Low Nickel Stainless Steel Research Articles

Optimizing the compression resistance of low-nickel stainless steel coronary stents using finite element and response surface methodology

Considering the high strength and excellent biocompatibility of low-nickel stainless steel, this paper focused on optimizing the design of a vascular stent made from this material using finite element analysis (FEA) combined with the response surface methodology (RSM). The aim is to achieve the desired compressive resistance for the stent while maintaining a thin stent wall thickness. The parameters of the stent’s support unit width (H), strut width (W), and thickness (T) were selected as input parameters, while the output parameters obtained from FEA included the compressive load, the equivalent plastic strain (PEEQ), axial shortening rate, radial recoil rate, and metal coverage rate. The mathematical models of input parameters and output parameters were established by using the Box Behnken design (BBD) of RSM. The model equations were solved under constrained conditions, and the optimal structural parameters, namely H, W, and T, were finally determined as 0.770 mm, 0.100 mm, and 0.075 mm respectively. In this situation, the compression load of the stent reached the target value of 0.38 N/mm; the PEEQ resulting from the stent expansion was small; the axial shortening, radial recoil, and metal coverage index were all minimized within the required range.

Mechanical properties of a novel high nitrogen and low nickel stainless steel S35657

Stainless steel exhibits excellent ductility and corrosion resistance, making it highly promising for applications in civil engineering. In order to investigate the mechanical properties of a novel stainless steel S35657, a total of 150 coupons including 125 plates and 25 rods were tested. The failure modes, stress-strain curves, and mechanical parameters of coupons were obtained. Fractographic analysis using scanning electron microscopy was also performed to investigate the failure mechanisms. It was found that all coupons exhibited ductile failure mode with elongation up to 52.08%. The nominal yield strength standard value reached 370.50 MPa, while the ultimate tensile strength standard value reached 736.07 MPa. The various existing typical constitutive models were assessed, indicating that these models provide a good fit in the elastic stage but are not applicable in the hardening stage. Based on the Ramberg-Osgood model and test results, a new constitutive model applicable to stainless steel S35657 was proposed. Moreover, a design reliability analysis was carried out using the Equivalent Normalization Method (JC method), and partial factors for resistance of stainless steel S35657 were calibrated, which were 1.05 under windless load combinations and 1.15 under windy combinations.

Electrochemical and corrosion protection performance of Sr-HaP/PoPD coated LN stainless steel

BackgroundStainless steel is a common implant material used in orthopaedic surgeries. However, metallic ions are released from the implants when it placed inside the human body. Coating of biocompatible material such as strontium hydroxyapatite (Sr-HaP) is one of the methods to reduce the release of metallic ions into the body. MethodIn the present work, we have developed a bilayer coating namely poly-orthophenylenediamine (PoPD) on Sr-HaP deposited low nickel stainless steel (LNSS) via electrochemical deposition followed by electropolymerization methods. The Sr-HaP/PoPD coating was confirmed with Fourier transform infrared spectroscopy (FTIR) and high resolution scanning electron microscopy (HR-SEM). The corrosion protection performance of the coated LN SS specimens in Ringer's solution was investigated using potentiodynamic polarisation and electrochemical impedance spectroscopic techniques. The leach out characteristics of the coating was determined at the impressed potential. Significant findingsThe studies revealed that the passive film underneath the PoPD layer is acting like a shield and prevent the LN SS from corrosion. Furthermore, the potential bioactivity of LN SS is due to the presence of top porous Sr-HaP layer. Hence, the PoPD/Sr-HaP bilayer coating on LN SS substrate could be a promising material for orthopaedic implant applications.

Dissimilar welding of AISI 201 and 202 low nickel stainless steels by GTA and PA welding processes

This paper presents the results of dissimilar joining techniques for AISI 201 and 202 low nickel austenitic stainless steels. These were welded by Gas Tungsten Arc Welding (GTAW) and Plasma Arc Welding (PAW). The tests were performed to examine the weld bead shapes, microstructure, mechanical properties and corrosive behavior of the weld metals with different welding processes. The weld bead shape by GTAW was larger than that performed by PAW. The microstructure of the weld metal produced by GTAW contained more delta ferrite in the austenite matrix than the weld metal produced by PAW. The volume of hardness in welds produced by PAW higher than the GTAW process same with the ultimate tensile strength and percentage elongation welds produced by PAW higher than the GTAW process. According to the potentiodynamic polarization test results, pitting corrosion resistance of the weld produced by PAW was higher than the weld produced by GTAW. Both weld metals showed the pitted area adjacent to the phase boundary between austenite and delta ferrite in the mixed microstructure. Based on the present work, it was concluded that PAW was the more suitable welding procedure for joining dissimilar 201 and 202 austenitic stainless steels.

