Stainless Steel AISI Research Articles

Study of the propagation of an intense ion beam to the target

The results of studying the intense ion beam propagation with peak energy up to 330 keV are presented. The ion beam was injected into the metal tube made from stainless steel in the form of a hollow cone. It was found that the ion beam focused due to neutralizing the space charge and reducing the divergence of ions. Neutralization of the beam space charge was investigated by measuring its electric potential. The average energy density of a beam increased up to 2.9 J/cm2 over the beam cross-section in the focal plane. The ion beam current density in the tube rose by a factor of 3 in comparison with geometric focusing. The analysis of the surface structure of the ion beam spot obtained on the stainless steel AISI 304 plate was done.

EXPERIMENTAL STUDY OF COOLING SPRAY METHOD ONTO INCLINED HEATED SURFACES

Single droplet impingement onto inclined heated surface is studied experimentally. Droplet in the form of aquades is dropped from a fixed height 70 mm to the metal surface with 45º impact angle. This experiment uses 3 types of metals; Stainless Steel AISI 304, Aluminum Alloy 2024, and Copper. All material surfaces are mirror polished and assumed to have the same surface treatment condition. Surface temperatures are 110 ºC, 150 ºC and 210 ºC to determine droplet behavior characteristics. The droplet has 3.0 mm diameter and 28.5 Weber Number (low impact category). In order to analyze droplet behavior in slow motion high velocity camera 4000 fps (frames per second) is used with image resolution 1024 x 768. Data obtained then processed using MATLAB image processing technique to analyze sequence of images visually and quantitatively to determine several parameters; spreading ratio, dimensionless height and contact time.The results showed droplets have different behavior characteristics even at the same surface temperature. Droplet contact time on the copper surface is shorter than aluminum and stainless steel. This is because droplets experienced bouncing due to film boiling regime takes place earlier. Maximum spreading ratio of stainless-steel surfaces is higher than copper because changes of boiling regime on stainless steel surfaces are slower and droplet is still experiencing spreading on the surface

Decomposition kinetics of expanded austenite with high nitrogen contents

Abstract This paper addresses the decomposition kinetics of synthesized homogeneous expanded austenite formed by gaseous nitriding of stainless steel AISI 304L and AISI 316L with nitrogen contents up to 38 at.% nitrogen. Isochronal annealing experiments were carried out in both inert (N2) and reducing (H2) atmospheres. Differential thermal analysis (DTA) and thermogravimetry were applied for identification of the decomposition reactions and X-ray diffraction analysis was applied for phase analysis. CrN precipitated upon annealing; the activation energies are 187 kJ/mol and 128 kJ/mol for AISI 316L and AISI 304L, respectively. Isothermal stability plots for expanded austenite developed from AISI 304L and AISI 316 were obtained.

Testing Laser-Structured Antimicrobial Surfaces Under Space Conditions: The Design of the ISS Experiment BIOFILMS

Maintaining crew health and safety are essential goals for long-term human missions to space. Attaining these goals requires the development of methods and materials for sustaining the crew’s health and safety. Paramount is microbiological monitoring and contamination reduction. Microbial biofilms are of special concern, because they can cause damage to spaceflight equipment and are difficult to eliminate due to their increased resistance to antibiotics and disinfectants. The introduction of antimicrobial surfaces for medical, pharmaceutical and industrial purposes has shown a unique potential for reducing and preventing biofilm formation. This article describes the development process of ESA’s BIOFILMS experiment, that will evaluate biofilm formation on various antimicrobial surfaces under spaceflight conditions. These surfaces will be composed of different metals with and without specified surface texture modifications. Staphylococcus capitis subsp. capitis, Cupriavidus metallidurans and Acinetobacter radioresistens are biofilm forming organisms that have been chosen as model organisms. The BIOFILMS experiment will study the biofilm formation potential of these organisms in microgravity on the International Space Station on inert surfaces (stainless steel AISI 304) as well as antimicrobial active copper (Cu) based metals that have undergone specific surface modification by Ultrashort Pulsed Direct Laser Interference Patterning (USP-DLIP). Data collected in 1 x g has shown that these surface modifications enhance the antimicrobial activity of Cu based metals. In the scope of this, the interaction between the surfaces and bacteria, which is highly determined by topography and surface chemistry, will be investigated. The data generated will be indispensable for the future selection of antimicrobial materials in support of human- and robotic-associated activities in space exploration.

