Stainless Steel AISI Research Articles

Residual Stress Analysis in Deep Rolling Process on Gas Tungsten Arc Weld of Stainless Steel AISI 316L

Because of the general problem of the welding workpiece such as fatigue fracture caused by tensile residual stress lead to initial and propagation crack in the fusion zone. Thus, the mechanical surface treatment of deep rolling on Gas Tungsten Arc Welded (GTAW) surfaces of AISI 316L was studied. Deep rolling (DR) is a cold working process to induce compressive residual stress in the surface layer of the workpiece resulting in hardening deformation which increased surface hardness, and smooth surface that inhibit crack growth and improve fracture strength of materials. The present study focuses on compressive residual stress at the surface of stainless steel AISI 316L butt welded joint of GTAW. The three parameters of DR process were used; pressure 150 bar, rolling speed 400 mm/min, and step over 1.0 mm. The residual stresses analysis by X-ray diffraction with sin2Ψ method at 0, 5, 10, and 20 mm from the center of the welded bead. The results showed that the DR process on the welded of GTAW induce the minimum compressive residual stress-408.6 MPa and maximum-498.1 MPa in longitudinal direction. The results of transverse residual stress in minimum and maximum are 43.7 MPa and-34.8 MPa respectively. The FWHM of DR both longitudinal and transverse direction were increased in the same trend. Furthermore, the microhardness after DR treatment on workpiece surface layer higher than GTAW average 0.4 times.

Lutowanie wiązką elektronów na przykładzie stali austenitycznej odpornej na korozję – AISI 304

Electron beam brazing is a joining technology combining the advantages of a precisely controlled heat source and those of vacuum brazing process. The oxide layer decomposes in high-temperature vacuum conditions, which improves the wetting process and, consequently, leads to the obtainment of more favourable properties of the brazed joint. In comparison with brazing in vacuum furnaces, the electron beam brazing process enables the precise heating of selected areas without the necessity of heating the entire element, which, in turn, results in smaller structural changes in the brazed material and the lower consumption of energy. During tests discussed in this article, sheets made of stainless steel AISI 304 were brazed using various copper and silver filler metals. Brazed joints were subjected to microstructural tests and shear strength tests. The results revealed the high efficiency of the electron beam brazing of corrosion-resistant steel sheets using filler metals.

Axial distribution improvements of DLC film on the inner surface of a long stainless steel tube

The internal surface of a stainless steel AISI 304 tube, 200 cm in length and 10 cm in diameter, was coated with diamond-like carbon (DLC) using the Plasma Enhanced Chemical Vapor Deposition (PECVD) technique, using two group of experiments for the entry and exit of the gas flow to determine the effect of their position on the quality and thickness of the DLC film . First, the temperature rise along the tube surface was measured during the argon and acetylene plasma phase. Secondly, the PECVD experiments were analyzed to evaluate the coating for all arrangements used. Thus, the tube temperature, the film thickness, the structural changes and the friction coefficient were measured, using optical microscopy, an infrared Thermometer , a Raman Spectrometer and a pin-on-flat tribometer , respectively. Our measurements revealed DLC films with symmetrical and asymmetrical distributions along the tube. Raman and tribological characterization shown that the lowest I(D)/I(G) ratio and lowest friction coefficient were in the regions with thickest DLC films. The study indicates that DLC films may be grown by PECVD inside of long tubes that exhibit excellent thickness and friction characteristics when entry/exit points for the gas flow are placed at both ends of the tube. • Regions with high temperatures and poor deposition were accompanied by an intense brightness of the plasma; • A reduction in the friction coefficient and tube temperature are ensured with the entry/exit of gas at both ends of the tube; • DLC films grown with the entry/exit of gas at both tube ends proved to be suitable for the internal coating of tubes.

