Different Types Of Stainless Steel Research Articles

Investigation of Ablation Efficiency of Stainless Steel Using Pulsed Lasers in Burst Mode

Due to its high corrosion resistance and mechanical properties, stainless steel is commonly used in various industrial applications. Although different types of stainless steel are similar in their chemical composition, they can differ significantly in their thermal diffusivity. This property is relevant in the ability of a material to conduct heat and thus, in laser processing. In this frame, this study compares the ablation efficiency and characteristics of polished stainless steel samples of the alloys AISI 304, AISI 420, and AISI 316Ti. They are irradiated with single ultrashort pulses having pulse durations between 250 fs and 10 ps as well as using GHz burst modii. The goal is to investigate the differences in both the ablation threshold and the ablation rate to improve the ablation efficiency. The results show that shorter pulse durations lead to a more efficient ablation process. On the other hand, GHz bursts are found to be, in general, less efficient. In addition, there is a significant difference in the surface morphology depending on the process parameters. The differences in the thermal diffusivity do not significantly influence the ablation threshold fluence but surface morphology and the ablation rate.

Application of machine learning for the classification of corrosion behavior in different environments for material selection of stainless steels

Corrosion behavior prediction of materials in any given environmental condition is important to minimize time-consuming experimental work to avoid failures and catastrophes in industry. Supervised machine learning (ML) techniques are recently explored to predict corrosion behavior. However, there is still a lack of research that proposes a model capable of predicting the corrosion behavior of a wide range of stainless steel grades in varying environments, including acids, bases, and salts. Moreover, conventional experimental approaches are often insufficient in identifying the most influential factors in the corrosion process due to its multivariate and non-linear nature.This study presents the development and evaluation of multiple ML models in predicting the corrosion behavior of different types of stainless steel in varying environments. The prediction performance of four ML algorithms, decision tree (DT), support vector machine (SVM), random forest (RF), and bagging classifier, were compared. Initially, the algorithms were fitted to a dataset based on the type of electrolyte (Dataset No. 1) and then modeled on a modified dataset (Dataset No. 2) in which the types of electrolytes were replaced with their critical ions contributing to corrosion reactions. The Bagging classifier achieved the highest prediction accuracy of 94.4% for Dataset No. 1, while the DT model was the most suitable for Dataset No. 2 with a testing accuracy of 93.95%. The application-driven approach of confusion matrix analysis to select the model’s capacity to correctly identify severe and poor corrosion behavior confirmed that Bagging and DT classifiers are the most suitable ML algorithms for predicting corrosion behavior in Dataset No. 1 and No. 2, respectively. Furthermore, the feature importance analysis identified hydrogen and sulfide concentrations in corrosive environments, as well as the sum of the number of alloying elements, as the most influential factors, contributing up to 77.8% to the corrosion behavior. As a result, users of stainless steels can leverage this model to predict the corrosion behavior of specific materials in specific environments, facilitating informed material selection for various applications, without the need of lengthy and costly experiments.

열교환기용 스테인레스강 열화 용접부의 고온 인장 및 피로특성

Purpose: This study aims to determine the most suitable material for heat exchangers by analyzing the tensile and fatigue strengths of different types of stainless steel, i.e., AISI 310S, AISI 316L, and AISI 347 after welding and aging at both room and high temperatures. BRMethods: Tensile and fatigue tests were performed on three types of stainless steel for heat exchangers using samples aged at 800℃ for 1000 hours and samples that were welded and aged at both room temperature and 800℃. The microstructures of the base material and aged samples were observed using an optical microscope and SEM. The fatigue tests were conducted using a stress ratio of 0.1 and a stress constant test; the fracture surface was then observed using SEM.BRResults: Chromium carbides tend to precipitate more in aged stainless steel samples than in the base material. It was found that AISI 316L stainless steel has the best elongation and fatigue strength at room temperature and 800℃.BRConclusion: In terms of aged and welded samples, AISI 316L stainless steel has the highest elongation and endurance limit. In particular, it has the smallest amount of chromium carbide precipitation at 800℃. In conclusion, it is determined to be an excellent heat exchanger material in terms of weldability, formability, and durability.

