Papers by Keyword: Stainless Steel (SS)

Abstract: The behavior of Fe-12Cr-2Mo stainless steel exposed isothermally in tube furnace at 700°C for 10 h had been studied in different environments; of mixed environment (Ar-20%O₂ with coated Na₂SO₄-50%NaCl salts), molten salt (Na₂SO₄-50%NaCl) and dry oxygen (Ar-20%O₂) atmospheres. The exposed samples were characterized by using optical microscopy (OM), scanning electron microscope (SEM), energy dispersive X-ray (EDX) and X-ray diffraction (XRD). The results indicated that, sample exposed in mixed environments undergoes highest corrosion rate compared with other samples. The main phase exists in all samples generally were iron-rich oxides which non-protective and thick. Conversely, EDX analysis on cross-sectional samples revealed the Cr-enrichment developed underneath the iron-rich oxide scales as the chromium concentration increases towards near the substrate. In presence of salt mixture, the oxide scales undergo spallation, however there is no crack observed. The catastrophic corrosion sample was occurred in combined environment due to the oxidation induced by the chloridation and sulfidation phenomena as well.

Abstract: Calcium hydroxyapatite (Ca₁₀(PO₄)₆(OH)₂, CHAp), tricalcium phosphate (Ca₃(PO₄)₂, TCP) and calcium oxide (CaO) are the main components of inorganic part of human bones. Such synthetic nanocomposites could be very important implantable materials and using as substitute material for human hard tissues (bones and teeth). In this study, an aqueous sol-gel chemistry route has been developed to prepare nanostructured CHAp thin films on stainless steel substrate. For the preparation of thin films dip-coating and spin-coating techniques were used. The final samples were obtained by calcination of coatings for different time at 1000 °C. For the characterization of surface properties, the X-ray powder diffraction (XRD) analysis, scanning electron microscopy (SEM), atomic force microscopy (AFM) and the contact angle measurements were recorded.

Abstract: The researches in the cutting domain have as purpose the cutting process economic optimization. This paper studies the cutting tool wear at drilling of the stainless steel X15CrNiSi20-12. The experimental data and their subsequent processing represent the original contribution of the authors to the estimation of polytropic exponents and to the assessment in terms of structure of the calculus relation of the cutting tool wear. The obtained relationship of the cutting tool wear on the tool putting surface at drilling of the steel X15CrNiSi20-12 permits the determination of the wear on the putting surface, in the case of a couple: stainless steel X15CrNiSi20-12 - Rp5 high-speed spiral drill, depending on the work parameters and the cutting conditions. Putting the condition of wear limitation, from the obtained relation, the cutting speeds are exactly given. The paper also contains graphs for the variation of the tool wear with parameters of the cutting technology. The results can be taken into consideration in the educational studies and in the theoretical technical research. They can be implemented in the manufacturing activity.

Abstract: This paper studies the cutting force at drilling of the stainless steel X15CrNiSi20-12. The structure of the cutting force relation was modified with respect to the relation available in the technical literature for common steels. The tool speed was included in the calculus relation. The experimental data and their subsequent processing represent the original contributions of the authors to the estimation of polytropic exponents and to the assessment in terms of structure of the calculus relation of the cutting force. The paper also contains graphs for the variation of the cutting force with parameters of the cutting technology. The graphs are drawn based on the analytic relationship of the cutting force, obtained in the paper, using the mathematical software Maple. The results presented in this study can be taken into consideration in the educational studies and in the theoretical technical research. Also, they can be readily implemented in the manufacturing activity. Our further studies aim these problems for another steels classes.

Abstract: This paper studies the cutting moment at widening of the stainless steel X20Cr13. The structure of the cutting moment relation was modified with respect to the relation available in the technical literature for common steels. The tool speed was included in the calculus relation. The experimental data and their subsequent processing represent the original contributions of the authors to the estimation of polytropic exponents and to the assessment in terms of structure of the calculus relation of the cutting moment. The paper also contains graphs for the variation of the cutting moment with parameters of the cutting technology. The graphs are drawn based on the analytic relationship of the cutting moment, obtained in the paper, using the mathematical software Maple. The results presented in this study can be taken into consideration in the educational studies and in the theoretical technical research. Also, they can be readily implemented in the manufacturing activity. Our further studies aim these problems for another steels classes.

Abstract: The researches in the cutting domain have as purpose the cutting process economic optimization. This paper studies the cutting tool wear at drilling of the stainless steel X20Cr13. The experimental data and their subsequent processing represent the original contribution of the authors to the estimation of polytropic exponents and to the assessment in terms of structure of the calculus relation of the cutting tool wear. The obtained relationship of the cutting tool wear on the tool putting surface at drilling of the steel X20Cr13 permits the determination of the wear on the putting surface, in the case of a couple: stainless steel X20Cr13 - Rp5 high-speed spiral drill, depending on the work parameters and the cutting conditions. Putting the condition of wear limitation, from the obtained relation, the cutting speeds are exactly given. The paper also contains graphs for the variation of the tool wear with parameters of the cutting technology. The results can be taken into consideration in the educational studies and in the theoretical technical research. They can be implemented in the manufacturing activity.

Abstract: This paper investigates the laser welding of AISI 304 stainless steel thin sheets. For the experimental procedure a 3,3 kW Nd:Yag laser was used. Nine samples were realised during this study and the influence of the process parameters on to the geometry and microstructure of the weld bead is analysed. The best result in case of 0,5 mm stainless steel laser welding are obtained by using a density power in the range of 700-850 kW/cm² associated with a minimum spot diameter of 0,4 mm. The weld bead compositional content was determined by an X ray dispersive field analyses. A decreasing of Mn and Si content into the weld zone was produced mainly by the burning and vaporization effects during the laser welding. Good tensile behaviour of the joints was obtained at all samples with fracture was produced at 600 MPa.

Abstract: Titanium alloys and stainless steel have been widely used in the production of prostheses, medical and dental devices, due to resistance and anticorrosive properties. Despite that, the values of the elastic modulus of these alloys are about 3-5 times higher than the human bone. So, many researches have sought alternatives to these alloys, in order to obtain alloys with good mechanical strength, low modulus of elasticity and excellent biofunctionality. This work highlights by scientific and technological form, the collection and analysis of the module of elasticity and chemical composition, related to normalizations. The properties obtained, being inadequate, highlights the danger of bone absorption, causing loss of adhesion of the prosthesis and reducing its useful life, In addition, chemical abnormalities are a fundamental problem in terms of risk. Results of this study are shown and analyzed.

Abstract: The arthroplasty is a surgical procedure which is characterized by replacing the defective joint surfaces of biomaterials intended to restore the function of these joints. As soon because the relevance of the topic, this paper aims at studying the unconformities two hip prostheses, titanium and other stainless steel front to standardizations. The implants studied were characterized by techniques: X-ray fluorescence, microanalysis Dispersion Energy X-ray diffraction, scanning electron microscopy and optical microscopy, and tests were carried out physic-mechanical traction and hardness. The unconformities present are analyzed and discussed.

Abstract: The paper presents the effect of laser shock processing on stainless steel 316L corrosion resistance. The samples were laser welded and mechanical treated using a Nd:YAG laser with a 1064 nm wavelength, and two different pulse density: 900 pulse/cm² and 1600 pulse/cm². After the laser shock processing, the samples were subjected to a seawater solution for corrosion testing. The curves obtained were statistically modeled using Stern-Geary equation. One may observe that the corrosion speed of the LSP samples treated with 900 pulse/cm² is eight times higher than the corrosion speed of the LSP samples treated with 1600 pulse/cm².