Nickel Stainless Steel Research Articles

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.

ATI 303

Abstract ATI 303 is a free-machining stainless steel specifically designed to exhibit improved machinability. It is the free-machining modification of the basic 18% chromium-8% nickel stainless steel. Sulfur is added to produce the free-machining characteristics. The good mechanical and corrosion-resistant properties of the lower-sulfur grade are retained to the extent possible. This datasheet provides information on composition, physical properties, and tensile properties. It also includes information on corrosion resistance as well as forming, heat treating, machining, and joining. Filing Code: SS-1361. Producer or source: ATI.

Study on fusion boundary microstructure and mechanical properties of austenitic stainless steel-nickel based dissimilar alloy materials welded joints

The metallographic test, microhardness test, and shear punch test of overlayer joint were carried out. The microstructure distribution and micro-zone mechanical properties of overlayer-girth weld fusion boundary (O-G), overlayer-austenitic (O-A) fusion boundary, and austenitic-grith weld fusion boundary (A-G) were studied respectively. At the same time, the type II boundary, DDC, and liquefaction crack were discovered. The results show that the microstructures on both sides of the O-G fusion boundary are γ phase and austenite-ferrite, respectively. There are three types of fusion limitations: type II boundary, direct fusion boundary, and transition fusion boundary. There are DDCs in the transition fusion boundary of the O-G zone, and liquefaction cracks caused by composition segregation in the inner of overlayer. The microstructures on both sides of the O-A fusion boundary are γ phase and uniaxial austenite, respectively, and there is no evident transition zone. Microstructures on both sides of the A-G fusion boundary are equiaxed austenite and austenite-ferrite (lath-skeleton-short rod). The average microhardness and shear strength of the O-A-G fusion border overlayer is the highest, 241 HV and 782 MPa respectively, and the microhardness decreases to 215 HV at DDCs defect. The microhardness and shear strength of base metal are 212 HV, 661 MPa, respectively. The microhardness and shear strength of the girth weld are 192 HV, 600 MPa, respectively. The maximum shear work of O zone is 1.62 J, and the minimum O-G fusion boundary is 1.12 J.

Numerical investigation on transient and steady phase change heat transfer in the evaporator of a loop heat pipe

The dynamic evolution of vapor-liquid distribution in a porous wick coupled with the heat conduction in the evaporator casing of a loop heat pipe is numerically solved. The mathematical model is validated based on the experimental results issued from the literature. Both the transient and steady-state thermal behaviors of the evaporator are focused on, with the self-adjusting ability, evaporator temperature, thermal resistance, and parasitic heat leakage analysis as the evaluation indexes. The gradual invasion of the vapor region into the wick over time and the robust response of the evaporator temperature to varying heat loads are tracked. Additionally, the steady-state performance is explored to optimize the structural parameters, namely, the location of grooves, wick material and porosity, casing material, and fin ratio, through which the specific influences of each parameter are figured out. It is found that locating grooves in wick yields a 7.63°C lower evaporator temperature and a more uniform temperature distribution on the evaporator with a difference of 0.75°C than in casing at 140 W. Additionally, a 0.9 mm thick nickel layer with a porosity of 0.4 combined with a 4.1 mm nickel stainless steel layer with a porosity of 0.75 constitutes an optimized layered wick, which exhibits a 7.04°C lower evaporator temperature and a 0.05°C/W smaller thermal resistance than a single-structured stainless steel wick with a porosity of 0.75. Considering the heat transfer and flow pressure drop, the counterbalanced fin ratio range of 0.5~0.6 and the better thermal performance of copper casing are identified. The numerical results are expected to provide references for the evaporator structure optimization, laying a solid foundation for applying loop heat pipes to thermal control fields.