Microbiologically influenced corrosion of stainless steel independent of sulfate-reducing bacteria.

The presence and activities of microorganisms on metal surfaces can affect corrosion. Microbial communities after such corrosion incidents have been frequently analyzed, but little is known about the dynamics of microbial communities in biofilms on different types of stainless steels, such as austenitic, martensitic, and duplex stainless steels. Here, we conducted immersion experiments on 10 types of stainless steels in a freshwater environment, where microbiologically influenced corrosion was observed. During 22-month of immersion, severe localized corrosions were observed only on martensitic S40300 stainless steel. Microbial community analysis showed notable differences between non-corroded and corroded stainless steels. On the surfaces of non-corroded stainless steels, microbial communities were slowly altered and diversity decreased over time; in particular, relative abundance of Nitrospira sp. notably increased. Whereas microbial communities in corrosion products on corroded stainless steels showed low diversity; in particular, the family Beggiatoaceae bacteria, iron-oxidizing bacteria, and Candidatus Tenderia sp. were enriched. Furthermore, sulfur enrichment during localized corrosion was observed. Since there was no enrichment of sulfate-reducing bacteria, the sulfur enrichment may be derived from the presence of family Beggiatoaceae bacteria with intracellular sulfur inclusion. Our results demonstrated slow and drastic changes in microbial communities on the healthy and corroded metal surfaces, respectively, and microbial communities on the healthy metal surfaces were not affected by the composition of the stainless steel.

FE modeling of the effect of conductivity in galvanic corrosion between different types of stainless steel and carbon steel in a structure bolted joint

PurposeThis study presents a numerical modeling by the finite element method of galvanic corrosion between the bolt (cathode) and the end plate (anode). The bolt is made of three types of stainless steel: austenitic (SS304L, SS316L), martensitic (SS410, SS420) and duplex (32,101), and the end plate is made of carbon steel (S235JR).Design/methodology/approachFinite element modeling.FindingsThe results obtained show, on the one hand, that this corrosion rate increases as the conductivity increases, on the other hand, the stainless steels having the highest corrosion resistance causes a considerable loss of mass of the end plate and subsequently a decrease in the lifetime of the bolted joint.Originality/valueThe galvanic corrosion of beam to column bolted joint with end plate, used in steel structures, was studied in order to determine the corrosion rate of the end plate and subsequently to predict the total lifetime of the bolted joint.

Corrosion Behavior of Different Types of Stainless Steel in PBS Solution

Anodic and spontaneous corrosion of different types of stainless steel (AISI 304L, AISI 316L and 2205 DSS) in phosphate-buffered saline solution (PBS, pH = 7.4) at 37 °C (i.e., in simulated physiological solution in the human body) were examined using open circuit potential measurements, linear and cyclic polarization, and electrochemical impedance spectroscopy methods. After the anodic and spontaneous corrosion, the surface of the tested samples was investigated by light and scanning electron microscopy (SEM) with EDS analysis. It has been established that the tendency of the examined steel materials towards local corrosion decreases in the order: AISI 304L < AISI 316L < 2205 DSS. Namely, the possibility of repassivation and the resistance to local corrosion increases in the same order. The corrosion resistance of steel samples at open circuit potential is a consequence of forming a natural oxide film with a bi-layer structure and consists of an inner barrier and an outer porous film. The inner barrier film has a small thickness and extremely high resistance, while the outer porous film is much thicker but also has significantly lower resistance. The inner barrier layer mainly prevents corrosion of examined steel samples in order: AISI 304L < AISI 316L < 2205 DSS. Light microscopy and SEM/EDS analysis after pitting and spontaneous corrosion showed damage on the AISI 304L and AISI 316L surface, while the surface of 2205 DSS was almost undamaged by corrosion.

