxidizes to CuO, and Mn2O3 replaces MnO and Mn3O4. Finally, (Cu,Mn)3O4 spinel forms after 6 h of oxidation by the co-existence of CuO and Mn2O3. It is concluded that manganese oxidation induces buckling damage due to a volume increase of up to 137% in the coating during the earliest stages of the oxidation.

Joining Stainless-Steel AISI 304 and High-Strength Aluminum Alloy AA 6082 by Brazing Using Al-Ge-Si Foils

An Al-40.0Ge-3.4Si wt.% alloy foil with a thickness of 50 ± 5 μm, obtained via an ultrafast solidification method, is described in this work. A complete wetting of the aluminum alloy substrate with a wetting angle of 0° is observed, and the formation of a drop with a wetting angle of 30 ± 5° is observed on the steel substrate. Similar and dissimilar brazed joints of aluminum alloy AA 6082 and stainless-steel AISI 304 are obtained. The microstructure of the AA 6082/AA 6082 brazed seam is homogeneous and contains particles of an Al7Fe2Si system intermetallic compound and particles of an Al-Ge eutectic composition. The brazed seam of the AISI 304/AISI 304 joint is formed due to the formation of the Al8Fe2(Si, Cr) intermetallic compound reaction layer on the steel surface. The proposed scheme for the AISI 304/AA 6082 brazed joint formation is given. The brazed seam represents the Al8Fe2(Si, Cr) reaction layer on the steel surface, the thickness of which depends on the holding time during brazing, and the aluminum matrix of which has particles of a composition close to an Al-Ge eutectic. The obtained results could be used for the optimization of time–temperature brazing modes in order to improve the mechanical characteristics of AISI 304/AA 6082 dissimilar joints.

Parameters affecting the quality of friction drilled holes and formed thread in austenitic stainless steel AISI 304

The main purpose of this research paper is to improve the quality of the friction-drilled holes and formed thread by investigating the influence of the input working parameters that have not been investigated yet on the quality of the produced bores. Due to lack of research related to the hardness macro- and microstructure of formed threads, experiments were conducted to investigate these important issues. Finally, a tension test was performed to compare the performance of the form tapped thread with the conventionally cut thread. The experiments were conducted on difficult-to-cut material AISI 304 stainless steel workpieces with (2 and 3 mm) wall thicknesses. Tungsten carbide friction drills with diameters (Ø9.2, Ø7.3, and Ø4.5 mm) were used to perform the experiments. The effects of the ratio of workpiece thickness (t) to tool diameter (dT), rotational speed (N), and feed speed (f) on the hole diametral oversize (U), cylindricity error, and collar height were studied. The analysis of variance (ANOVA) showed that the t/d ratio was the most significant factor affecting the mean cylindricity error and the collar height. By comparing the performance of the three tools, it was noticeable that the friction drill Ø7.3 realized better results in terms of mean hole diametral oversize and mean cylindricity error. The elevated temperature associated with high plastic deformation during the processes resulting in fine grains with high hardness values were observed at the heat-affected zone. The longer effective thread length of the formed thread realized higher strength values than the cut thread.Graphical abstract

Performance of micro-beam X-ray absorption spectroscopy at beamline 7.2W of Synchrotron Light Research Institute

The existing BL7.2W beamline at SLRI, initially developed for Macromolecular Crystallography, was upgraded with a Si-drift X-ray detector, sample micro-stage, and polycapillary X-ray lens to provide possibilities for experiments using X-ray fluorescence (XRF) imaging and micro-beam X-ray absorption spectroscopy (μXAS) techniques. The micro X-ray beam was characterized. The beam diameter of approximately 25 μm was determined from the knife-edge scan method. The measured photon flux was 3.8 × 109, 1.8 × 109, and 6.4 × 108 photons/s for 8.0, 10.0, and 12.0 keV X-rays, respectively. Imaging XRF and μXAS measurements were successfully performed on a welding joint of oxygen-free high thermal conductivity copper and AISI304 stainless steel. This opens opportunities for SLRI users to utilize this new measurement setup for elemental and chemical characterizations of small areas on various samples.