Performance evaluation of TIG cladded in-situ TiC-TiB2 composite coating fabricated on AISI304 stainless steel

Tungsten inert gas (TIG) cladding is a surface modification technique used to deposit a coating with hard and resistance to wear material, which can improve the operational life of engineering components. In the present work, to improve the mechanical performance of AISI 304 stainless steel, in-situ TiC-TiB2 composite coating was fabricated through TIG cladding route by pre-placing Ti and B4C powder mixture at 3:1 wt ratio. The single line clad width and height was measured from the cross-sectional SEM images of the clad track. The microstructural analysis of the clad layer was accomplished through SEM images; however, EDS analysis was performed to study the distribution of different elements present in the clad layer. Almost a uniform clad layer with minor pores at the boundaries of the clad track was observed. The micro-hardness values variation towards the depth of the coating were evaluated for the clad layers deposited with different arc scanning speeds. Average value of micro-hardness was recorded between 800 and 1000 HV0.05, which was significantly higher than the substrate hardness.

Investigation on wire electrical discharge machining of AISI 304 stainless steel

This paper presents an experimental investigation of the machining characteristics of the AISI304 stainless steel in the wire electrical discharge machining (WEDM) process. During experiments, parameters such as peak current, pulse on time, pulse off time, wire feed, and wire tension are varied to explore their effects on the response variables such as material removal rate and surface roughness. All the experimental runs have been conducted using a brass wire electrode. Taguchi L16 orthogonal array has been selected for designing the experimentation, and the principal component analysis (PCA) method is used to optimize the responses parameter. This study found that pulse on time is the most crucial factor influencing machining characteristics. It was also revealed that peak current and pulse off time impact surface roughness.

Super-capacitive behaviour of polypyrrole thin film prepared by electrodeposition technique and characterization

The study conducted in this paper is on fabrication of thin poly-pyrrole film designed with an electro-deposition method on AISI304 stainless steel substrate. For enhancing super-capacitive characteristics of electrodes, a thin poly-pyrrole layer was deposited with an electro-deposition technique, following a potentiostatic method from an aqueous solution of pyrrole containing 5-sulfosalicylic dehydrated acid (SSA). The effects of thickness were also studied on the electro-chemical properties of samples on 10 min, 15 min, 20 min, 25 min and 30 min. The optimal performance while using supercapacitor was tested on room temperature with 30.72 F g−1 specific capacitance at 5mVs−1 at 25 min. SEM was used to characterise the surface morphology for 10 min, 15 min, 20 min, 25 min and 30 min. Electrochemical properties were studied with Cyclic Voltammogram from which a maximum specific capacitance value was calculated to be 30.72 F g−1 on 25 min. In this research, super capacitive behaviour was also studied using the electrochemical impedance spectroscopy and galvanostatic discharging-charging technique.

An abaqus-based 3D computer aided design, modelling and simulation of the end-milling operation of stainless steel 301