Experimental investigation on aluminium alloy AA6061 and AA8011 using friction stir welding

Friction Stir Welding (FSW) is a solid-state joining process that involves joining of metals without fusion or filler materials. The process is particularly applicable for aluminum alloys but can be extended to other products also like steels. The project was mainly founded by National Technological Agency of Finland. The friction stir welded joints of austenitic and ferrite stainless steels were implemented at different rotational speeds 500 ∼ 1100 rpm. The results showed that increasing rotating speed enhanced heat input and material movement in the welded zone, and the nugget zone had a blocky, laminated, and vortex structure of austenite and ferrite. In this investigation, different combinations of tool rotation speeds and tool transverse speeds are used to connect different types of stainless steel. Following an overview of the macroscopic characteristics, the micro structure development and associated hardness tensile and impact results and distributions are discussed.

Modified austenitic stainless-steel alloys for sheilding nuclear reactors

In this study, seven different steel alloys are based on the nominal composition of free cobalt, although cobalt is one of the alloying composite elements, but it is expensive; Therefore, we proceeded to prepare cobalt-free stainless steel by using an electro slag re-melting technique as a radiation shield to reduce production cost. The proportions of the steel compound were determined using XRF techniques. The gamma and neutron shielding properties of 7 different types of stainless steel have been investigated. We have calculated the mass attenuation coefficient (μ/ρ), half value layer (HVL), and effective atomic number (Zeff) for total photon interaction in the wide energy range of 80 keV–1333 keV using hyper pure germanium (HPGe) detector and WinXCOM computer program. Furthermore, the macroscopic effective removal cross-sections (∑R) for fast neutron were calculated. The dependence of different parameters on incident photon energy and chemical content has been discussed. Among the selected cobalt-free alloy steels, No. A6 with density 8.28 g/cm3 showed superior gamma ray and neutron shielding properties. This work was carried out to explore the advantages of alloy steels in gamma and neutron protection applications.

Investigation of mechanical, kinetic and corrosion properties of borided AISI 304, AISI 420 and AISI 430

ABSTRACT In this study, three different types of stainless steels, AISI 304, AISI 420, and AISI 430 were pack borided under 850 °C–925 °C–1000 °C for 2, 4, and 6 h, respectively. Morphologies of coating were investigated by optical and scanning electron microscope (SEM). The maximum layer hardness was determined to be 1736 HV0.05, 1659 HV0.05, and 1572 HV0.05 for AISI 304, AISI 420, and AISI 430, respectively. Phases formed on the layer were determined by X-ray analysis (XRD) to confirm the presence of FeB, Fe2B, CrB, and MnB phases. Boride layer morphology was found to be a planar and compact structure. The activation energies of the coating were investigated. The corrosion resistance values of stainless steels were determined from the static immersion tests performed in 10% HCl solution. There was a remarkable increase in the corrosion resistance of borided steel compared to that of untreated samples.

Proton exchange membrane (PEM) fuel cell bipolar plates prepared from a physical vapor deposition (PVD) titanium nitride (TiN) coated AISI416 stainless-steel

Metal nitrides (and particularly TiN) are among the most extensively investigated proton exchange membrane fuel cell bipolar plates (BP) coatings. The most employed methods of nitrides coating deposition are various modifications of physical vapor deposition (PVD), while different types of stainless steels are the most common BP materials coated with TiN PVD films. In the current work, we report on the integrity maintenance of TiN PVD coating of AISI416, considering this as a clue to the sustainability of such a film. The advantage of this combination lies in the fact that the coefficients of thermal expansion (CTE) of this alloy is close to the CTE of the TiN film. Thus, the thermal stresses of such coating are expected to be minimal, as well as related coating cracks. We conducted a thorough surface analysis of roughness evolution in the course of BP corrosion process, investigating different initial surface pretreatments. Finally, we found that fine mirror-like polished BP substrate prior to deposition is essential for TiN film’s integrity during corrosion analysis time.

