Characteristics Of Austenitic Stainless Steel Research Articles

Impact of Cu and Ce on the electrochemical, antibacterial, and wear properties of 316 L stainless steel: Insights for biomedical applications

This study provides a comprehensive investigation of the tribological, electrochemical, and antibacterial characteristics of austenitic stainless steel, type 316 L, doped with Ce and Cu. The samples were doped with varying concentrations of Ce (0.5, 1.5, and 3 wt%) and Cu (1.5, 2.5, and 3.5 wt%). The initial measurements focused on determining the final density values of each sample. Subsequently, friction wear tests were conducted under both dry and wet conditions, shedding light on the wear resistance of the materials. In addition, electrochemical polarization tests were employed to assess the influence of Ce and Cu on the corrosion resistance of AISI 316 L. Furthermore, antibacterial assessments were conducted against bacterial cultures of Staphylococcus aureus (ATCC 29213) and Escherichia coli (ATCC 25922). The findings of this study illuminate several noteworthy outcomes. Namely, the results showed that all Ce and Cu-doped samples exhibited an increase in final density values when compared with the as-received AISI 316 L. The wear test results revealed that samples doped with 0.5 wt% Ce and 2.5 wt% Cu exhibited the highest wear resistance, in both dry and wet environments. Polarization curve analysis indicated that Ce was more effective in enhancing the corrosion resistance of AISI 316 L than Cu. Notably, Ce and Cu modifications endowed the material with antibacterial properties, effectively inhibiting bacterial growth in both S. aureus and E. coli cultures. In summary, this study demonstrates that the addition of even trace amounts of Ce and Cu to AISI 316 L leads to noticeable improvements in the material's tribological, electrochemical, and antibacterial performance, underscoring its potential for diverse biomedical applications. The enhanced mechanical strength, corrosion resistance, and antibacterial activity make the doped material promising for use in various medical devices, implants, and other biomedical applications.

A comparative study on hysteretic characteristics of austenitic stainless steel and carbon steel slit dampers under cyclic loading

Steel slit dampers were designed and fabricated for earthquake-resistant structures using austenitic stainless steel STS304 (ASTM type 304), and carbon steel SS275 (ASTM A36). Monotonic loading and cyclic loading tests were conducted for the materials and steel slit dampers. Monotonic material test results indicated that the tensile strength and elongation of STS304 material were superior to those of SS275. The repeated tests showed that the STS304 steel damper subjected to constant amplitude and incremental amplitude cyclic loading exhibited higher strength ratios and energy dissipation capacity than the SS275 damper until ultimate strength step and 30 mm displacement (story drift) on the skeleton curve of the stainless steel damper after yielding. However, the austenitic stainless steel (STS304) dampers exhibited brittle behavior under cyclic loading due to transformation induced plasticity (TRIP). The total number of cycles at the time of tensile fracture and compressive buckling occurrence was smaller than that of the carbon steel damper except for some specimens with short constant amplitude loading protocol, and thus the total energy dissipation capacity of austenitic stainless steel damper was also found to be on average 95% of that of the carbon steel damper. On the other hand, within the specified low cycle number of loading protocol and allowable story drift of retrofitted building, austenitic stainless steel STS304 slit damper possessed the excellent seismic performance. Finally, the predicted yield strength of the damper was compared with test yield strength and the effect of the cyclic plastic hardening on the yield strength of steel slit damper was also discussed.

The effect of cyclic deformation on the mechanical, elastic and acoustic characteristics of austenitic stainless steel

The effect of elastoplastic cyclic straining on the elastic and acoustic characteristics of austenitic stainless steel AISI 321 is investigated. A change of the elastic characteristics of austenitic stainless steel associated primarily with martensitic transformations that affect the accumulated energy density is found. The influence of the amplitude of strain cycle on development of the elastic anisotropy is analyzed. The possibility of determining the stress amplitude of the fatigue loading cycle by an acoustic method involving measuring the elastic characteristic of the material has been demonstrated. The relationship between changes of elastic characteristics and damage is suggested; it can be used for evaluation of fatigue life by the acoustic method.

