Austenitic Stainless Steel Substrate Research Articles

On processing of Ni-Cr3C2 based functionally graded clads through microwave heating

In the current study, functionally graded clads (FGC) of Ni-Cr3C2 based composite powders with varying percentage of Cr3C2 (0%–30% by weight) were developed on austenitic stainless steel (SS-304) substrate through microwave hybrid heating method. A domestic microwave oven working at 2.45 GHz and variable power level of 180–900 W was used to conduct the experimental trials. The exposure time was varied with compositional gradient and was optimized. Scanning electron microscopic (SEM) image of the FGC shows the uniform distribution of Cr3C2 particles inside the Ni matrix. Presence of Ni3C, Ni3Si, Ni3Cr2, and Cr3C2 phases was observed in the different layers of FGC. The top FGC layer exhibits the maximum value of microhardness of order 576 ± 25 HV which was 2.5 times more than that of the substrate.

Effect of firing temperature on microstructure and dielectric properties of chromium oxide based glass composite thick films on stainless steel substrate

We report the influence of firing temperature on Al2O3–chromium oxide based (Cr2O3–Bi2O3–B2O3–SiO2–Al2O3) glass composite (named as GC-1 composite) thick films of thickness (27 ± 3) µm deposited onto 0.6 mm thick austenitic grade stainless steel (DIN 1.4301/AISI 304) substrate by screen printing technique, which can be used as a substitute to alumina substrate. Prior to formulation of glass composite, the chromium oxide based glass (named as GC-1) phase was prepared separately by melt-quench technique. X-ray diffraction analysis confirmed amorphous nature of the GC-1 glass. The thermo gravimetric analysis and differential scanning calorimetry of the GC-1 glass shows thermal stability over the temperature range of 20–1000 °C. We observed that the firing temperature significantly influences microstructural and dielectric properties of the GC-1 composite film. The deposited GC-1 composite films onto stainless steel base were fired at temperatures between the range of 550–750 °C, showed the surface resistivity in the range of (1.0–6.9 ± 0.2) × 1012 ohms per square. The microstructure of these composite films recorded using scanning electron microscopy and electrical properties recorded using LCR meter were correlated with each other. The study revealed that the film fired at 600 °C were found to be superior among the samples under investigation in terms of microstructure, stable relative permittivity [36 (± 1)] and low loss tangent [0.02 (± 0.002)] in frequency range of 1–200 kHz, and surface resistivity (~ 5.1 × 1012 ohms per square).

Evaluation and Control of Mechanical Degradation of Austenitic Stainless 310S Steel Substrate During Coated Superconductor Processing

The superconductor industry considers cold-rolled austenitic stainless 310S steel a less expensive substitute for Hastelloy X as a substrate for coated superconductor. However, the mechanical properties of cold-rolled 310S substrate degrade significantly in the superconductor deposition process. To overcome this, we applied hot rolling at 900 °C (or 1000 °C) to the 310S substrate. To check the property changes, a simulated annealing condition equivalent to that used in manufacturing was determined and applied. The effects of the hot rolling on the substrate were evaluated by analyzing its physical properties and texture.

Processing of Ni20WC10Mo based composite clads on austenitic stainless steel through microwave hybrid heating

In the present investigation, Ni20WC10Mo based composite clads were developed on austenitic stainless steel substrate through microwave hybrid heating technique. Experiments were performed inside a domestic microwave oven working at 900 W and 2.45 GHz. The microwave exposure time at 900 W power was optimized and it was 330 s. Further, the microwave processed clads were characterized through SEM/EDS, XRD, and measurement of Vicker’s microhardness. SEM results revealed that composite clads were free from any type of visible cracks and porosity. The presence of different carbides phases was observed during XRD study of the clad regions. The average Vicker’s microhardness of the clad region was approximately 2.5 times that of SS-316 L substrate.