Corrosion Performance of 201 low-Nickel Stainless Steel Anchor in Cl– Contaminated Underground Water with Various Concentrations of SO4 2− and HCO3 −

Corrosion behavior of 201 low-nickel stainless steel was studied in Cl−-contaminated underground water with various concentrations of HCO3 − and SO4 2− at different pHs to investigate the durability of stainless-steel anchors. The charge-transfer resistance increased, whereas the carrier densities and corrosion current density decreased with an increase in concentration of HCO3 − and SO4 2−, and solution pH. A parameter that was termed the composite corrosiveness index (CCI) was proposed to assess the corrosivity of underground waters to stainless steels. The CCI exhibited a monotonic relationship with charge-transfer resistance, carrier density, and corrosion current density, and it was more suitable for stainless steels compared with previous corrosiveness indexes in underground waters.

Electrochemical Study of Stainless Steel Anchor Bolt Corrosion Initiation in Corrosive Underground Water

Application of low-nickel stainless steel anchor was one of the economical and effective methods to solve the durability problem of slope engineering. At present, there are scarce reports about corrosion characteristics of low-nickel stainless steel in various underground waters. For investigating the corrosion initiation of stainless steel anchor bolt in corrosive underground water, the effect of SO42−, HCO3− and pH value on the corrosion behavior of 201 low-nickel stainless steel was studied via electrochemical methods. As the SO42− concentration, HCO3− concentration or pH value increase, the open circuit potential and polarization resistance increase, while the double-layer capacitance, donor density and passive current density decrease. The results indicate that corrosion is inhibited by SO42−, HCO3− and OH− in underground water. In addition, the inhibitive efficiency of SO42− and HCO3− increases with the SO42− and HCO3− concentration.

Effect of Heat Input on the Microstructural, Mechanical, and Corrosion Properties of Dissimilar Weldment of Conventional Austenitic Stainless Steel and Low-Nickel Stainless Steel

In the present investigation, an attempt has been made to investigate the replacement compatibility of conventional austenitic stainless steel (316L) with low-Ni austenitic stainless steel (201) by employing their dissimilar welding using gas tungsten arc welding technique with varying heat input. The effects of heat input on the microstructural, mechanical, and corrosion properties were studied. The result depicts the balanced austenite/ferrite content in the fusion zone for both the heat inputs. The low heat input process, which results in a faster cooling rate, demonstrates higher tensile strength and microhardness. Similarly, the pitting corrosion resistance of the fusion zone demonstrates better properties on the low heat input process attributed to the lesser dendritic length and lesser interdendritic arm spacing.

Heat input and shielding gas effects on the microstructure, mechanical properties and pitting corrosion of alternative low cost stainless steel grade 202

The intention of this study was to create information for welders and engineers in regards to 202 (200-series) austenitic grade stainless steel as a low cost alternative for the replacement of 300-series stainless steel. The content of this paper discusses the effects of different heat inputs and different nitrogen mixes in the argon shielding gas using the GTA welding process. This paper discusses the effects to the microstructure, mechanical properties and corrosion resistance of the weld metals. The results of this study indicate that reducing the heat input when welding caused the width of the face and root of the weld bead to be narrower. The microstructure (delta ferrite, dendrite length and interdendrite spacing) tended to decrease and the hardness and ultimate tensile strength tended to rise. In addition, the percentage of elongation decreased while the pitting corrosion resistance increased. An increase of nitrogen in the argon shielding gas did not cause the width of the weld bead to change. However, the volume of delta ferrite, dendrite length and inter-dendrite spacing reduced and the hardness and ultimate tensile strength increased. The percentage of elongation was shown to decrease and the pitting corrosion resistance tended to increase. The test results of this work focused on increasing productivity and reducing the cost of production from the use low nickel stainless steel in the fabrication industries of Southeast Asia.