The need to improve the quality of products, to reduce the machining costs, and to maximize the profit rate calls for deployment of accurate optimisation model for predicting various parameters during milling operation in the manufacturing industries. Incorrect selection of cutting conditions often leads to most defects in milling operations such as inaccuracies in a feature's dimensions or surface roughness, thus compromises the quality of the work-piece being produced. To address the above mentioned issues, this research work employs a computer-aided based modelling and simulation approach to investigate the stress, strain, displacement and thermal distributions during the end milling operation of duplex stainless steel 301. The computer-aided design, modelling and simulation of the milling operation of the material was performed using the commercial software code ABAQUS. A dynamic coupled temperature-displacement computation was employed in the explicit module of the ABAQUS software. The cutting tool and the work piece was first modelled and their computer aided design (CAD) models were imported into the module that is meshed with structured 8-node thermally coupled brick, trilinear displacement and temperature (C3D8RT) mesh elements with reduced integration and hourglass control. The mechanical loading step was carried out from which the thermal step propagates. The result obtained indicate that the stress induced in the work piece was insufficient to cause effective shearing and material removal while the magnitude of the average heat flux was found to be sufficient. The maximum values of the cutting conditions obtained include stress (9.051 MPa), average heat flux (2.102×109w/m2), cutting speed (7700 m/min or 128.359 m/s), strain (3.12×10−13), resultant force (2.147×1010N) and nodal temperature (25°C). It is envisaged that the findings of this work will assist machinist in effective milling operation of stainless steel AISI 301.

Effects of oxygen and water vapour on adhesion of scale grown on ferritic stainless steels in solid oxide fuel cells

The adhesion of thermal oxide scale grown at 800°C on ferritic stainless steel AISI 441 proposed as SOFCs interconnectors was investigated. The influence of oxidising atmosphere was considered by 20% O2-N2 or 20% H2O-N2 as the representative cathode and anode atmospheres, respectively. A tensile test in an SEM chamber was used to assess the adhesion behaviour. The spallation of oxide scale on AISI 441 has to important as the candidate of interconnectors in SOFCs. The adhesion energy was considered as strain energy stored in the oxide, which was calculated at the first spallation of scale. The adhesion energy of scale on steel substrate was shown in the range of 173-214 J m-2. The adhesion energy of scale on steel oxidised in water vapour was higher than that in oxygen. This might be due to the presence of a silica layer at the scale-steel interface of steel oxidised in water vapour. The qualitative assessment of scale adhesion in terms of strain initiating the first spallation suggested the good adhesion behaviour of scale grown in the anode atmosphere.

Residual stress in the carrier tape AISI 310S at the stage of deposition of the YSZ buffer layer when manufacturing of HTS-2G wire

Using neutron diffraction we determined internal residual stress in the stainless steel AISI 310S carrier tape with a thickness of 100 μm and a width of 4 mm after mechanical polishing and the ABAD deposition of the textured YSZ buffer layer. It is shown that mechanical polishing causes a slight distension of the tape in the rolling plane. After the deposition of the YSZ layer, uniform tensile stress of 70 MPa isotropic in the rolling plane was observed inside the tape. Calculations have shown that it results from relaxation of compressive stress acting on the surface of the tape in a layer several times thicker than the YSZ layer. It is assumed that the surface of the tape is plastically deformed during the YSZ deposition. Keywords: residual stress, YSZ buffer layer, HTS-2G wire, AISI 310S carrier tape, neutron stress diffractometry.

On inelasticity of damaged quasi-rate-independent orthotropic materials

The paper deals with a body having a random 3D-distribution of two-phase inclusions: spheroidal mutually parallel voids as well as differently oriented reinforcing parallel stiff spheroidal short fibers. By the effective field approach the effective stiffness fourth-order tensor is formulated and found numerically. Simultaneous and sequential embeddings of inclusions are compared. Damage evolution is described by modified Vakulenko?s approach to endochronic thermodynamics. A brief account of the problem of effective elastic symmetry is given. The results of the theory are applied to the damageelasto- viscoplastic strain of reactor stainless steel AISI 316H.

Effect of pre-microdeformation on ion-plasma nitriding process of stainless stee l AISI 321

In this work the effect of pre-microdeformation — diamond smoothing on the characteristics of the hardened layer of stainless steel AISI 321 after ion-plasma nitriding in a glow discharge was investigated. The study found that at the chosen conditions, the diffusion of nitrogen deep into the samples, without pre-microdeformation before ion-plasma nitriding, is insignificant. It is also found that the pre-microdeformation — diamond smoothing allows for a significant increase in nitrogen diffusion during ion-plasma nitriding, thus contributing to an increase in surface hardness and thickness of the hardened layer of stainless steel AISI 321, which in turn may lead to a significant increase in the resource of finished parts.