Mechanical and microstructural characterization of MCrAlY coatings produced by laser cladding: The influence of the Ni, Co and Al content

Laser metal deposition (LMD) and laser cladding (LC) are alternative methods to thermal spraying processes to produce dense, high-quality coatings. In this work, two MCrAlY coatings (M = Ni + Co) have been prepared onto stainless steel substrate using a coaxial LC technique under two different Ni/Co and Al proportions. The mechanical properties were then evaluated with microhardness, nanoindentation, and three-point bending tests. The microstructure and composition of coatings were characterized by X-ray Diffraction (XRD) analysis and Field Emission Electron Microscopy (FESEM) coupled to an Energy Dispersive Spectroscopy (EDS) detector. The study revealed that the γ/β phases formed in the MCrAlY coating microstructure result in a lower elastic modulus than the austenitic stainless steel substrate, while an inverse behavior for hardness was observed due the presence of the aluminum-rich β-phase. Under flexural loads, the failure of coatings showed plasticity and anisotropy characteristics depending on the two laser tracks orientations evaluated.

Effects of 316SS addition on the properties of the coatings based on Al2O3 applied by plasma spraying

Ceramic plasma-sprayed coatings are successfully used for prolonging the service life of industrial components where high wear and corrosion resistance are required. In this work, various types of coatings based on alumina were deposited by atmospheric plasma spraying on 304 L austenitic stainless steel substrate. These coatings were used in further tribological studies. For the atmospheric plasma spraying applications, spraying parameter choices such as carrier gases, plasma enthalpy, current intensity, spraying distance, and particles granulometry are the key issues. Two kinds of Al2O3 particle sizes 2–12 µm (Amperit) and 15–45 µm (Norton) were used to prepare pure and composite coatings. The spraying distance was varied from 90 mm to 120 mm. Microstructure characterization performed by scanning electron microscopy showed that the Amperit powders projected at a distance of 90 mm provided better cohesion and a more dense microstructure. However, the choice of the spraying distance of 120 mm was defined to manufacture composite structures, which allowed more stability in the plasma jet and enabled large metal particles to be mixed with ceramics. To develop hard and wear-resistant coatings, alumina and 316SS were mixed with different addition rates by volume (Al2O3–5 vol.%316SS and Al2O3–25 vol.%316SS) and fed through a single injection port. Composite coatings include porosity and unmolten particles in a lamellar microstructure. The addition of 316SS powder led to the formation of typical layered structure due to the effect of viscosity and different densities of the two particles. These coatings were investigated by different tests to evaluate microhardness, cohesion, and fracture values of such materials. Despite the significant decrease in the microhardness values, the 316SS particle addition demonstrates an improvement in the toughness and crack resistance.

A comparison between destructive and non-destructive techniques in determining coating thickness

Measuring coating thickness is an important part in research works related to coating applications. In general, techniques for measuring coating thickness may be divided into destructive and non-destructive methods which are commonly used depending on the applications. The objective of this study is to compare two methods measuring the coating thickness of electroplating copper coating on the austenitic stainless-steel substrate. The electroplating was carried out in a solution containing 200 g/L CuSO4, 100 g/L H2SO4 at room temperature and current of 40mA/cm2 during 20, 40, 60, 80 and 100 mins as coating periods. And the coating thickness was measured by two methods, cross sectional analysis as a destructive technique and weight gain as a non-destructive technique. The results show that at 20 mins coating time interval, the thickness measured by cross sectional method was 16.67 μm and by weight gain method was 17.37 μm, with difference of 0.7 μm and percentage error of 4.11%. This error increased to 5.27% at 100mins time interval, where the values of the thickness measured by cross sectional and weight gain were 86.33 μm and 81.9 μm respectively, and the difference was 4.43 μm. Moreover, though the weight gain method is fast and gives the indication for the termination of a coating process, information regarding the uniformity, porosity and the presence of cracks cannot be obtained. On the other hand, determining the coating thickness using destructive method will damage the sample.