Advances in the understanding of the annular laser beam wire cladding process

This paper experimentally studies the influence of conventional process parameters (laser beam power, P, workpiece, and wire feeding velocities), and the nominal workpiece irradiation proportion WIPN parameter, on ALB-WC process stability and generated clad geometry. The study was based on an extensive set of single clad experiments using stainless steel AISI 316L wire of 0.6 mm diameter and a stainless steel AISI 304 workpiece. The results show that the laser beam power required for a stable process increases non-linearly with WIPN, and this relationship can be described by quadratic regression. An increase in either the workpiece or wire feeding velocity respectively causes a reduction or enlargement of the stability region in the P-WIPN stability diagrams. The influences on stability diagrams are explained by means of the increase in the nominal WIPN to the effective WIPE, as a result of the clad height generated. With respect to clad geometry, it was shown that an increase in the WIPN causes a decrease in the dilution ratio, which is linearly correlated with the workpiece and melt pool temperatures, while clad width and height are not influenced by the WIPN. The paper further explains the complex influences of the process parameters observed on process stability and generated clad geometry using a phenomenological description of the ALB-WC process at a low and high nominal WIPN. For this purpose, heat transfer, Marangoni flow, and laser beam reflections are considered qualitatively and supported by IR and visual images of the wire-end and melt pool as well as the workpiece and melt pool temperatures.

Ovrednotenje mikrobne flore pri pacientih s povečanjem dlesni med obravnavo in analiza površine žičnega loka nesnemnega ortodontskega aparata

Gingival enlargement is a common complication of treatment with a fixed orthodontic appliance, biocompatible stainless-steel archwires AISI 304L (SS). Due to the retention areas, dental plaque accumulation is increased, which results in anaerobic conditions, favourable for periodontopathogenic bacteria. Therefore, it is reasonable to assume that periodontopathogenic bacteria can be found in patients with fixed orthodontic appliances. Organic deposits on the surface of archwires were analyzed. Twenty-one patients with fixed orthodontic appliances and gingival enlargement in the upper dental arch were included in the study. For a determination of the periodontopathogenic bacteria Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedia, Tannerella forsythia and Treponema denticola the molecular microbiological method GenoType Test System was used. For the surface analysis of new and in-vivo exposed SS archwires X-ray Photoelectron Spectroscopy was used. The average probing depth at the baseline was 3.76±0.85 mm. Three types of periodontopathogenic bacteria, namely A. actinomycetemcomitans, T. forsythia and T. denticola, were found to be present. The thickeness of the thin oxide film on new archwires was 8 nm, while organic deposits on the in-vivo exposed archwires was estimated to 60–80 nm. Anaerobic periodontopathogenic bacteria can be found in patients with fixed orthodontic appliances. Therefore, special care is recommended during this kind of treatment.

Prediction of Model Distortion by FEM in 3D Printing via the Selective Laser Melting of Stainless Steel AISI 316L

This paper deals with an experimental analysis of stress prediction and simulation prior to 3D printing via the selective laser melting (SLM) method and the subsequent separation of a printed sample from a base plate in two software programs, ANSYS Addictive Suite and MSC Simufact Additive. Practical verification of the simulation was performed on a 3Dprinted topologically optimized part made of AISI 316L stainless steel. This paper presents a typical workflow for working with metallic 3D printing technology and the state-of-the-art knowledge in the field of stress analysis and simulation of printed components. The paper emphasizes the role of simulation software for additive production and reflects on their weaknesses and strengths as well, with regard to their use not only in science and research but also in practice.