DOSIMETRY MODELING AND EXPERIMENTAL VALIDATION FOR THE PETALE PROGRAM IN THE CROCUS REACTOR

The PETALE experimental program in the CROCUS reactor intends to provide integral measurements on reactivity worth and dosimetry measurement to constrain nuclear data relative to stainless steel heavy reflectors. The experimental setup consists in eight successive plates of pure iron, pure nickel, pure chromium, or nuclear-grade stainless steel set at the close periphery of the core. The plates are interleaved with up to nine dosimeters that consist of thin activation foils with different possible materials to be sensitive to different ranges of the neutron spectrum. A precise measurement with a good estimation of the uncertainties and correlations is required, especially when comparing reaction rates, e.g. transmission measurement and/or spectral indices. The present work focuses on the validation of the dosimetry technics developed in preparation of this experimental program. Different aspects are discussed: monitors, efficiency calibration, self-absorption correction, self-shielding and nuclear data uncertainties. The different sources of uncertainties for the experiment-calculation comparisons are characterized, taking into account all the correlation between the different dosimeters. These correlations are a mandatory element for the aimed Bayesian assimilation in order to avoir overfitting when considering dosimeter providing a similar information.

Comparison of friction coefficient and surface roughness on stainless steel nickel titanium, and nickel-titanium copper wires to standard edgewise brackets: An experimental in vitro study

Aim: The aim of this study was to investigate the friction and the difference in the roughness of the wire on the standard edgewise bracket. Materials and Methods: This was an experimental laboratory study with a posttest only control group design. The number of samples in this research was 21. The samples were divided into three groups (n = 7) consisting of 0.016′′ x 0.022′′ stainless steel archwire (SS group), 0.016′′ x 0.022′′ nickel-titanium archwire (NiTi group), and 0.016′′ x 0.022′′ nickel-titanium copper archwire (NiTiCu group). The bracket used in each group is standard edgewise slot 0.018. Friction coefficient test was conducted by creating an examination tool from acrylic to fixate the bracket with a size of 2cm x 5cm. The bracket was then attached using glue (polyvinyl acetate) and the archwire was fixated to the bracket using power O. After the friction test, three samples were taken from each group to be tested morphology and topography of each type using scanning electron microscope (SEM). Statistical analysis used in this research is using one-way analysis of variance (ANOVA) to find out the comparison of variables and Tukey’s honest significant difference (HSD) to find out the comparison between three groups (P < 0.05). Results: The lowest friction coefficient was found in SS archwire, which consecutively followed by NiTiCu and NiTi. The smoothest archwire surface observed by SEM was SS, followed by NiTiCu and NiTi. Conclusion: SS wire has the smoothest archwire surface and the lowest frictional force, so it is well used for the teeth movement in space closing on edgewise bracket.

Sintering Problems during Preparation of Ti-Al-Si Alloys

Ti-Al-Si alloys are materials for high-temperature applications. They are characterized by low density, good mechanical properties and excellent resistance against oxidation in comparison with other commonly used alloys, for example nickel alloys or stainless steels. The preparation of Ti-Al-Si is very problematic due to high melting points of the intermediary phases, the high reactivity of melt with the melting crucibles and with the atmosphere in the furnace or formation of the cracks and pores during the process. Powder metallurgy seems to be a promising method for preparation of Ti-Al-Si alloys but there are still many complications. In this work, Ti-Al-Si alloys were prepared by unconventional powder metallurgy techniques and the aim of this work was to describe the problems during the sintering of these materials and their solution.

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.

Status of nickel free stainless steel in biomedical field: A review of last 10 years and what else can be done

The area of biomaterials is a continuous research area. Among others, stainless steels are also used in medical applications such as fracture plates, wires, sutures and implants etc. Surgical grade 316 L stainless steel is specifically used for medical application. It primarily contains nickel, chromium and molybdenum wherein the purpose of nickel is to retain the FCC structure of stainless steel almost at any temperature unlike conventional steel which has ferrite (BCC structure) in ambient temperature. Also, nickel imparts a polished and glossy finish to surgical grade stainless steel which is an important factor to keep it hygienic. But, the harmful effect of nickel on human body has been investigated and reported for quite some time now. The adverse effect of nickel (Ni) ions that release from stainless steel upon crevice and pitting corrosion has led to the evolution of Ni-free stainless steel with high nitrogen content. This paper briefly reviews the effect of nickel release in human body and let go the presence of nickel in stainless steel by uplifting nitrogen content in it. Furthermore, the groundbreaking findings on Ni-free stainless steel in last 10 years are presented and the possibilities of further developments have been hypothesized.

