جستجوی مقالات مرتبط با کلیدواژه « فولاد زنگ نزن l316 » در نشریات گروه « مواد و متالورژی »

The purpose of this research is to investigate the change of rotational speed and traverse speed on the microstructure and mechanical properties of the joint in friction stir welding of aluminum 1050 and 316L stainless steel. For this purpose, the microstructure, thickness of intermetallic compounds, hardness and tensile test on the joint were investigated. The proper selection of welding parameters leads to the creation of a joint with suitable metallurgical and mechanical properties. In this research, two rotational speeds of 560 and 900 rpm and four traverse speeds of 60, 80, 100 and 125 mm/min were performed. The microstructure consisted of four areas of the base metal, heat affected zone, thermo-mechanical affected zone and stir zone. In all the samples, the stir zone (SZ) contained a recrystallization microstructure with fine equiaxed grains. According to the Energy dispersive X-ray Spectroscopy results, an IMC layer formed in the joint interface. The hardness of the stir zone in all samples was higher than the aluminum base metal due to the formation of recrystallization fine equiaxed grains and the presence of steel particles. The best sample in terms of mechanical properties, mocrostructure and joint quality was obtained in the conditions of rotation speed of 900 rpm and advance speed of 125 mm/min. The strength was equal to 84 MPa with 77% efficiency.

In this study, the addition of organic methionine inhibitor (as an eco-friendly inhibitor) to 0.1 M sulfuric acid media on corrosion resistance of 316L austenitic stainless steel (fabricated by rolling method and three-dimensional (3D) printing method) was investigated. Open-circuit potential electrochemical test and impedance, and structural tests such as optical and electron microscopy and x-ray photoelectron spectroscopy were conducted. The results showed that the corrosion resistance in the presence of inhibitor was higher than the sample without inhibitor and the inhibitory efficiency of methionine was increased up to 64% and the resistance to surface transfer between metal oxide and electrolyte was improved up to 2.77 times. The addition of methionine reduced the surface roughness and accumulation of the surface cavities. The chemical and physical adsorption mechanism of the inhibitor (negatively charged side adsorption of the methionine molecule with positively charged anodic regions of the metal surface) occurred at all points on the surface of the sample with the inhibitor. Also, the amount of oxygen in the cavities was reduced and the distribution of sulfur was uniform. The thickness of the passivator oxide layers was calculated more than the sample without inhibition due to the addition of inhibitor.

With the advances in the development of biomaterials for tissue replacement, the attention of scientists has been focused on the improvement of clinical implant properties. In this regard, despite the appropriate properties of the stainless steel, the application of stainless steel as implants has been limited due to the weak corrosion resistivity. The purpose of this paper was preparation and characterization of hydrophobic polydimethylsiloxane (PDMS)-SiO2-CuO nanocomposite coating on the 316L stainless steel surface. The 316L stainless steel was coated by SiO2 nanoparticles (20 wt. %), CuO nanoparticles (0.5, 1 and 2 wt. %) and biocompatible PDMS. In this research, x-ray diffraction (XRD) and scanning electron microscopy (SEM) were applied to characterize the coating. Moreover, the roughness and water contact angle of the coatings consisting of various amounts of CuO nanopowder were estimated. Finally, the effects of various amounts of the CuO nanopowder on the corrosion resistivity of nanocomposite coatings were investigated. XRD patterns confirmed the presence of crystalline CuO nanoparticles on the substrate. Due to the non-crystalline nature of silica nanoparticles and the semi-crystalline PDMS polymer, no peak confirming the presence of these phases was detected on the XRD pattern of the nanocomposite coating. SEM images showed the formation of a lotus leaf-like layer on the surface of the nanocomposite coating containing 1 and 2 wt. % CuO. Moreover, water contact angle evolution revealed that while contact angle was 81 degree without CuO nanoparticles, it was enhanced to 146 degree in the presence of 1 wt. % CuO. Moreover, the corrosion study showed the nanocomposite containing 2 wt.% CuO had the best corrosion resistance, the corrosion current density of 2.1E-7 A.cm-2, and the corrosion potential of 0.22 V.

Titania-halloysite nanotubes (HNTs) nanocomposite coatings were electrophoretically deposited on the 316L stainless steel substrate. Two-component suspensions of titania and HNTs particles (different ratios of titania : HNTs wt% and constant particles concentration of 10g/l) in ethanol with 0.5g/l of polyethyleneimine (PEI) as the dispersant were used for electrophoretic deposition (EPD) experiments. EPD was performed at 60V for 10 and 60s using a two-electrode cell. Coatings were sintered in vacuum furnace and at 700˚C for 1h. Microstructural, element mapping and EDX analysis were performed on the coatings using a SEM. It was found that HNTs reinforce the microstructure of coatings and prevent from the cracking of coatings deposited from the suspensions with HNTs>25wt%. The corrosion rate of substrate coated at 10 and 60s using the suspensions with different ratios of titania: HNTs was measured by electrochemical polarization technique in Ringer solution and at 37˚C. The corrosion rate of substrates coated for 60s decreased as the HNTs content increased in the suspension due to the crack-free microstructure of prepared coatings. However, the corrosion rate of substrates coated at 10s increased as the HNTs content increased in the suspensions due to the less packing density and thickness of prepared coatings.

Effect of boriding and borochromizing treatments on microhardness, wear properties and corrosion resistance of austenitic low carbon stainless steel (AISI 316L) has been studied. Coating was applied by using of pack cementation method. The pin on disk test was employed at two loads of 75 and 115N to evaluate the wear behavior of the samples. Corrosion test was performed by using of immersion method in (10 vol.%)HCl and (10 vol.%)H2SO4 acid solutions on uncoated, borided and borochromized specimens.The results reveals that specimen with borochromized coating provides higher surface hardness and more desirable wear behavior in respect to uncoated and borided specimens. Fatigue- oxidation wear mechanism is also found as the main deterioration mechanisms of surface layers in coated specimens. Borochromized specimen has Also higher corrosion resistance in comparision with the borided specimen, although, it has, in some extend, similar corrosion behavior to that of the substrate.