Effect of Magnetic Abrasive Finishing on the Corrosion Behavior by Agricultural Pesticides Corrosive Media

This study investigates the effects of surface quality obtained by Magnetic Abrasive Finishing process (MAF) on the amount of chemical corrosion created by agricultural pesticides. MAF is a relatively new method of finishing which uses a magnetic field to control the abrasive tools. In this study, samples from two types of AISI304 stainless steel and brass 6337 were finished with silicon carbide abrasives having various meshes at three different levels of surface roughness as compared to the control part; the first level was rougher than the control part (400 mesh) and the other two levels were smoother from the control part (Mesh 800 and 1200). The migration rate of metal ions was measured to determine the corrosion rate of samples in terms of ppm by the atomic absorption device in two corrosive environments consisting of Paraquat and Deltamethrin pesticides. The results indicate that, when both pesticides are used, reducing the surface roughness improves the corrosion resistance of samples. In summary, the samples finished with 1200 mesh had the best improvement in increasing the corrosion resistance in both steel and brass (36.11% and 34.85%), respectively. The finished samples with 800 meshes also increased corrosion resistance of AISI 304 and brass 6337 up to 20.54% and 15.72%, respectively. It was also found that the corrosion rate of Paraquat solution was about 4.68 times higher than that of Deltamethrin in the same concentration for both of the working materials. The corrosion rate of brass was also higher than that of steel.

Performance profiling of solid lubricant for eco-friendly sustainable manufacturing

Abstract The intense heat generation during machining is critical to the workpiece quality. Coolant and lubrication therefore play decisive roles in machining. The conventional cutting fluids employed in machining have certain limitations with regards to their use for ecological and economic reasons. However the need for sustainable manufacturing and better surface quality urged to explore the merits of the lubricants that are eco-friendly such as solid lubricants that are proved to be a feasible alternative to the conventional cutting fluids. Solid lubricants, if employed properly, could control the machining zone temperature effectively by intensive removal of heat from the machining zone. If friction at the tool and workpiece interaction can be minimized by providing the effective lubrication, the heat generated can be reduced to some extent. It will also help reduce wear, thus improving the tool life and the surface finish. These are also used to reduce the force and the energy consumption. So the performance of the solid lubricant needs to be evaluated from tribological point of view. For this, an open tribometer has been envisaged to get the friction coefficient between the coated carbide tool and the austenitic stainless steel AISI 304 workpiece at machining - type situations. Hence this study investigate the effects of the machining parameters and the different machining environments on the machinablity aspects namely surface roughness, tool wear, tool - chip contact length, net cutting specific energy, chip morphology and the chip thickness ratio while machining austenitic stainless steel AISI 304 by TiAlN coated tungsten carbide inserts of the different tool geometry. To show the effectiveness of the solid lubricant, a comparative performance analysis, under the different environments was conducted. Results indicate that there is considerable reduction in the average flank wear (35%–60%), net cutting specific energy (40%–49%); tool-chip contact length (40%–60 %), chip thickness ratio (32%–65%) and the surface roughness (10%–39%) with the solid lubricant assisted machining compared to that of wet and dry machining. This study established that the solid lubricant assisted machining is an eco-friendly sustainable manufacturing process for the industry.

The Effect of the Holding Time on the Formation of Niobium-Vanadium Carbide Coating Onto Aisi 420 by Thermo Reactive Diffusion Process

The deep drawing process had been widely used in automobile, aerospace, electronics, and allied industries to produce hollow parts. The quality of the deep drawing is determined by the dies properties especially their wear-resistant and hardness. Austenitic stainless steel AISI 420 is one of the material of choice for making these dies. In order to increase the wear resistance of the dies, surface treatment such as thermo-reactive diffusion (TRD) technique can be applied owing to their simplicity, low cost, and environment friendly process. TRD technique able to deposit hard layers of carbide, nitride, or carbonitride In this research, TRD techniques will be employed to AISI 420 with special attention given to the effect of holding time during TRD process to form niobium-vanadium carbide (NbVC) coating. The TRD process is carried out by the powder-pack method in a sealed steel container containing powder mixture of niobium and vanadium as master alloy, alumina (Al2O3) as an inert filler and ammonium chloride (NH4Cl) as an activator. The samples were covered with powder mixture and then heated in the electric resistance furnace for 2, 4, and 6 hours at 1000˚C. The crosssection analysis of the NbVC coating observed under microscopy shows that coating thickness increased with longer holding time with 6.95 µm measured in 6 hours holding time. The high hardness of 1333.2 HV also found in the longest holding time of 6 hours. This high hardness is expected to contribute in the wear resistance characterisitic of AISI 420 dies.