Effect of Laser Hardfacing Process Parameters on Microstructural Characteristics and Microhardness of Ni–Cr–B–Si–C Deposit on Austenitic Stainless Steel Substrate

Effect of Laser Hardfacing Process Parameters on Microstructural Characteristics and Microhardness of Ni–Cr–B–Si–C Deposit on Austenitic Stainless Steel Substrate

An approach for developing nickel–alumina powder-based metal matrix composite cladding on SS-304 substrate through microwave heating

In the present study, metal matrix composite clads of nickel–alumina powder-based material have been produced on austenitic stainless steel (SS-304) substrate using microwave heating at 2.45 GHz frequency. A concept of hybrid heating was used to process metal matrix composite clads at exposure power level of 900 W. The exposure time for developing metal matrix composite clads was varied from 60 to 300 s. The clads of average thickness 0.6 mm were successfully developed at an optimized exposure time of 300 s. The microstructural analysis of microwave processed clads reveals the uniform dispersion of alumina powder particles inside nickel matrix. The developed clads were free from any type of interfacial cracks and were metallurgically bonded with SS-304 substrate. X-ray diffraction study confirmed the presence of alumina powder, FeNi3 and chromium carbide phases, which contributed to the increase in micro-hardness of developed clad. Clad micro-hardness was found to be four times that of austenitic stainless steel, which makes it suitable for anti-wear applications.

Toplotna obdelava kemijsko nanešene plasti Ni-P na podlagi iz avstenitnega nerjavnega jekla

Toplotna obdelava kemijsko nanešene plasti Ni-P na podlagi iz avstenitnega nerjavnega jekla

Microstructure of reactive magnetron sputtered S-phase coatings with a diffusion sub-layer

The main objective of the work was to investigate the microstructure of S-phase coatings obtained by reactive magnetron sputtering at different temperatures and with various nitrogen concentrations in the working atmosphere. Particular attention was paid to the formation of a diffusion sub-layer in the austenitic substrate. The coatings were deposited on austenitic stainless steel substrates in an argon–nitrogen gas mixture. Three different nitrogen concentrations in the working gas were used in the experiments (15, 33 and 50 vol.%), and five substrate temperatures (200, 250, 300, 350 and 400 °C). The phase composition was evaluated using X-ray diffraction (XRD). X-ray microanalysis (WDS) and glow discharge emission spectroscopy (GDOES) techniques were used to study the nitrogen content and distribution in the coatings. The microstructure was investigated using a scanning electron microscope (SEM). Formation of the S-phase diffusion sub-layers was observed in the atmospheres containing 50 and 33 vol.% N2 respectively at temperatures of 300 and 350 °C or higher. Nitrogen diffusion into the substrate also occurred with the 15 vol% N2 atmosphere at 350 °C or higher although no supersaturated solution was formed in these conditions.

Modelling and Optimization of Copper Electroplating Adhesion Strength

In this paper, Response surface methodology (RSM) was utilized to design the experiments at the settings of CuSO4 and H2SO4 concentrations and current densities. It also used for modelling and optimize the parameters on the adhesion strength of austenitic stainless steel substrate. The adhesion strength was investigated by the Teer ST-30 tester, and the structure of the samples investigated by using scanning electron microscopy (SEM). The modelling approach adopted in the present investigation can be used to predict the adhesion strength of the copper coatings on stainless steel substrate of electroplating parameters in ranges of CuSO4 100 to 200 g / L, H2SO4 100 to 200 g / L and current density 40 to 80 mA / cm2. The results showed that, operating condition should be controlled at 200 g/L CuSO4, 100 g/L H2SO4 and 80 mA/cm2, to obtain the maximum adhesion strength 10N.