Comparative corrosion study of HVOF coated Wc-10Co-4Cr, NiCrBSi and NiCr industrial waste coatings on AiSi304 stainless steel

The increasing demand for the high-velocity oxy-fuel (HVOF) thermal sprayed coated steel for boiler tube applications is the driving force behind this research work. Following the needs of the industry, the present study is aimed at understanding and comparing the corrosion resistance behavior of the WC-10Co-4Cr, NiCrBSi, and NiCrIW coating on AISI 304 stainless steel. A detailed microstructural characterization of the coatings before and after the corrosion experiment by FESEM, phase identification by XRD, and porosity determination by image analysis was performed. Corrosion behaviors of the coatings are examined by the electrochemical measurement technique after their immersion in a solution of 4 % NaCl for 1 hr, 12 hr, 36 hr, 102 hr, 200 hr, and 250 hr. Electrochemical impendence spectroscopy and Potentiodynamic polarization test results show that the porosity of the coatings and interface between unmelted particle and matrix (Formation of micro-galvanic cell) are potential sites for corrosion initiation. Electrochemical impedance spectroscopy (EIS) data indicates that the corrosion resistance of all types of coating initially decreases with increasing immersion time, but after some time corrosion resistance of the coatings again increases with increasing immersion time. This is because of the local accumulation of corrosion products in the defects hindering penetration of the electrolyte easily. Both the corrosion studies revealed that corrosion resistance of the coatings is in the following order: NiCrBSi > WC-10Co-4Cr > NiCrIW.

A review on minimum quantity lubrication for sustainable machining of titanium alloy

In the pursuit of sustainable manufacturing, both academics and industries have been facing numerous challenges. The same has been the case in the specific domain of machining. The many applications for cutting fluids for lubrication & cooling purposes have been found as the most dominant contributor when performing both sustainability and cost assessments. The past few decades witnessed the emergence of MQL (Minimum Quantity Lubrication) as a highly beneficial technique however there exists a vast potential in the further improvisation of the traditional MQL techniques that most researchers focused upon. One such alternative improvement is the use of nanofluids instead of virgin oils (synthetic or organic) such techniques have resulted in reported improvements in thermal conductivity, viscosity, wettability, etc. of the coolant. The study shall focus on enlightening the advantages and impacts of using nanofluids while cutting three difficult-to-cut machine materials namely AISI Stainless Steel, Inconel, and Titanium, and compare the result with the traditionally used MQL as well as the other commonly used cooling strategies. The knowledge of such variations in results in terms of output parameters was surface roughness, tool wear, chip morphology, thrust force, torque, etc. shall exist further research studies deciding the working parameters and eventually moving well aligned with the sustainable manufacturing.

HIGH-TEMPERATURE PASSIVATION OF THE SURFACE OF CANDIDATE MATERIALS FOR LSR BY ADDING O<sup>2–</sup> TO THE SALT PHASE OF THE HALIDE MELT

Experiments were carried out to determine the corrosion rate of stainless steel AISI 316 in a fluoride melt with different concentrations of O2– (by adding lithium oxide to the melt in the concentration range from 0 to 5 wt %). The corrosion rate decreases by an order of magnitude at an oxygen anion concentration in the melt from 0.2 to 0.4 wt %, which may indicate the detection of the phenomenon of high-temperature passivation of the material due to the modification of the composition of the fluoride melt and a decrease in its corrosion activity. In addition, the type of intergranular and pitting corrosion typical of stainless steels in fluoride melts, which is the most dangerous from the point of view of the structural reactor material, changes to continuous when lithium oxide is added due to the “healing” of individual corrosion centers with excess oxygen-containing compounds. The formation of a protective layer of the spinel type with a thickness of 1 μm was established.

Tensile And Formability Studies on AISI310 Austenitic Stainless Steel

Stainless steel is an alloy of iron, chromium, and, occasionally, nickel and other metals that resists corrosion. Metal is made into thin, flat pieces through an industrial process called sheet metal. One of the fundamental shapes used in metalworking, it can be cut and bent into many other shapes. Metal sheet is used to create a vast array of common items. The aim of the current work is to examine the 310 austenitic stainless steel’s formability at room temperature with different strain rates (i.e 0.1&0.01mm/s). The study’s outcomes were achieved through the utilization of the Nakazima test during stretch forming. Before performing formability test, The mechanical properties of a high-strength stainless steel AISI 310 were examined by conducting tensile tests at room temperature with 0.1,0.01mm/s strain rates. The failure modes, stress-strain curves of all the test specimens were obtained and analyzed. In the current experiment, the stretch forming of different shaped metal was tested in servo electric hot forming machine with different strain rates i.e, (0.1,0.01) at room temperature and plotted forming limit diagrams based on the results. Then simulations of the experiments were performed in LS-dyna software and compared with the practical experiment results.