Performance test to evaluate the corrosion resistance of stainless steel in concrete

Abstract Stainless steel is a possible measure for increasing the service life of reinforced concrete structures exposed to chlorides. For the prediction of service life it is crucial to quantify the corrosion resistance of the material used by determining the chloride threshold at the steel concrete interface inducing corrosion at the rebar. However, currently the corrosion resistance of stainless steel is expressed by its pitting resistance equivalent number (PREN) which considers only the content of chromium, molybdenum and nickel along with certain factors. The higher the PREN-value, the more corrosion resistant the steel. But this PREN-value cannot be transferred into a chloride threshold concentration. Therefore, this paper presents a test method, the so called “ECISS”-test (ECISS = European Commission for International Steel Standardization), which enables the evaluation of the chloride threshold of stainless steel. The focus is on the performance of this test with respect to its limits and opportunities. Test results of different types of stainless steels are included and discussed. The benefit of stainless steel with respect to the service life of reinforced concrete structures is highlighted.

Characterization of Vertically Aligned Carbon Nanotube Forests Grown on Stainless Steel Surfaces.

Vertically aligned carbon nanotube (CNT) forests are a particularly interesting class of nanomaterials, because they combine multifunctional properties, such as high energy absorption, compressive strength, recoverability, and super-hydrophobicity with light weight. These characteristics make them suitable for application as coating, protective layers, and antifouling substrates for metallic pipelines and blades. Direct growth of CNT forests on metals offers the possibility of transferring the tunable CNT functionalities directly onto the desired substrates. Here, we focus on characterizing the structure and mechanical properties, as well as wettability and adhesion, of CNT forests grown on different types of stainless steel. We investigate the correlations between composition and morphology of the steel substrates with the micro-structure of the CNTs and reveal how the latter ultimately controls the mechanical and wetting properties of the CNT forest. Additionally, we study the influence of substrate morphology on the adhesion of CNTs to their substrate. We highlight that the same structure-property relationships govern the mechanical performance of CNT forests grown on steels and on Si.

Comparison of critical flow velocity for erosion-corrosion of six stainless steels in 3.5 wt% NaCl solution containing 2 wt% silica sand particles

Critical flow velocity (CFV) is one of the valid parameters to evaluate the erosion-corrosion performance of passive materials. The comparison of CFV for common passive materials is significant for the engineering applications. This study focuses on the comparison of CFV for different types of stainless steel (SS), including the pearlitic 2Cr13 SS, austenitic 304 SS, 316 SS, 254 SMO SS, and two duplex stainless steels (DSS) (2205 DSS and 2507 DSS) in 3.5 wt% NaCl solution containing 2 wt% silica sand particles using the impingement jet apparatus. Different methods (potentiostatic polarization tests, mass loss measurements and surface roughness measurements) were used to determine the CFV and the values of CFV derived from different methods showed a good consistency. The 254 SMO SS exhibited the highest CFV, followed by 2507 DSS, 2205 DSS and 316 SS, and 304 SS and 2Cr13 SS. Compared with the mass loss method which is normally time-consuming, comprehensive evaluation based on the critical flow velocity and current density at flow velocity higher than the critical value by using potentiostatic polarization tests is more effective and efficient for the material selection for erosion-corrosion.