Corrosion Behavior of Anodic Self-Ordered Porous Oxide Layers on Stainless Steel

In the present study we performed anodization of stainless steel AISI 316L varying the voltage, time and H2O concentration in the electrolyte obtaining self-ordered porous oxides. Open-circuit potential measurements, potentiodynamic polarization and electrochemical impedance spectroscopy were performed in 0.1 M H2SO4, 0.1 M NaCl and 0.1 M NaOH electrolytes. The metallic substrate underneath the grown oxide was also characterized. The results indicate that the corrosion behavior of the metallic substrate is not impaired by the anodization treatments. However, “crevice-induced intergranular corrosion” between the oxide and the metallic substrate was revealed after electrochemical measurements in the acidic electrolyte.

Effect of thermal cycling on the cold rolled AISI 316L with varying degree of reduction toward their microstructure and hardness

Orthopedic implants had been widely used to treat bone fractures. One of the selected materials for an implant is austenitic stainless steel AISI 316L following the ASTM F138 standard. These implants had been produced locally in Indonesia using investment casting method. Even though the mechanical properties of local implant had met ASTM standards requirements, it was found to be lower in their properties as compared to the imported implant from developed countries. In order to compete with these imported products, local implant 316L was modified by reducing their grain size microstructures of about 83.17 µm on average to become finer grain through recrystallization mechanism. The mechanism can be triggered by thermal cycling treatment after 316L was subjected to cold rolling process. The cold rolling process will induce stored strain energy that affects the dislocation density. Different degrees of cold rolling reduction of 52%, 60%, 69%, 80%, and 90% will give different amounts of dislocation density that will affect the recrystallization stage during thermal cycling. It was found that after thermal cycling treatment at 900 C for 35 seconds with 4 cycles, homogenous full recrystallization was confirmed on 80% and 90% reduction degree samples. The average grain size of 80 and 90% reduction degree samples were decreased from 83.17 µm on average detected in the investment casting product to 3.26 µm and 2.87 µm, respectively. This had resulted also in increased average hardness from 159 HV2 to 257 HV2 and 267 HV2 respectively. Conversely, only partial recrystallization was observed in the other degree of reduction samples. The obtained hardness provides lower value than 80% and 90% reduction degree with larger average grain size being detected on these samples.

Grain refinement and mechanical properties for AISI304 stainless steel single-tracks by laser melting deposition: Mathematical modelling versus experimental results

Many of the significant mechanical properties of stainless steel, including ultimate tensile strength, yield strength and hardness, the ductile–brittle transition temperature, and susceptibility to environmental embrittlement, can be improved by grain size refinement. Hall-Petch relation identifies that the improvement can be quantified in a constitutive relation. In this study, a new mathematical model to calculate the number of grains and their average size inside a single printed layer via the laser melting deposition (LMD) process is proposed. The printed layer's thermal history concerning the moving laser beam and co-axial addition of powder debits was analyzed and used to calculate the thermal stress and strain rate. The average grain size within the printed layer was calculated using the Johnson-Mehl-Avrami-Kolmogorov (JMAK) model. The mechanical properties, including ultimate tensile strength, yield strength, and hardness, were estimated using the average grain size. For single depositions of AISI 304 stainless steel powder debits on a steel substrate, dedicated experiments were performed to verify the model’s trustworthiness. Scanning electron microscopy was used to quantify the number and size of grains. Vickers hardness tests were conducted to confirm the mechanical performances predicted by the developed model. It was found that the primary operating parameters strongly influence the grain type, resulting in three varieties of grains: (a) quasi-continuous circular, (b) long lath-shaped, and (c) a combination of the two mentioned above. The deposited layer's thermal history influences the thermal stresses and controls the growing grains' average size. A strong correlation between experimental and computational results, within the range of 10–15 %, and 8–10%, was obtained for the average grain size and Vickers hardness test. The laser scanning speed and laser power were in an inverse relation with the average grain size, while a direct relationship was noticed between the powder feed rate and average grain size. The mechanical computational and experimental results show that the highest yield strength (=208 MPa), ultimate tensile strength (=722 MPa), and hardness (=278 HV) were obtained for the finest grain structure.