Study of Cavitation Erosion Phenomenon at Stainless Steel AISI 304 Base and with SiC Coating

Study of Cavitation Erosion Phenomenon at Stainless Steel AISI 304 Base and with SiC Coating

Ablation threshold estimation for femtosecond pulsed laser machining of AISI 316L

The diffusion of laser machines based on femtosecond and picosecond pulses is increasing in industry, thanks to their capacity of performing high precision, nano-scale machining operations, and to their applicability to a wide variety of materials. The quality of the obtained products depends heavily on the selection of proper machine parameters, which is a non-trivial task for such a nonlinear, multi-physics dependent process. In this work, we propose a new regression approach for the characterization of ablation threshold and incubation factor, which are the key parameters required for defining process recipes in ultra-short pulsed laser machining. The proposed method is applied to the estimation of these parameters for stainless steel AISI 316L, basing on hole drilling data measured by optical microscopy.

Effect of Welding Parameters of Resistance Spot Welding on Mechanical Properties and Corrosion Resistance of 316L

The purpose of this research is to analyze the mechanical properties and corrosion resistance of spot welding of stainless steels AISI 316L using the process of resistance spot welding varying welding parameters with three level for each of welding parameter; welding current (A.), electrode Pressure (bar), squeeze time (s.), and welding time (s.). The welding current was (4500, 5500 and 6500) A, the electrode Pressure was (20, 30 and 40) bar, the squeeze time was (0.6, 0.8 and 1) Sec., and the welding time was (0.3, 0.6 and 0.9) Sec. The specimens were inspected by a tensile-shear test, corrosion test and the inspection of scanning electron microscope (SEM). The technique of design of the experiments (DOE) was utilized to examine the influence of the welding process parameters on the joint tensile-shear force. The results were analyzed by the DOE method to determine the optimum tensile-shear force, where can be obtained by utilizing the welding parameters by welding current 5500A, electrode pressure of 30 bar, squeeze time 0.8s., and welding time of 0.3s. The examination of SEM indicated that the increment of welding current and electrode pressure leads to increment pitting and corrosion rate.

Триботехническая и коррозионная характеристика электроискровых Fe–Al алюминидных покрытий на нержавеющей стали AISI 304

Триботехническая и коррозионная характеристика электроискровых Fe–Al алюминидных покрытий на нержавеющей стали AISI 304

Investigation on thermal analysis of disc brake using Autodesk Fusion 360

Disk brakes are one of the important components in automotive engineering and the material selection for the manufacturing of brake rotors is highly crucial when it comes to the emergency or catastrophe it should withstand the wear and tear, marks the success of the product with the lifetime customer satisfaction. When the brakes are applied a large amount of heat is conveyed on the disk rotors and heat dissipation is based on the material. In this study, three different designs with 40, 64 and 160 drilled holes will be made in the brake rotor and a comparative study has been made between these designs to select the best design. The materials are being selected with their efficient characteristics and designed with the good guidance of it. Thermal analysis is performed with the fusion 360 software with three different materials of the best design obtained from the previous study and simulation performed to determine the heat flux and temperature distribution. The metals which are under consideration are Grey Cast Iron, Aluminium 6061, and stainless steel AISI 430 (SS AISI 430). Based on the results from this study, the candidate material Aluminium 6061 is a superior in various thermal properties (higher heat flux) compare to the other materials (Gray Cast Iron and SS AISI 430) selected in this study for the disc brake and in terms of temperature distribution the material Grey Cast Iron has the highest temperature drop.