Effect of Active Screen Plasma Nitriding on Fatigue Characteristics of Austenitic Stainless Steel

Effect of Active Screen Plasma Nitriding on Fatigue Characteristics of Austenitic Stainless Steel

Basic Kinematic Hardening Rules Applied to 304 Stainless Steel and the Advantage of Parameters Evolution

Cyclic plasticity models for the description of the deformation characteristics of austenitic stainless steel 304 at a room temperature have been studied with the focus on its industrial use. The main objective of this work is to investigate the capabilities of the classical Chaboche model with four terms which is commonly used in practice, and to compare those capabilities with the same model enriched with the evolution of some kinematic hardening parameters. The incorporation of parameters evolution brings significant number of necessary parameters to be determined, compared to the classical Chaboche model with four terms. To overcome excessive number of necessary parameters, also two terms Chaboche model with parameters evolution is used. Presented paper evaluates the time and temperature independent modeling possibilities of Chaboche combined nonlinear kinematic hardening model and isotropic hardening model with von Mises yield criterion.

The effect of phase transformations induced by cyclic loading on the elastic properties and plastic hysteresis of austenitic stainless steel

The effect of low-cycle fatigue on the elastic and acoustic characteristics of austenitic stainless steel AISI 321 is investigated. The relation between characteristics of the hysteresis loop and changes of the acoustic parameters is established. A change of the elastic characteristics of austenitic stainless steel associated primarily with martensitic transformations that affect cyclic hardening, the width of the hysteresis loop, energy loss in the cycle, and the accumulated energy density is found. The influence of the amplitude of strain cycle on development of the elastic anisotropy is analyzed. The relationship between changes of elastic characteristics and damage is suggested; it can be used for evaluation of fatigue life by the acoustic method.

Effect of atmospheric-controlled induction-heating fine particle peening on electrochemical characteristics of austenitic stainless steel

Atmospheric-controlled induction-heating fine particle peening (AIH-FPP) using Cr and Mo shot particles in a N2 atmosphere was introduced to improve the electrochemical characteristics of AISI 316 austenitic stainless steel. The surface microstructure of the AIH-FPP-treated specimen was characterized using scanning electron microscopy (SEM) and energy dispersive X-ray spectrometry (EDX). AIH-FPP can be used to form transferred and diffused layers of shot particles on the surface of austenitic stainless steel. The thickness of the diffusion layers of Cr shot particles tended to increase with the heating time in the AIH-FPP process, whereas the Cr concentration at the surface tended to decrease. Electrochemical polarization tests were performed in 3wt% NaCl+H2SO4 and 20wt% NaCl environments at 343K using a three-electrode electrochemical cell connected to a computer driven potentiostat to examine the corrosion resistance of austenitic stainless steel treated with AIH-FPP. The pitting potential of the AIH-FPP-treated specimen was higher than that of the untreated specimen. In particular, there was clear improvement in the pitting potential of austenitic stainless steel by AIH-FPP with Cr shot particles following peening with Mo shot particles. AIH-FPP using Cr and Mo shot particles in a N2 atmosphere is an effective method of improving the electrochemical characteristics of austenitic stainless steel.

Electrochemical Characteristics of Austenitic Stainless Steel in Mixed Chloride - Molybdate Solutions

The effect of molybdate addition to chloride solutions on resistance of AISI 316Ti stainless steel to pitting corrosion was studied. Potentiodynamic polarization tests were performed in 1 M and 0.1 M chloride acidified solutions with various additions of sodium molybdate at room temperature. The presented results compare the effect of molybdate anions on quality of passive film (expressed by the pitting potential) in both chloride solutions. The pitting potential increases with the increase of inhibitor concentration. The inhibitive effect of molybdate ions is stronger in chloride solution of lower aggressiveness (0.1M).

Relationship between sensitization and magnetic characteristics in 304 stainless steel

We investigated the relationship between sensitization and magnetic characteristics of austenitic stainless steel with different composition. The saturation magnetization increased with increasing heat treatment time and the coercivity increases at first and then decreases for the specimens with hi gher carbon content. The changes in magnetic properties are not remarkable for the specimens with lower carbon content. The area where the chromium carbides formed yields chromium depletion zone and shows ferromagnetic properties. Chromium depletion zone induces martensitic transformation because the martensitic transformation temperature rises. The obtained results indicate that sensitization is detectable using magnetic measurement.