New Industrial Alloy for Molten Salt Application: Design and Properties

Molten salts (MS) can be used for nuclear fuel reprocessing (NFR) and as a working media in molten salt nuclear reactors (MSNR). However, application of MS in NFR and MSNR technologies is limited by the problem of finding suitable corrosion resistance materials. In the present work the results of examining structure and properties of a new prospective alloy are presented. Existing corrosion-resistant alloys are normally manufactured for an intended application in aggressive aqueous-based media, whereas high-temperature alloys are mostly designed for aerospace industry where high mechanical strength under extreme conditions is required. On the basis of the comprehensive studies of corrosion resistance of different types of stainless steels and nickel-based superalloys we concluded that a new alloy with a “nickel–chromium–molybdenum” matrix is required for molten salts applications. In the present work the results of the new alloy fabrication process and detailed examination of the alloy’s properties are presented. The requirements for the alloy composition were determined on the basis of thermodynamic calculations (Thermocalc Software AB was used to simulate the phase content) and previously obtained experimental data on metals and alloys corrosion in molten chlorides and sensibility of these materials to the intergranular corrosion. Carbon content in the material should be maintained at a minimal level. The influence of other elements presence on stability of the γ-phase austenite matrix was analyzed. The alloy of the required composition was produced by induction vacuum melting in several stages. First a low carbon Ni–Mo master-alloy was manufactured. Then this master alloy was further melted and chromium and microelements added. Sheet, tube, rod and forged samples were fabricated. Mechanical and thermophysical properties, susceptibility to the intergranular corrosion of this new nickel alloy in the “as received” state were investigated. The results obtained correlated well with the properties of typical nickel-based superalloys with austenite structure. In a special series of experiments thermodynamic stability of the fabricated alloy was studied. No formation of carbide phases was observed. Phase structure of the excessive intermetallic phases was characterized. The constructed “time – temperature – precipitation” diagram allowed to determine maximum temperature and time of alloy’s operation in contact with molten salts. The phase stability of the alloy designed exceeded that of a variety of other nickel-based superalloys. The corrosion resistance of the material was studied in molten KCl-AlCl3 and 3LiCl-2KCl electrolytes at 450–750 °C. Chloroaluminates are prospective media for the second loop of MSNFR and acidic KCl-AlCl3 electrolytes are very corrosive compare to other chloride mixtures. From the other hand, 3LiCl-2KCl system is a prospective medium for NFR technologies. To model the worst possible conditions for the alloy, the electrolytes containing excess aluminum chloride were selected for the present investigation. Time of exposure varied from 6 to 1000 h, and the samples were tested in the “as received” state as well as after typical technological manipulations (bending, welding, heat treatment, etc.). Metallographic analysis showed that the alloy was subjected to slow frontal corrosion up to 550 ºC (Figure). Experimentally determined corrosion rates were below 50μm/year depending on the melt composition. The surface of the corroded samples was slightly depleted in chromium. Formation of secondary phases was not observed. Excessive sigma phases along the grain boundaries were formed after 100 h exposure at 650 ºC in the surface layer and after 512 h in the bulk of the material. Formation of the secondary phases in the surface layer was caused by selective chromium leaching and degradation of the nickel-based solid solution. Prolonged contact of the material with the high-temperature melt led to unavoidable decomposition of thermodynamically metastable nickel-based austenite. Such behavior correlates very well with the constructed “time – temperature – precipitation” diagram. Using the alloy at such temperatures (650 oC and above) becomes undesirable due to possible development of integranular corrosion. Figure. Microstructure of the new alloy after 100 h exposure in KCl–AlCl3 melt at 450 (a, b); 550 (c, d) and 650 °С (e, f) Figure 1

Mechanical Behavior of Stainless Steel Fiber-Reinforced Composites Exposed to Accelerated Corrosion.

Recent advancements in metal fibers have introduced a promising new type of stainless steel fiber with high stiffness, high failure strain, and a thickness < 100 μm (<0.00394 in.) that can be utilized in a steel fiber-reinforced polymer. However, stainless steel is known to be susceptible to pitting corrosion. The main goal of this study is to compare the impact of corrosion on the mechanical properties of steel fiber-reinforced composites with those of conventional types of stainless steel. By providing experimental evidences, this study may promote the application of steel fiber-reinforced composite as a viable alternative to conventional metals. Samples of steel fiber-reinforced polymer and four different types of stainless steel were subjected to 144 and 288 h of corrosion in ferric chloride solution to simulate accelerated corrosion conditions. The weight losses due to corrosion were recorded. The corroded and control samples were tested under monotonic tensile loading to measure the ultimate stresses and strains. The effect of corrosion on the mechanical properties of the different materials was evaluated. The digital image correlation (DIC) technique was used to investigate the failure mechanism of the corrosion-damaged specimens. Overall, steel fiber-reinforced composites had the greatest corrosion resistance.

Corrosion Resistance of TIG Welded Joints of Stainless Steels

The aim of this work was to analyze the performance of joints made by TIG (Tungsten Inert Gas) welding process in austenitic and duplex stainless steels with special regards to their corrosion resistance. Three different types of stainless steel were butt welded with TIG method. Ferric-chloride test and electrochemical treatments revealed how does the TIG process affects the corrosion resistance depending upon the alloy used for welding the joint. This work focuses on the weldability of the 2304, 2404 and 304 type stainless steel heterogeneous welds.