In-Situ Monitoring and Defect Detection of Selective Laser Melting Process and Impact of Process Parameters on the Quality of Fabricated SS 316L

Selective Laser Melting (SLM) is an advanced Additive Manufacturing (AM) technique for the 3D printing of metals. SLM process parameters and different types of defects that may appear during the manufacturing process affect the quality of the final product. Setting laser parameters and online defect detection contributes to improving the quality of parts fabricated through SLM technology. In this study, the effect of the process parameters on the properties of the product built by the SLM process was investigated, and an in-situ monitoring platform was developed to detect two types of defects during the SLM process. Different samples were built from stainless steel AISI 316 L powder, utilizing various laser process parameters. Using microscopy imaging technique, the melt structure features of the constructed samples were tested, and the results were analyzed. The dependency of porosity formation on laser process parameters and scan strategy was investigated. Moreover, hardness test was performed for all built samples. The platform developed for in-situ monitoring purposes includes an AM machine equipped with pulsed laser, camera, illumination system, and powerful industrial computer equipped with Cameral Link Adapter, FPGA, and Real-Time (RT) modules. An algorithm was designed using LabVIEW <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">®</sup> software based on Particle Analysis (PA) to cease the process in the event of detection of defect in any fused layers. The first defect was caused by changing the laser spot diameter, which altered the energy intensity of the laser on the surface, and the second defect was created by the uneven thickness of powder on the platform. The monitoring system detected both defects and stopped the process immediately according to the designed algorithm. Images were taken from the melting process layer by layer using a high-performance camera.

Influence of Different Frequency Pulse on Weld Bead Phase Ratio in Gas Tungsten Arc Welding by Ferritic Stainless Steel AISI‐409L

The objective of the present experimental work is to obtain an appropriate welding parameter on pulsed current gas tungsten arc welding (GTAW) ferritic stainless steel AISI 409L with a thickness of 4.5 mm. Frequency affected penetration, and the ratio of bead width to penetration (aspect ratio) is the main objective of the research. A Taguchi L9 orthogonal array with three level four factors was chosen to execute the bead on plate welding. It leads to optimize the input process parameters on main effect plot via analysis of variance, and it has imposed to determine their contribution level of each parameter with respect to responses. Taguchi optimized conditions for butts weld with the pulsed TIG and its surface morphology, and mechanical characteristics of AISI 409L weld was investigated. A full penetration with an optimal aspect ratio was accomplished using high‐frequency pulsing, according to the findings. The mechanical properties were characterized using Vickers microhardness and tensile tests on the base material and weld metals. Microstructural study revealed that these variables have a greater impact on the bead profile. Pulsed TIG showed maximum UTS of 445 MPa and a minimum of 385 MPa, with an average of three samples of 415 MPa. The weld metal in all of the zones had influenced superior tensile strength (UTS) as compared to base metal, according to the findings. The obtained strain percentage for both butt and TIG welds, however, was smaller than that of the parent metal. The formation of martensitic was attributed for the higher tensile strength with minimized ductility of the pulsed TIG welds. Furthermore, results on the hardness are in concurrence with the tensile experiments, as the zone for fusion has a higher hardness than the base metal. Corrosion behavior of the parent metal and welded specimen was analyzed using a potentio‐dynamic polarization technique. The electrochemical behavior of base material and weld samples confirmed that the overall corrosion resistance is better in parent material than the other zones.

Passivation Level of AISI 316L Aseptic Tank Surface Quantified by On-Site Electrochemical Techniques

Frequently stainless steel AISI 316L aseptic tanks have their passivity and corrosion resistance properties degraded by biofilm formation and localized corrosion processes. Thereby, maintenance projects are performed to repair the surface in food-grade product contact to obtain an aseptic property as defined by ASME BPE. However, the on-site non-destructive testing are limited to the liquid penetrant examination and the average roughness measurement. The on-site open circuit potential and on-site cyclic polarization measurements were conducted using a portable electrochemical minicell. The level of passivation was quantified on the tank surface, and it was performed before and after the repairing maintenance protocol be made. The results of the on-site electrochemical measurements showed a clear difference between as-degraded and repaired surfaces, indicating a sensible response to aseptic surface inspection. The on-site open circuit potential together with the on-site cyclic polarization were considered an advanced tool to support the maintenance projects of the AISI 316L aseptic surfaces.