Properties of Novel High Temperature Titanium Alloys for Aerospace Applications

The attractive combination of strength and low density has resulted in titanium alloys covering 15 to 25% of the weight of a modern jet engine, with titanium currently being used in fan, compressor and nozzle components. Typically, titanium alloys used in jet engine applications are selected from the group of near alpha and alpha-beta titanium alloys, which exhibit superior elevated temperature strength, creep resistance and fatigue life compared to typical titanium alloys such as Ti-6Al-4V. Legacy titanium alloys for elevated temperature jet engine applications include Ti-5Al-2Sn-2Zr-4Mo-4Cr, Ti-6Al-2Sn-4Zr-2Mo-0.1Si and Ti-4Al-4Mo-2Sn-0.5Si. Improving the mechanical behavior of these alloys enables improved component performance, which is crucial to advancing jet engine performance. As a world leader in supplying advanced alloys of titanium, nickel, cobalt, and specialty stainless steels, ATI is developing new titanium alloys with improved elevated temperature properties. These improved properties derive from precipitation of secondary intermetallics in alpha-beta titanium alloys. ATI has developed several new alpha-beta titanium alloy compositions which exhibit significantly improved elevated temperature strength and creep resistance. This paper will focus on the effects of chemistry and heat treat conditions on the microstructure and resulting elevated temperature properties of these new aerospace titanium alloys.

Microstructure-Property Relationships in Cold Rollable, High-Strength α/β Alloys

For decades Ti-6Al-4V has been the workhorse alloy for aerospace sheet applications due to its good balance of properties and the known ability to hot roll it with relative ease. Sheet of Ti-6Al-4V is made by hot pack rolling, which is a costly and time consuming process, due to the alloy having insufficient room-temperature workability to support significant cold reduction or forming. Consequentially, Ti-6Al-4V is not typically offered in foil gauges, since the direct product of hot pack rolling contains an undesirable surface finish and insufficient gauge control. Hot pack rolling also limits the maximum sheet size and annual capacity. As a world leader in advanced sheet alloys of titanium, nickel, cobalt, and specialty stainless steels, ATI is developing new titanium alloys with improved strength compared to Ti-6Al-4V that take advantage of a recent understanding of cold workability in high-strength alpha-beta titanium. These α+β alloys exceed Ti-6Al-4V strength while being highly cold formable. Cold rolling via coil processing also enables longer lengths of sheet with significantly improved gauge control and surface finish. Results from pilot scale ingots will be presented upon, including final properties of these unique alloys and microstructure-property correlations developed through modelling.

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.

Cr(VI) Ion Reduction Reaction on Nickel and Stainless Steel Electrodes in Acid Medium

The reduction of Cr(VI) ion in 0.5 M H2SO4 deaerated solutions with different concentrations of K2CrO4 on nickel and 18Cr-10Ni stainless steel electrodes have been studied by potentiostatic polarisation technique depending on the chromate concentration in solution. The kinetic parameters -Tafel slope, charge transfer coefficient and limiting current density -were evaluated comparatively. For the solutions containing �5 mM K2CrO4 the Tafel slopes are higher on stainless steel than on nickel (around -135 mV�dec-1 for nickel and -165 mV�dec-1 for stainless steel). Moreover, by increasing the chromate concentration the Tafel slopes increase on nickel and decrease on stainless steel. The low Tafel slope values of -75 mV�dec-1 obtained on stainless steel electrode in the potential region -0.5� -0.75V vs. SCE could be due to a decrease of the charge transfer process rate because of the presence of a physical barrier. The values for the reaction rates are slightly higher for nickel than for stainless steel electrodes on all the studied potential range. The reaction product is soluble trivalent chromium, excepting the solution with 500 mM K2CrO4, when a Cr(OH)3 film may cover the electrode surface that determines the decrease of the reaction rate.

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.