Study on Preparation and Properties of Resource-Saving Nitrogenous Stainless Steel

In order to alleviate the shortage of global nickel resources, it is imperative to develop low nickel stainless steel. This paper presents a novel approach based on increasing nitrogen and reducing nickel for smelting economical stainless steel. Taking 06Cr19Ni10 stainless steel as the object, the test steels with different nitrogen and nickel content were smelted using vacuum induction furnace (ZG-0.01) under the laboratory conditions, and the effects of alloy content on microstructures, mechanical properties and corrosion properties of the economical stainless steel were investigated. The results show that the microstructure of the tested steel which nitrogen content 0~0.28% and nickel content 5.98~9.63% is still the single austenitic, and the grain size decreases as the nitrogen content increases. Nitrogen deteriorates the impact toughness of the tested steel, and the room temperature impact absorption energy is reduced from 267 J at the nitrogen content of 0 to 228 J at nitrogen content of 0.28%. Rockwell hardness, tensile strength and yield strength increase with the increase of nitrogen content. When the nitrogen content is 0.28%, the optimum mechanical properties of 06Cr19Ni10 steel are obtained. The Rockwell hardness is 95.4 HRB, the tensile strength is 814 MPa, the yield strength is 437 MPa, and the elongation after fracture is 52.5%. The degree of intergranular corrosion of the tested steel is reduced significantly with the increase of nitrogen content, from 0.023 μm to 0.008 μm. The experimental data prove that the composition design concept of increasing nitrogen and reducing nickel is feasible for smelting economical stainless steel.

Enhancement of corrosion protection of low nickel austenitic stainless steel by electroactive polyimide-CuO composites coating in chloride environment

Purpose The purpose of this study is to improve the anticorrosion performance of low nickel stainless steel (AISI 201) in 3.5% NaCl by electroactive polyimide/copper oxide (EPI/CuO) composites coating. Design/methodology/approach Electroactive polyimide/copper oxide (EPI/CuO) composites were prepared by oxidative coupling polymerization followed by thermal imidization method. Findings The functional and structural properties of composites were characterized by X-ray diffraction, Fourier transmission infra-red and ultra violet-visible spectroscopy and the surface topography was characterized by field emission scanning electron microscope analysis and anticorrosion performance in 3.5 Wt.% NaCl was evaluated by electrochemical techniques. The obtained results of electrochemical techniques measurement indicated that the composites coated samples give better corrosion protection against attacking electrolyte. Originality/value The ever-increasing price of nickel (Ni) is driving the industries to use low-Ni austenitic stainless steels (ASSs). However, it exhibits relatively poor corrosion resistance as compared with conventional Cr-Ni ASSs. Nonetheless, its corrosion resistance can be enhanced by polymeric (electroactive polyimide [EPI]) coating. CuO particles exhibit the hydrophobic properties and can be used as inorganic filler to incorporate in EPI to further enhance the corrosion protection. The present research paper is beneficial for industries to use low-cost AISI 201, enhance its corrosion resistance and replace the use of costly conventional Cr-Ni ASSs.

Corrosion behavior of deformed low-nickel stainless steel in groundwater solution

Abstract Effect of deformation on the corrosion behaviour of 201 low-nickel stainless steel in a simulated groundwater solution was studied via electrochemical tests. The open-circuit potential, pitting potential, polarization resistance and the thickness of passive film decreased with the magnitude of deformation. The carry density of passive film significantly increased as the deformation increasing. In general, the deformation shows a negative effect on the corrosion resistance of the low-nickel stainless steel, which causes the stainless steel more susceptive to pitting in the groundwater. Moreover, the number of pitting initially increased with the magnitude of elastic deformation, while the depths of pitting were extended whereas the number of pitting does not be significantly influenced by the increasing plastic deformation.