Corrosion of stainless steels and low-Cr steel in molten Ca(NO3)2–NaNO3–KNO3 eutectic salt for direct energy storage in CSP plants

The corrosive effects of a molten nitrate mixture of 48% Ca(NO3)2+7% NaNO3+45% KNO3 were appraised at 390°C on two different types of stainless steels (AISI 304, 430), a low-Cr alloy steel (T22) and a carbon steel (A1).The corrosion rates were determined using gravimetric tests, which measured the weight gain during 2000h to identify the corrosion products with scanning electron microscopy (SEM) and X-ray diffraction (XRD).Studies on stainless steel revealed a better behaviour in corrosive environment, which mainly identifies the formation of (K,Na)CrO4 protective spinel.Fe2O3 and Fe3O4 were the other important products that were found in the tests performed at 390°C; the formation of some stable compounds with salt impurities, such as carbonates and sulphates, was also observed.

Statistical evaluation of a new resistance model for cold-formed stainless steel cross-sections subjected to web crippling

This paper presents a statistical evaluation according to Annex D of EN 1990 (2002) of a new resistance function for web crippling design of cold-formed stainless steel cross-sections. This resistance function was derived by Bock et al. (2013) through the use of carefully validated numerical models with the aim to propose a design expression for stainless steel sections, which are currently designed following the provisions for cold-formed carbon steel sections given in EN 1993-1-3 (2006). Although it was shown that the proposed design equation is appropriate for application to various stainless steels, the statistical uncertainties in material properties that the different types of stainless steels exhibit require an assessment of various partial safety factors. The statistical assessment showed that the proposed resistance function by Bock et al. (2013) requires adjustment to satisfy the safety level set out in EN 1993-1-4 (2006); A recalibration is performed herein. The web crippling design provisions given in EN 1993-1-3 (2006) and SEI/ASCE 8-02 (2002) American standard for application to stainless steel are also statistically evaluated herein. Comparison with test and numerical data showed that the predictions of the recalibrated resistance function are better suited and consistent than existing design provisions.

Comparative study of erosion–corrosion performance on a range of stainless steels

Erosion–corrosion is one of the most severe types of material deterioration that occur in hydraulic machinery. Corrosion resistant alloys perform well in some marine applications. These materials do have their limitations, though, and for this reason a comparison of their performances is significant. This study focuses on the assessment of the relative behaviour of four different types of stainless steel (UNS S31600, UNS S32760, UNS S42000, and UNS S17400) in erosion–corrosion environments. The study was expanded to include a carbon steel (UNS G10400). Test pieces have been investigated in a submerged jet impingement apparatus in 3.5% NaCl solution with suspended solid particles at temperatures of 30–35°C. In situ corrosion monitoring was also undertaken and the influence of the application of cathodic protection was studied. This facilitated assessment of the relative roles of erosion, corrosion and synergy on the overall degradation processes. A variety of examination techniques were utilised (i.e. mass loss, surface profiling, microscopy) in order to obtain detailed information on those different modes of attack. Differences between stainless steels and carbon steel were observed and the superduplex stainless steel exhibited the best performance of the four types of stainless steel investigated herein.

A new design method for stainless steel columns subjected to flexural buckling

The objective of this paper is to develop a design method for stainless steel columns subjected to flexural buckling. In this method, the strength curve for every type of stainless steel in common use is generated by using the base strength curves and a slenderness conversion formula. A validated finite element model is employed to generate the strength curves for different types of stainless steels. According to the strain hardening exponent n in the Ramberg-Osgood material model, cluster analysis is conducted to separate these strength curves into two groups. In each group, one type of material parameter is selected as the base material and the corresponding strength curve is expressed in the form of a modified Perry formula that serves as the base strength curve. A slenderness conversion formula is derived for any two stainless steel columns with the same section type and boundary conditions, but with different types of stainless steel. Based on the base strength curves and the slenderness conversion formula, the strength curve for every type of stainless steel in common use can be generated. The predictions of the proposed method show a good agreement with the results of the finite element analysis.