Structural changes during the formation of diffusion bonded joints between titanium and stainless steel

.In the present investigation, transient liquid-phase bonding was performed between pure titanium (Grade 2) and stainless steel (X5CrNi 18-10) using nickel foil as an intermediate material. The process was carried out at the temperatures of: 950, 975 and 1000 ° C for 60 minutes under the compressive stress of 2 MPa in a vacuum. The microstructure was investigated using light microscopy and scanning electron microscopy equipped EDS. The metallographic examination shows that the diffusion interfaces are free from cracks. However, Kirkendall voids were observed at the borders of materials. Especially large voids were formed in middle section of the joint prepared using the highest bonding temperature. The structure of the joints on the titanium side was composed of the eutectoid mixture αTi+Ti2Ni and layers of intermetallic phases Ti2Ni, TiNi and TiNi3. The nickel interlayer blocked the diffusion of titanium to stainless steel side at 950 °C bonding temperature and prevented from formation of the Fe-Ti intermetallic layers. The layer of a solid solution γFe+Ni between nickel and stainless steel was observed at the 950 °C processing temperature. The mixture of λ+FeTi+Ti, FeTi+Ti, λ+αFe and λ+χ+αFe phases was formed at 975 and 1000 °C at the nickel-stainless steel interlayer.

INVESTIGATION OF CHARACTERISTICS OF SPECIAL POWDERS AND MATERIALS PRODUCED BY MEANS OF SELECTIVE LASER MELTING

The article presents the results of characterization of special powders of metal alloys and materials produced from these powders by selective laser melting (SLM), including comparative analysis of powders produced using VIGA technology. It is noted the importance of a complex study that includes not only a statistical evaluation of particle size distribution of the powders (preferably, by the method of laser diffraction), but also image analysis providing information on the particles’ shape influencing the powders’ flowability. It is shown that the size distribution and shape metrics for nickel refractory alloys and stainless steel powders obtained at the Powder Metallurgy Institute of the National Academy of Sciences of Belarus are at the level of the best foreign analogues. The influence of powder chemical composition on the mechanical properties of SLM samples is considered. The presence of oxygen and undesirable impurities, as a rule, decreases the strength and tensile strain. It is noted that SLM provides extremely wide opportunities for the formation of complex geometric structures with close to full density. Subsequent thermal or thermal and mechanical processing allows reduction of stresses arising during the SLM, densification of products (if necessary) and regulation of their structure and properties. The prospects of applying the backscattered electron diffraction (EBSD) for analysis of the material structure evolution during SLM and subsequent processing are shown. It is noted that products obtained by the SLM from the powders of special alloys exhibit mechanical properties at a level, and in some cases even exceeding the properties of these alloys produced by traditional and other additive technologies.

The evaluation of electromagnetic shielding properties of CFRP/metal mesh hybrid woven laminated composites

Carbon fiber-reinforced plastic (CFRP) composites, owing to their lightweight and strength-weight ratio, are being used in many applications to replace traditional metallic materials and their alloys. The combination of polymeric composites with metallic materials can provide a significant impact in engineering applications. This paper evaluates electromagnetic interference shielding of bimetal-carbon prepreg fibers textile composite materials. Prepreg carbon fibers and metal wire mesh are used to make electromagnetic interference shielding samples. The material samples consist of making plain weaves of metal wire mesh and carbon prepreg and stack them with prepreg carbon fiber layers. In order to produce plain woven fabrics, wefts were made of prepreg carbon fibers and warps were made of wire meshes. In each woven fabric, two yarns of different metal wire meshes were alternated one after another. The combination of conductive wire meshes such as stainless steel-copper, stainless steel-nickel, and copper-nickel in a woven fabric was considered. The electromagnetic shielding effectiveness was evaluated for each textile composite material based on ASTM 4935-99. Results showed a possible application of these materials for electromagnetic interference shielding with higher absorption. The best electromagnetic interference shielding performance was obtained for a combination of stainless steel-copper-CFRP with a shielding effectiveness of 131.6 dB. The absorption losses for all samples were about 82% of electromagnetic interference shielding effectiveness. The mechanical properties and scanning electron image of fabricated samples were also investigated.