Fatigue crack growth characteristics of austenitic stainless steel for cold‐stretched pressure vessels at cryogenic temperatures

Cold‐stretched pressure vessels made from austenitic stainless steel are widely used for storage and transportation of liquefied gases. Compared with conventional pressure vessels, cold‐stretched vessels have lots of advantages such as having thin walls, light weight, and low energy consumption. However, pressure vessels can be subjected to alternating loads at cryogenic temperatures, so it is important to investigate the fatigue characteristics of austenitic stainless steel for cold‐stretched vessels. This study presents the static and fatigue behavior of austenitic stainless steel 304 sampled from cold‐stretched pressure vessels in accordance with the American Society of Mechanical Engineers code. To compare the mechanical properties and fatigue behavior of austenitic stainless steel 304 in as‐received and cold‐stretched conditions (9 % strain level), tensile and fatigue crack growth tests were performed at room and cryogenic temperatures respectively. Fractography of the fractured specimens was carried out using a scanning electron microscope.

Sensitizing Effects of Ti Alloying Contents on Damage Behavior of Austenitic Stainless Steel Exposed to Ultrasonic Vibratory Cavitation

The cavitation damage characteristics of austenitic stainless steel with different concentrations of Ti were investigated. The microstructure of the alloys was observed with optical microscope to identify its correlation with cavitation resistance. Hardness of the alloys was measured to examine its contribution to cavitation damage. It was found that the microstructure played a more significant role in cavitation damage behavior of austenitic stainless steel with Ti than the hardness. The findings in this study revealed that Ti addition in austenitic stainless steel may present either a beneficial or detrimental effect on cavitation damage behavior, depending on the microstructural characteristics. In particular, Ti content of 1.0% represented the most deteriorated cavitation characteristics due to the formation of relatively coarse precipitates. Therefore, control of Ti concentration is essential for marine application of austenitic stainless steel.

Effect of Alloying Tin on the Corrosion Characteristics of Austenitic Stainless Steel in Sulfuric Acid and Sodium Chloride Solutions

The effect of tin on general and pitting corrosion behaviors of the austenitic stainless steel in sulfuric acid and sodium chloride solutions was investigated by potentiostatic critical pitting temperature, cyclic potentiodynamic polarization, electrochemical impedance spectroscopy, and scanning electron microscopy. The results showed that there is an optimal tin addition which is around (0.062–0.1) wt%, and the general corrosion resistance of B316LX with 0.08 wt% tin addition in boiling H2SO4 increased remarkably with a corrosion rate of an order of magnitude lower than that of 316L. Hydrolyzation of tin ions induces more metastable pit occurrence on the material surface. However, the pitting resistance of B316LX increases because tin oxides improve the density and uniformity of the passive film, and hydroxide and oxide of tin inhabit the process of pit growing. The effect of tin on pitting corrosion process is illustrated schematically.

Effect of Rare Earth Elements on Machining Characteristics of Austenitic Stainless Steels without Lead Addition

Rare earth elements (REE) are harmless for human health. REE addition contributes to the improvement of the machinability of the steels. In the present paper, machining characteristics of austenitic stainless steels without lead addition were investigated by adding free-machining elements, such as sulfur, REE and bismuth. The results have shown that large numbers of rounded, globular shaped inclusions were obtained for both steels. The machinability of steel B is better than that of steel A, and the cutting forces of steel B are lower than those of steel A at various cutting speeds. Lead can be substituted by REE and bismuth in free machinable austenitic stainless steels. REE significantly affects machining characteristics of austenitic stainless steels without lead addition. The mechanical properties of both steels were similar, and their fracture exhibited ductile characteristics. Satisfactory machinability and mechanical properties can be obtained for both steels.

Experimental Investigation into Electrical Discharge Machining of Stainless Steel 304

This study presents the experimental investigation of the machining characteristics of austenitic stainless steel 304 through electric discharge machining. The effectiveness of the EDM process with stainless steel is evaluated in terms of the removal rate (MRR), the Tool Wear Rate (TWR) and the surface roughness of the work-piece produced. The experimental work is conducted utilizing Die Sinking electrical discharge machine of AQ55L model. Cylindrical copper electrode having a size of 019*37 mm and positive polarity for electrode (reverse polarity) is used to machine austenitic stainless steel 304 materials. The work material holds tensile strength of 580 and 290 MPa as yield strength. The size of the work-piece was 022*30 mm. Investigations indicate that increasing the peak current increases the MRR and the surface roughness. The TWR increases with peak ampere until 150 ja sec pulse-on time. From the experimental results no tool wear condition is noted for copper electrode at long pulse-on time with reverse polarity. The optimal pulse-on time is changed with high ampere.