Microstructure, Mechanical and Electrochemical Evaluation of Dissimilar low Ni SS and 304 SS using Different Filler Materials

This study investigates the effect of dissimilar metal welding of low nickel stainless steel (SS) and 304 SS employing tungsten inert gas (TIG) welding process by using three different filler materials (316L, 308L and 310 SS). Microstructural, mechanical properties and corrosion behavior in 3.5% NaCl solution was studied. The microstructural investigation revealed the formation of δ-ferrite and γ-austenite in the weld (welded by 316L and 308L filler). The Higher δ-ferrite content was found more in 316L weld zone. Whereas samples welded by 310 SS filler showed the columnar structure in the weld zone. Relatively wider heat affected zone (HAZ) was measured on Cr-Mn SS side as compared to 304 SS side. Impact fracture surface of all the welded samples exhibited dimple appearance. Corrosion studies showed better pitting corrosion resistance in 316L SS welded sample due to the beneficial effect of δ-ferrite and also the addition of molybdenum (Mo). Electrochemical impedance spectroscopy (EIS) revealed higher polarization resistance (Rp) in 316L SS as compared to other fillers. Galvanic current density was found to be higher in Cr-Mn SS as compared to 304 SS when coupled with different welded samples.

Degradation of Passive Film on Low-Nickel Stainless Steel in Groundwater with Different Concentration of Chloride Ions

Degradation of Passive Film on Low-Nickel Stainless Steel in Groundwater with Different Concentration of Chloride Ions

Novel copper doped Halloysite Nano Tube/silver-poly(pyrrole-co-3,4-ethylenedioxythiophene) dual layer coatings on low nickel stainless steel for anti-corrosion applications

Abstract The increase of the diverse and complicated applications of stainless steel in all fields of industry production and various research activities have induced immense efforts in research and fabrication to increase its efficiency and sophisticated to minimize its corrosion by using among others conducting polymer coatings. The present work discusses the corrosion resistant behavior of stainless steel with copolymer and composite dual layer coatings. The coated samples were analyzed by various analytical studies and the results are discussed. The dual layer composite coating Ag-p(Py-co-EDOT) thus obtained was uniform in nature and highly adherent to the stainless steel surface, when compared to the monolayer coatings. An antibacterial effect of coating and the coatings against marine and pathogenic bacteria have also been studied.

Electrochemical deposition of a Zn-HNT/p(EDOT-co-EDOP) nanocomposite on LN SS for anti-bacterial and anti-corrosive applications

A copolymer composite of Zn-HNT/p(EDOT-co-EDOP) was deposited on low nickel stainless steel (LN SS) using an electrochemical polymerization method.

Molten Pool Behavior and Mechanical Properties of Pulsed Current Double-Sided Synchronization GTA Welded Fe-18Cr-17Mn-Ni-N

Double-sided synchronization vertical gas tungsten arc welding (DSSVW) procedure was used to weld high-nitrogen low-nickel stainless steel Fe-18Cr-17Mn-Ni-N without groove and filler wire. First, the molten pool behaviors and appearances of pulsed current DSSVW (PC-DSSVW) and constant current DSSVW (CC-DSSVW) were comparatively analyzed. The periodic variation occurs in the width of both the anode region of the arc and the molten pool tail during PC-DSSVW, while the contact angle first increases and then decreases, and both the width of the anode region and the length of arc plume increase progressively in CC-DSSVW. It is found that the weld appearance of PC-DSSVW is superior to that of CC-DSSVW. Second, the forces of the DSSVW molten pool were analyzed. The result indicates that the molten pool of the DSSVW procedure is in a state of unstable equilibrium, and it will easily lose balance after being disturbed, resulting in the asymmetrical weld or hump bead. Third, the PC-DSSVW experiments at various welding speeds were conducted to study the influence of welding speed on the weld profile, microstructure, tensile strength and impact toughness. Furthermore, the solidification mode of Fe-18Cr-17Mn-Ni-N was predicted to help determine the microstructure of the welded joint. Results indicate that the weld width, weld reinforcement and melting area all increase with decreasing welding speed, and Fe-18Cr-17Mn-Ni-N solidifies as A mode. The microstructure of the base metal (BM) and heat-affected zone (HAZ) is equiaxed austenite and that of the fusion zone (FZ) is austenite dendrite with some chromium carbides dispersed in the grain boundary; with decreasing welding speed, grains become coarse. The maximum tensile strength (UTS) and elongation of PC-DSSVW joint are 860 MPa and 8.1%, and the elongation decreases dramatically with decreasing welding speed. The impact toughness decreases substantially compared to the BM, achieving 48.2% of the BM.