Experimental Formability and Finite Element Studies on AISI310 Austenitic Stainless Steel

Stainless steel, an alloy comprising chromium, iron and occasionally nickel and other metals, demonstrates exceptional corrosion resistance. The transformation of metal into thin, flat components is achieved through the industrial process known as sheet metal fabrication. The utilization of metal sheets is widespread, contributing to the creation of numerous everyday items. This study aims to investigate the formability of 310 austenitic stainless steel under varying temperatures (623K, 723K, and 823K). The evaluation was executed utilizing the Nakazima test method within the context of the stretch forming procedure. Prior to delving into the assessment of formability, an exhaustive examination of the mechanical properties of the high-strength stainless steel AISI 310 was conducted. This involved subjecting the material to tensile tests at varying temperatures - specifically, 623K, 723K, and 823K - each performed at a consistent strain rate of 0.1/s. The resultant data encompassed an array of failure modes and stress-strain curves for the individual test specimens, all of which were meticulously obtained and subjected to thorough analysis.Forming limit diagrams were subsequently constructed based on the gleaned results, affording a visual representation of the material’s formability under the specific conditions studied. Moreover, these experiments were replicated through simulations employing the LS-DYNA software, with a subsequent comparative examination conducted against the tangible outcomes derived from practical experimentation.

Mechanical and Metallurgical Properties of Dissimilar Joining of 304 ASS: A Review

The mechanical and metallurgical properties of dissimilar joining of 304 stainless steel (SS) and other alloys have been extensively studied in recent years. Stainless steel is a widely used material in various industries such as aerospace, chemical processing and transportation. The austenitic Chromium-Nickel stainless steel AISI 304 provides the best balance of corrosion resistance, endurance, and ductility. Due to the low carbon content, carbide precipitation during welding is less likely. The dissimilar welding of AISI 304 austenitic stainless steel using various welding techniques with various materials was thoroughly reviewed in the current paper. According to the review, the optimum material to use when intergranular corrosion is a concern is AISI 304 austenitic stainless steel. It is also among the best materials usually utilised in the production of components that cannot be heated.

Comparison of crack growth rates of IPE beams made from stainless steel in three-point bending

The main focus of research dealing with a fatigue of steel components is mostly performed by mechanical testing with focus set on small-scale components. On the other hand, from a civil engineering viewpoint, the steel load-bearing structures or their elements have much larger dimension, when comparing them to laboratory specimens. Therefore, the fatigue testing took place on IPE 80 specimens made from two different stainless steels AISI 304 and AISI 316, loaded in three-point bending with data collection of crack mouth opening displacement placed in mid-span using clip-on extensometer. This presented study focuses on the comparison of crack propagation rate in linear region of well-known Paris’ law. For the assessment of material constants from Paris’ equation C and m, two steel grades of stainless steel, AISI 304 and AISI 316 were experimentally obtained. To evaluate the experimental data, a three-dimensional (3D) numerical model, representing IPE 80 geometry, in a finite element method (FEM) software Ansys Mechanical APDL was created. The generated numerical results were used to evaluate stress intensity factor values, which serves as a main input to crack propagation Paris’ law.

CAVITATION EROSION RESISTANCE OF HIGH-ALLOYED Fe-BASED WELD HARDFACINGS DEPOSITED VIA SMAW METHOD

In order to investigate the cavitation erosion (CE) resistance of high-alloyed ferrous hardfacings, the three different deposits were pad welded by the shielded metal arc welding (SMAW) method. Consumable electrodes differed in the content of carbide-forming elements, and pad welds were deposited onto the S235JR structural. The CE tests, conducted according to ASTM G32 standard, indicated that hardfacings reveal lower mass loss than the reference stainless steel AISI 304 (X5CrNi18-10). The hardfacings show increasing resistance to CE in the following order: Cr-C < Cr-C-Mo < Cr-C-Mo-V-W. The reference steel revealed more than twenty times higher material loss in the CE test than Cr-C-Mo-V-W hardfacing, which had outstanding hardness (825HV0.3). The profilometric measurements and scanning electron microscopy investigations showed large changes in valley and peak sizes of the roughness profiles for materials which displayed high erosion rates. The erosion mechanism of the coatings can be classified as brittle-ductile and relies on cracking, chunk removal of material, pits and craters formation, and deformation of fractured material tips and edges. Hardfacing materials failed primarily due to brittle fractures with different severities. Specimen surface degradation follows the changes in Ra, Rz, Rv, and Rp roughness parameters and well-corresponds to the proposed roughness rate (RR) parameter.

The isotropic and anisotropic self-cleaning surfaces by using only femtosecond laser