Effects of Dissolved Oxygen on Fatigue Characteristics of Austenitic Stainless Steel in 0.9wt% Sodium Chloride Solutions

Fatigue life evaluations in low dissolved oxygen conditions have been found to be conservative regarding the prediction of the fatigue strength of biomaterials. However, dissolved oxygen is considered to increase crack propagation rates. It is necessary to observe whether the strength in low dissolved oxygen conditions is higher. In this paper, the authors observed the effects of dissolved gas on the corrosion fatigue characteristics of austenitic stainless steels. Fatigue strength was higher with low dissolved O2 NaCl aq at a stress ratio of R= 0.1. However, fatigue strength did not change with low dissolved O2 NaCl aq at a stress ratio of R= 0.5 because of the effect of work hardening. Cycles to crack initiation were longer and crack growth rates were lower in the low dissolved O2 NaCl aq. The mechanism of decreasing fatigue strength can be explained by the oxidation process during slipping. In conclusion, dissolved oxygen has the effect of accelerating crack propagation processes.

Effects of dissolved oxygen on fatigue characteristics of austenitic stainless steel in 0.9wt% sodium chloride solutions

Fatigue life evaluations in low dissolved oxygen conditions have been considered as conservative in predicting fatigue strengths of biomaterials. However, dissolved oxygen is considered to increase crack propagation rates. It is necessary to observe whether the strength in low dissolved oxygen conditions becomes higher. In this paper, authors observed effects of dissolved gas on corrosion fatigue characteristics of austenitic stainless steels. Fatigue strength becomes higher in low dissolved O2NaClaq. at stress ratio R=0.1. However, fatigue strength did not change in low dissolved O2NaClaq.at stress ratio R=0.5 because of the effect of work hardening. Cycles to crack initiations became longer and crack growth rates became lower in low dissolved O2NaClaq..In conclusion, dissolved oxygen has effects of accelerating crack propagation processes.

Discussion of “Microstructural and Stress Corrosion Cracking Characteristics of Austenitic Stainless Steels Containing Silicon”

The authors investigate the effect of Si on the susceptibility of austenitic steels intended for use in nuclear light water reactors to irradiation-assisted stress corrosion cracking. However, regrettably, they admit to inconclusive results. It seems that some other important factor may be over-riding their results. I write to draw attention to the probability that oxide bifilms (oxide films entrained during the original pouring of the steel) seem likely to be the dominant factor in this research, and may have been overlooked. This writer has recently drawn attention to the effect of bifilms on stress corrosion cracking in Al-Mg alloys. The effect seems to be not confined to light alloys, but appears to be a general metallurgical problem. If the surface film on the original liquid metal is folded into the melt during the pouring of the ingot, the film folds in double, with its dry ceramic surface folded opposed and unbondable, thus acting as a crack in suspension in the liquid. Highly turbulent handling of melts can fill a liquid metal with a huge density of cracks. The cracks are naturally frozen into the solid if solidification is sufficiently rapid. The experimental technique described by the authors is particularly susceptible to the formation of a generous population of bifilms in their final microstructure. The pouring of the melt in a vacuum induction furnace necessarily involves a significant drop of the melt (by a meter or more) into a mold. The relatively poor industrial vacuum is well known for being highly effective for oxidizing melt surfaces during the pour. The mold would have been iron or steel, and so would have rapidly frozen the copious numbers of bifilms in place before they had a chance to float out. The subsequent vacuum arc remelting (VAR) would have introduced a second crop of serious bifilms in the ‘‘pancake style’’ folding of the oxide surface in this extremely inappropriate melting process. The VAR is well known to produce ingots of reactive alloys that are practically unworkable (for instance, VAR ingots of the Ni-base alloy Waspalloy have a reputation for being prone to crack on forging, whereas electroslag remelted ingots, which are naturally relatively free from entrained bifilms, forge like butter). It is to be expected therefore that the stainless steel specimens used in this interesting work contain a high density of bifilm defects. The steels would have been essentially precracked with a huge density of randomly oriented cracks. It is no surprise therefore to observe clear bifilm signatures in the fracture surfaces. In particular, Figure 13 illustrates a transgranular fracture mode, typical of environmentally assisted cracking (EAC), but is also a clear example of the folds and creases of an oxide film that had originated on a liquid surface. Figure 15 is even more fascinating, revealing both planar and folded areas, which the authors suggest correspond to austenite and ferrite grains. Planar facets are commonly associated with bifilms that have been pushed by advancing dendrites to create crystallographically flat cracks. If this identification of phase is accurate, in this case, it seems that the close-packed austenite pushes the oxide films effectively, forming planar cracks, whereas ferrite is not so effective. Figure 16 shows characteristic traces of bifilms from the EAC area continuing without a break into the ductile final fracture (DFF) area. Figure 18 illustrates a region of intergranular fracture again typical of that created by bifilms that have been pushed by the advancing solidification front into intergranular regions. Such planar intergranular fractures have been identified in turbulently cast but not in Ni-base alloys and steels that have been carefully cast to avoid turbulent entrainment of the liquid surface. It seems therefore that the authors may have been witnessing in their stress corrosion fatigue testing the advance of corrodant into the pre-existing cracks provided by bifilms. The advance of the initial fatigue crack is rather lengthy, explaining the substantial oxides built up on this portion of the fracture. In contrast, the EAC region had relatively small oxides (the authors have not identified nor suspected the presence of the original bifilm oxide, extending over the entire region, which is probably only nanometers thick, so that the metallurgical structure is seen through the film) as a result of the crack progressing rapidly through the EAC region. Clearly, the DFF region had few if any observable oxides.