An approach for functionally graded cladding of composite material on austenitic stainless steel substrate through microwave heating

In the present work, functionally graded clads of Ni-SiC material have been developed on austenitic stainless steel (SS-304) substrate through 2.45 GHZ domestic microwave applicator. The functionally graded clads were processed by the concept of hybrid heating with varying exposed microwave power levels from 180 to 900 W. The optimum exposure time of 900 W microwave power was varied with compositional gradient and it is from 300 s to 420 s. The maximum thickness achieved for functionally graded clads was 2 mm at optimum exposure power and time. The microstructural analysis of developed clads reveals that the partial mutual diffusion between each successive layer took place and it confirms the metallurgical bonding in between. The typical flower like structure of Ni-matrix has been observed in clads where the SiC particles were uniformly dispersed. The maximum functionally graded clads micro-hardness of 1020 ± 30 HV were achieved.

Evaluation of the Effects of Copper Electroplating Parameters on the Adhesion Using Response Surface Methodology

In this paper, response surface methodology (RSM) was utilized for the experiment design of CuSO4 and H2SO4 concentrations and current densities. RSM was also used to evaluate the significance of each parameter and its interaction on the adhesion strength of austenitic stainless steel substrate. Adhesion strength was investigated by a Teer ST-30 tester, and the structure of the samples investigated by using scanning electron microscopy (SEM). Results showed that increasing the concentration of CuSO4 and decreasing theat of H2SO4 strengthens adhesion. Conversely, the current density only has a slight effect.

Adhesivity of electroless Ni-P layer on austenitic stainless steel

Purpose: Optimization of testing of adhesivity of electroless deposited nickel-phosphorous coatings on austenitic stainless steel substrate. Design/methodology/approach: The main study has been focused on comparison of testing methods of adhesivity of electroless nickel- phosphorous coatings and analyses of influence of heat treatment on adhesivity of electroless nickel- phosphorous. Findings: It was found out that adhesivity of electroless nickel- phosphorous coatings can be successfully characterized by Vickers hardness tester. Research limitations/implications: The study was not extended to other types of deposited layers in order to be able to bring a general decision about applicability of this method in the testing of adhesivity of deposited layers. Practical implications: Based on experimental results it was found out that heat treated nickel-phosphorous coating have higher microhardness than non-heat treated electroless nickel-phosphorous coatings. High microhardness of heat treated nickel-phosphorous coating is connected with formation of Ni3P phase. Moreover, better adhesivity can be achieved by application of proper activation process before electroless coating. Originality/value: Standard Vickers hardness method was successfully applied in testing of adhesivity of electroless nickel- phosphorous coatings on austenitic stainless steel substrate.

Abrasive and erosive wear behaviour of nanometric WC–12Co microwave clads

The present work examines the abrasive and the erosive wear performance of WC–12Co microwave clads. Cladding of micrometric and nanometric WC–12Co powders was carried out on austenitic stainless steel substrate using microwave hybrid heating technique. The micrometric clads exhibited the presence of skeleton structured carbides uniformly distributed in the metallic matrix. On the other hand, presence of clusters of nanocarbides was observed in the nanometric WC–12Co clads. The average microhardness of the nanometric (1564±53HV) was approximately 1.37 times higher than the micrometric clad (1138±90HV). A dry sand rubber wheel apparatus using silica sand as the abradant was used to evaluate the three body abrasive wear performance of the clads at various loads (30, 60 and 90N). The erosive wear performance of the clads was evaluated at various impact angles (30°, 60° and 90°) using solid particle erosion using alumina as the erodent. Lower binder mean free path, higher microhardness and enhanced carbide volume fraction lead to the higher abrasive and erosive wear resistance of the nanometric WC–12Co clads.