Poly(ophenylenediaminecoaniline)/ZnO coated on passivated low nickel stainless steel

Abstract Iron and its alloys are broadly used in many applications, which have strengthened the research in corrosion resistance in various neutral and provoking environments. Almost powerful corrosion inhibitors have negative effects on both environment and health. Therefore, there is a need for a primer that provides outstanding adherence and corrosion resistance, and is environmentally safer. The conducting polymer coating on metals was found to offer the anti-corrosion. In this work, the Poly(o-phenylenediamine-co-aniline) copolymers (P(Popd-co-Ani)) and Poly(o-phenylenediamine-co-aniline)/ZnO (P(Popd-co-Ani)/ZnO) composite were synthesized using the electrochemical techniques on borate passivated low nickel stainless steel (LN SS) electrodes from lithium perchlorate in acetonitrile solutions containing a fixed concentration of monomer and different concentrations of zinc oxide (ZnO). The structural and morphological analyses of the copolymer and composite coatings were conducted by Fourier transform-infrared spectroscopy (FT-IR), X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), elemental mapping and energy dispersion X-ray spectroscopy (EDX). The surface topography was assessed with using an atomic force microscope (AFM), and the corrosion protection behavior of these copolymer-coated stainless steels was investigated in a 0.5 M H 2 SO 4 solution by the potentiodynamic polarization (Tafel) and electrochemical impedance spectroscopy methods. Among the as developed protective copolymer coatings, the P(Popd-co-Ani)/ZnO composite exhibited the best corrosion protection.

Anti-Corrosion Application of Poly(indole-5-carboxylic Acid) Coating on Low Nickel Stainless Steel in Acidic Medium

Anti-Corrosion Application of Poly(indole-5-carboxylic Acid) Coating on Low Nickel Stainless Steel in Acidic Medium

Cyclic Voltammetric Study of the Pitting Corrosion Behavior of Low-Nickel Austenitic Stainless Steels in Citric Acid

The pitting corrosion behavior of AISI 202 stainless steel (SS) – a low-nickel, austenitic SS grade, was investigated by means of cyclic voltammetry (CV) technique complemented by Scanning Electron Microscopy (SEM). From the starting potential, the current density decreases and changes its sign at the corrosion potential (Ecorr). The anodic response exhibits a well-defined anodic peak followed by a passive region. A noticeable increase in the anodic current density was observed after reaching the breakdown potential (Eb). The second anodic peak which may be attributed to onset of oxygen evolution was also observed. Moreover, the cyclic voltammograms revealed that hysteresis loop is absent for all the studied concentrations, indicating that AISI 202 SS in citric acid is highly resistant to pitting corrosion as also supported by the results of SEM. It was found out that the critical current density (icrit) increases with increasing citric acid concentration.

Electrochemical Investigation of the Effects of Acid Concentration and Dissolved Oxygen on the Corrosion Behavior of Austenitic Low-Nickel Stainless Steels in Citric Acid

All materials which are intended to have in contact with food and other commodities produced or processed for human consumption are called food contact materials (FCM’s). Stainless steel (SS) – a widely known metallic FCM is used mainly in processing equipment, containers and household utensils. It is known for having numerous industrial and domestic applications worldwide due to its special characteristics of having notable corrosion resistance. However, this corrosion resistance is not all-encompassing since SS may still undergo degradation when subjected to a specific corrosion-inducing environment. SS may be classified according to its microstructure. If the atoms which make up the SS can be viewed as having a face-centered cubic structure, then the alloy is said to be austenitic. This SS grades include the conventional 300-series and the newly-developed 200-series. The former has superior corrosion resistance while the latter is far cheaper. In this study, the corrosion behavior of AISI 202 SS in two different levels of dissolved oxygen (O2) and three acid concentrations was investigated using electrochemical techniques, namely, open-circuit potential (OCP) measurements and electrochemical impedance spectroscopy (EIS). As the concentration of citric acid is increased, the measured OCP values of the alloy decreased and the polarization resistance (Rp) decreased, indicating decrease in alloy stability and decline in the corrosion resistance, respectively. With regards to effects of dissolved O2, results revealed that increasing the level of dissolved O2 has consequently increased the polarization resistance and shifted the OCP to more positive values. All the generated Nyquist plots exhibited a depressed capacitive loops indicating that corrosion in the designated solution occurred with charge transfer as the rate-determining step.