The current study describes a technique for surface modification that uses only femtosecond laser pulses that are extremely brief. The development in this research is the feature with periodically and directionally fabricated hierarchical micrometre scaled shapes with nanometer scaled structures. Although the developed features have complex structural makeup, they exhibit isotropic and anisotropic behaviour in superhydrophobicity. The developed Stainless Steel AISI 304 surface with appropriate modification using a femtosecond laser is the used method in this study. The recommended method may be applied to other vulnerable surfaces, including ceramic, polymers, semiconductors, and insulators as well as metals and alloys. The few functional fields that may use this method include self-cleaning surfaces, antibacterial surfaces, anticorrosion surfaces, anti-icing surfaces, and anti-biofouling surfaces. The Opto digital microscope with nanoscale resolution profoundly assisted us in finding developed features in its accuracy. We studied all of the featured topographies using sophisticated imaging tools. The presence of the preplanned features can also be demonstrated by field emission and tungsten filament scanning electron microscopy, and by atomic force microscopy. Studies on hydrophobicity carried out with Matlab assistance included a digital goniometer. Surfaces that are isotropic and directional with hydrophobic behaviour differed by water rolling on 0.5–3.5° tilted angles. All the manufactured superhydrophobic surfaces are reported to be above 155° and at most 167.13° is also a notable value. The results of the conical microspikes, which mimic a lotus leaf, show that they are exclusively hydrophobic isotropic at 0.5° of sliding angle. Biomimetic sinusoidal microgrooves in grass leaves reported remarkably directional or anisotropic hydrophobicity at a 2.5° rolling angle. So that we can elaborate on the use of femtosecond laser on hydrophobicity, we are reporting the results that have been proven to the appropriate fields. The ultrashort pulsed micromachining is used as the low waste machining technique's least time-consuming operation.

Continuous Wave Fibre Laser Welding of AISI Stainless Steel SS 410 and Mild Steel

The main aim of this paper is to study laser welding of AISI stainless steel (SS) 410 and mild steel (MS) at different values of welding power, welding speed and frequency. The welding of dissimilar metals is most useful in structural, automobiles, furniture and decorative applications. But there is a difficulty in welding of mild steel and stainless steel due to the loss of carbon from mild steel and precipitation of chromium in stainless steel. Laser welding is best suitable process which is used to control the problems occurred during welding on base metals joints. A 2 kW continuous wave fibre laser welding machine was used to weld 2 mm thick stainless steel (SS) and mild steel (MS) plates. The photos of the welded joints were assessed and then tested to investigate the mechanical properties of the welded joints.

Осаждение силицида титана на нержавеющую сталь AISI304

Introduction. Metal-ceramic coatings based on titanium silicide are promising for protecting stainless steel AISI 304 from wear, corrosion and high-temperature oxidation. Purpose of the work: to investigate the stainless steel AISI 304 surface layer structure after electrospark deposition in a mixture of titanium granules with silicon powder, and to study oxidation resistance, corrosion resistance and tribotechnical properties of the obtained coatings. Research methodology. Fe-Ti-Si coatings on the stainless steel AISI 304 samples were obtained by electrospark machining with a non-localized electrode consisting of titanium granules and 2.6-6 vol.% mixture of titanium and crystalline silicon powders. Results and discussion: it is shown that a stable positive gain of the cathode is observed when the proportion of silicon in the powder mixture does not exceed 32 vol.%. The phase composition of the coatings includes: a solid solution of chromium in iron, titanium silicide Ti5Si3, titanium and silicon, which is confirmed by the energy dispersion analysis data. The microhardness of Fe-Ti-Si coatings ranges from 10.05 to 12.86 GPa, which is 5-6 times higher than that of uncoated steel AISI 304. The coefficient of friction of the coatings is about 20% lower compared to steel AISI 304 and hovers around 0.71-0.73. Wear tests in dry sliding mode show that Fe-Ti-Si coatings can increase the wear resistance of steel AISI 304 up to 6 times. The oxidation resistance of the coatings at a temperature of 900 ̊С is 7-12 times higher as compared to steel AISI 304. The conducted studies have shown that new electrospark Fe-Ti-Si coatings can increase corrosion resistance, oxidation resistance, microhardness, as well as reduce the coefficient of friction and wear rate of the stainless steel AISI 304 surface.

High temperature degradation of AISI 304L stainless steel in atmospheres containing CO of biomass to liquid plants at 800 °C

Austenitic stainless steel (ASS) AISI 304L is required for the tube parts in biomass power plants due to high-temperature corrosion resistance properties. However, the high percentage of 35–40 % carbon monoxide and 25–35 % carbon dioxide in biomass atmospheres lead to deterioration in the ASS steels at high temperatures, resulting in chromium carbide formation and intergranular corrosion (IGC). This present work explored the degradation of the stainless steel AISI 304L in a simulated 15 %CO-N2 atmosphere at 800 °C at different testing times between 15 and 60 min. Besides, the ASS samples were pre-oxidized at 800 °C for six hours in air atmospheres before the test. Field emission scanning electron microscope (FE-SEM) and energy dispersive spectroscopy (EDS) were used for carbide characterization. The mass gain of samples was seemingly not changed after prolonging the reduction times. A double loop electrochemical potentiokinetic reactivation (dl-EPR) was used to observe the degree of sensitivity (%DOS) of AISI 304L samples. After the reduction test, the %DOS of samples exceeded the intergranular corrosion severity of 1 %, and the highest %DOS was 7.73 % after the reduction time of 45 min.