Preparation of ultra-fine grain Ni–Al–WC coating with interlocking bonding on austenitic stainless steel by laser clad and friction stir processing

The ultra-fine structured Ni–Al–WC layer with interlocking bonding was fabricated on austenitic stainless steel by combination of laser clad and friction stir processing (FSP). Laser was initially applied to Ni–Al elemental powder preplaced on the austenitic stainless steel substrate to produce a coating for further processing. The as-received coating was subjected to FSP treatment, processed by a rotary tool rod made of WC–Co alloy, to obtain sample for inspection. Microstructure, phase constitutions, hardness and wear property were investigated by methods of scanning electronic microscopy (SEM) with energy-dispersive X-ray spectroscopy (EDX) microanalysis, and X-ray diffraction (XRD), hardness test alongside with dry sliding wear test. The results show that the severe deformation effect exerted on the specimen resulted in an ultra-fine grain layer of about 100 μm in thickness and grain size of 1–2 μm. Synergy between introduction of WC particles to the deformation layer and deformation strengthening contributes greatly to the increase in hardness and friction resistance. An interlocking bonding between the coating and matrix which significantly improves bonding strength was formed due to the severe deformation effect.

Adhesion of Cr/CrN Multilayers to Steel Substrates

Cr/CrN multilayers with a bilayer period λ = 62 ÷ 1000nm, were investigated. They were deposited by PLD technique on austenitic and ferritic stainless steel substrates. Coating hardness and adhesion to substrates were measured by nanoindentation and scratch testing. Multilayer properties were compared with single Cr and CrN coatings. The 2xCr/CrN and 4xCr/CrN multilayers exhibited hardness slightly lower than the hardness of a single CrN coating, while the critical load of the 4xCr/CrN multilayer, measured in the scratch test, was two times higher than for CrN. Furthermore, the character of coating failure also indicates the higher fracture toughness of multilayers than ceramic ones. The highest scratch resistance of the hardest multilayer with a bilayer period λ = 250nm is extremely interesting. The measured values of the critical loads LC1and LC2of all coatings were higher for harder ferritic than austenitic substrates. However, analysis of scratch track geometry indicated that coating failure occurred under the same deformation of the coating-substrate system, while the higher values of critical load for coatings on ferrite derived from the higher hardness of the substrate.

Production of amorphous and nanocrystalline iron based coatings by electro-spark deposition process

An iron-based alloy electrode with a high glass-forming ability was deposited on an austenitic stainless steel substrate by electro spark deposition at a range of process parameters. Overall, six specimens were coated with different parameters. Field emission scanning electron microscopy (FESEM) microstructural studies and X-ray diffraction (XRD) were conducted on the coated samples. The results showed that the coating structure is amorphous at low total heat input values, but at high values of total heat input, an extremely fine-grained or likely nanocrystalline structure is obtained. Hardness of amorphous coating was measured to be 1300 Vickers, which is similar to the hardness of the same Fe48Cr18Mo7B16C4Nb7 amorphous alloy.

Tribological and Corrosion Behavior of HVOF-Sprayed WC-Co-Based Composite Coatings in Simulated Mine Water Environments

WC-based cermet coatings have been considered as alternative replacements to the more traditional hard chrome plating for improved surface properties. Though these coatings are used in engineering applications requiring superior hardness and improved wear resistance, little is known about their corrosion resistance. In this study, four WC-based composite coatings were deposited onto austenitic stainless steel substrates using high-velocity oxy fuel (HVOF) technology. Wear and potentiodynamic scanning studies in a simulated mine environment were conducted on the coatings. Characterization of the as-received powders, coating structure, composition, and morphology was carried out prior to and after wear studies and corrosion testing using optical microscopy, scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX) elemental analysis. The results showed that the chemical composition of the binder material plays a significant role in influencing the wear and corrosion behavior of HVOF-sprayed WC cermet coatings in an aggressive mine water environment. During wet sliding, addition of Cr in the binder improves the wear resistance of the coating. WC-10Co-4Cr showed the highest wear resistance in a wet sliding environment and also exhibited the best corrosive behavior of the evaluated coatings, due to a Cr2O3 oxide passive film that forms during anodic polarization.