Influence of the Thickness of the Reaction Zone in Aluminum/Stainless Steel Brazed Joints on the Mechanical Properties

The study deals with the characterization of the relationship between the microstructure of the reaction zone and the mechanical properties in the brazed joints of aluminum alloy 3003 and stainless steel AISI 304 in order to determine the influence of the intermetallic layers on the tensile shear strength of the joints. The joints were produced by induction brazing using an AlSi10 filler in an argon atmosphere at a temperature of 600 °C. Due to the local heat input into the liquid brazing filler during a short brazing time, a thin reaction zone is formed in the brazed joints (~1 µm), which ensures good mechanical properties of the joints. In order to observe the growth kinetics of the reaction zone in the brazed joints and to investigate the influence of the thickness of the reaction zone on the mechanical properties of the brazed joints, the joints were aged at temperatures of 200 °C and 500 °C for 6, 48 and 120 h. The results have shown that the thickness of this layer increases to a maximum of 2 µm depending on the duration of the thermal aging at a temperature of 200 °C. The results of the tensile shear strength tests have shown that the brazed joints with this thin layer ensure a high strength. The thermal aging at a temperature of 500 °C influences the growth of the reaction zone in the brazed joints significantly. The total thickness of the reaction zone increases to a maximum of 12 µm during the thermal aging. The results of the tensile shear tests of these joints have shown that the thermal aging at a higher temperature leads to a decrease of the tensile shear strength of the brazed joints to 67% due to the growth of the existing intermetallic layer and the formation of a new intermetallic layer in the reaction zone.

Finite Element Analysis of the Magnetic Field Distribution in a Magnetic Abrasive Finishing Station and its Impact on the Effects of Finishing Stainless Steel AISI 304L

In this article, we present a numerical model of a magnetic abrasive finishing station, which was analyzed using the finite element method (FEM). The obtained results were compared with the real values measured on an experimental station of our own design. The prepared station had the option of adjusting the magnetic flux density inside the machining gap, the width of which could be changed from 10 to 30 mm. The maximum value of the magnetic flux density inside the air gap was 0.8 T. The real distribution of magnetic flux density in the finishing area was also analyzed. A design of experiment was carried out with the following variables: abrasive grain concentration, width of the machining gap, and process duration. The results are presented in the form of regression equations and characteristics for selected roughness parameters.

Heat Input Effect on Microstructure and Mechanical Properties in Shielded Metal Arc Welding of Dissimilar AISI 316L/St-37 Steel

Joining of stainless steels to carbon steels is one of the most widely used types of dissimilar joints. In this research, the microstructure and mechanical properties of dissimilar shielded metal arc welding of austenitic stainless steel AISI 316L to carbon steel St-37 is studied. This joining has made by E316L electrode and three heat inputs of 0.72, 0.84 and 1.0 kJ/mm. The microstructure of the joints was characterized by optical and scanning electron microscopy. The mechanical properties of the joints were evaluated by tensile and microhardness tests. The solidification microstructure of the weld metals contained mainly austenite and some skeletal delta ferrite. There was an epitaxial growth at the interface of the weld metal with the AISI 316L steel HAZ, and at the interface of the weld metal with the St-37 HAZ, there is an un-etched narrow area which is suggested to have austenitic-martensitic structure. The results of hardness tests showed that the hardnessof the interface of the weld metal with the St-37 steel was maximum which is attributed to the formation of the martensitic narrow band. The longitudinal tensile results showed that the increasing of the heat input decreaes the tensile strength and increases the elongation of the joints.