Effect of Free-cutting Additives on Machining Characteristics of Austenitic Stainless Steels

The machinability tests were conducted by using a YD-21 dynamometer on a CA6161A lathe. The experiments were conducted to determine the effect of free-cutting additives on machining characteristics of austenitic stainless steels. The conventional austenitic stainless steel 1Cr18Ni9Ti (steel A) and the free cutting austenitic stainless steel (steel B) were prepared. The results have shown that machinable inclusions were composed of MnS and CuO, and they might be also Ti4C2S2. The presence of Bi in the inclusion was detected by the atom map and electro-probe microanalysis (EPMA), which might be one of the most important factors to improve the machinability of austenitic stainless steels. The cutting forces for steel B were lower than those of steel A at various cutting speeds; the abrasion depth of the flank of the tool for steel B was less than that of the steel A under the same cutting conditions. The machinability of austenitic stainless steel was visibly improved by adding free-cutting additives, such as S, Cu and Bi. Ultimate tensile, yield strength, and total elongation values of the free cutting austenitic stainless steel were improved due to the addition of these free-cutting additives.

オーステナイト系ステンレス鋼の0.9wt%食塩水中における疲労特性におよぼす溶存酸素の影響

Fatigue life evaluations in low dissolved oxygen conditions have been found to be conservative regarding the prediction of the fatigue strength of biomaterials. However, dissolved oxygen is considered to increase crack propagation rates. It is necessary to observe whether the strength in low dissolved oxygen conditions is higher. In this paper, the authors observed the effects of dissolved gas on the corrosion fatigue characteristics of austenitic stainless steels. Fatigue strength was higher with low dissolved O2 NaCl aq at a stress ratio of R= 0.1. However, fatigue strength did not change with low dissolved O2 NaCl aq at a stress ratio of R= 0.5 because of the effect of work hardening. Cycles to crack initiation were longer and crack growth rates were lower in the low dissolved O2 NaCl aq. The mechanism of decreasing fatigue strength can be explained by the oxidation process during slipping. In conclusion, dissolved oxygen has the effect of accelerating crack propagation processes.

Erratum to: Microstructural and Stress Corrosion Cracking Characteristics of Austenitic Stainless Steels Containing Silicon

Austenitic stainless steels (SSs) core internal components in nuclear light water reactors (LWRs) are susceptible to irradiation-assisted stress corrosion cracking (IASCC). One of the effects of irradiation is the hardening of the SS and a change in the dislocation distribution in the alloy. Irradiation may also alter the local chemistry of the austenitic alloys; for example, silicon may segregate and chromium may deplete at the grain boundaries. The segregation or depletion phenomena at near-grain boundaries may enhance the susceptibility of these alloys to environmentally assisted cracking (EAC). The objective of the present work was to perform laboratory tests in order to better understand the role of Si in the microstructure, properties, electrochemical behavior, and susceptibility to EAC of austenitic SSs. Type 304 SS can dissolve up to 2 pct Si in the bulk while maintaining a single austenite microstructure. Stainless steels containing 12 pct Cr can dissolve up to 5 pct bulk Si while maintaining an austenite structure. The crack growth rate (CGR) results are not conclusive about the effect of the bulk concentration of Si on the EAC behavior of SSs.