Friction Stir Welded AISI 304 Metal Sheets for Application in Food Implants

Stainless steels are indispensable materials in many industrial fields. They can be easily shaped and joined by traditional welding methods. Some problematics such as possible decrease in corrosion resistance at the welding bead and in the heat-effected zone, residual stress, crack formation and distortions may take place after welding. Friction Stir Welding (FSW) may be used for joining stainless steels in a single pass and for optimising microstructure and mechanical properties of the processed region. The application of FSW to the widely used AISI304 stainless steel is investigated in food implants. The mechanical properties together with corrosion resistance and surface finishing are characterized. A high energy input is chosen for the welding (2000 rpm tool rotational speed and 50 mm/min advancing speed). The stirred zone (SZ) is characterized by optical microscopy. Vickers microhardness in the SZ results 37% higher than in the base material. Tensile tests highlight elongations up to 40% keeping maximum stress values at 600 MPa. All samples pass accelerated corrosion tests that simulate 20 years of cleaning cycles in a typical food implant.

Sub-picosecond single-pulse laser ablation of the CrMnFeCoNi high entropy alloy and comparison to stainless steel AISI 304

In recent years, high entropy alloy research has experienced increased interest and it was found that some of these materials have extraordinary properties. High entropy alloys also show an increased damage resistance to high-energy particle irradiation, mainly due to effects caused by the increased configuration entropy. So far, no detailed studies have been carried out regarding the interaction with high-energy electromagnetic radiation, particularly by means of lasers. In this work, we compare results of ultrashort-pulse laser-matter interaction of the CrMnFeCoNi alloy (Cantor alloy), the most researched representative of this material group, with the conventional alloy stainless steel AISI304. Since metals can in general be processed efficiently with ultrashort pulses, which is of particular interest for industrial applications, we performed our experiments with single infrared sub-picosecond pulses. The crater surface morphology and process energetics are discussed in detail and the validity of established ablation models is investigated. We find that the damage threshold of the CrMnFeCoNi alloy is slightly lower than that of AISI304 and consequently CrMnFeCoNi alloy shows an increased ablation volume. Therefore, the high entropy alloy CrMnFeCoNi can be processed efficiently with ultrashort-pulse lasers.

Investigational exploration of EDM process parameters on MRR and surface roughness of AISI304 stainless steel

Electric discharge machining has turn into a vital and cost-effective technique of machining very brittle and tough electrically conductive materials. It is broadly use in compare with the other machining methods of making dies, moulds and sections where the complex dimension and difficult shapes cannot be machined easily. The work-piece material has been chosen for this trial is AISI304 stainless steel assessing its erosion obstruction properties and wide scope of utilizations. Nowadays in world AISI304 stainless steel contributes various sectors like construction, transportation, manufacturing of medical instruments and for industrial goods. Out of various input parameters in EDM process this work was focused on discharge current (Ip), pulse on time (Ton) and pulse off time (Toff). For design of experiment a very famous Taguchi technique is applied to make a L18 orthogonal cluster for input factors. For the dealt with impact of the variable boundaries referenced above after machining reactions, for material removal rate (MRR) and surface roughness (SR) will be carried out with GRA approach for optimization and investigated. Discharge current is the most significant concern while machining on our research findings. The tool material will be chosen as copper electrode. ANOVA were found for the most significant parameters of MRR and SR.

Diffusion enhancement of low-temperature pack aluminizing on austenitic stainless steel AISI 304 by deep rolling process

Diffusion enhancement of low-temperature pack aluminizing on austenitic stainless steel AISI 304 by deep rolling process

Diffusion kinetics of different boronizing processes on martensitic stainless steel AISI 420

Diffusion kinetics of different boronizing processes on martensitic stainless steel AISI 420