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Search Results: 1 - 10 of 4549 matches for " stainless steel "
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Corrosion Study of AISI 304, AISI 321 and AISI 430 Stainless Steels in a Tar Sand Digester  [PDF]
L.E. Umoru, A.A. Afonja, B. Ademodi
Journal of Minerals and Materials Characterization and Engineering (JMMCE) , 2008, DOI: 10.4236/jmmce.2008.74022
Abstract: This work has investigated the corrosion properties of three types of stainless steels in a tar sand digester environment with the aim of establishing their relative resistances in the environment. The corrosion experiments for the stainless steels were conducted by the non-electrochemical immersion technique with corrosion rates expressed in mils per year (mpy). The spectroscopy analysis of the Nigerian tar sand was done by the energy dispersive x-ray analysis. The surface study of the corroded stainless steels was accomplished via a scanning electron microscopy (SEM) to reveal the form of corrosion. The results of the corrosion experiments show that all the stainless steels have a relatively low corrosion rates (<5mpy). The SEM analyses of their corroded surfaces however revealed great tendency in them to exhibit crevice and pitting corrosions. On the basis of resistance to the two forms of corrosion the AISI 321 stainless steel exhibited the best resistance in the environment.
Duplex Stainless Steel Welds and their Susceptibility to Intergranular Corrosion  [PDF]
B. Gideon, L. Ward, G. Biddle
Journal of Minerals and Materials Characterization and Engineering (JMMCE) , 2008, DOI: 10.4236/jmmce.2008.73019
Abstract: Duplex stainless steels (DSS) as alternatives to conventional austenitic stainless steels for the construction of pipelines is becoming more wide-spread, particularly for sour service applications where corrosion resistance / stress corrosion cracking resistance is required in aggressive chloride /sulphide environments. While these steels show many superior characteristics, limitations are associated with the welding of these steels, particularly controlling the weld structure and properties and understanding how the weld metallurgy may influence the susceptibility to intergranular corrosion (IGC). The focus of this paper is to report on the findings from a detailed study of the various weld sections within a DSS pipeline, as a function of heat input and type of weld, in terms of the metallurgical structure, composition and mechanical properties and to assess the susceptibility to IGC. Welding was performed using the manual Gas Tungsten Arc Welding (GTAW) technique at both high and low heat input conditions. Two different join configurations (double bevel single V bevel and double bevel single U joint configuration) were adopted. Structural analysis consisted of (i) optical microscopy of welded specimens; (ii) ferrite content determination; (iii) Vickers hardness measurements; (iv) Charpy impact studies and (v) transverse tensile testing. Two test methods namely a modified ASTM A262 and a modified Double Loop Electrochemical Potentiokinetic Reactivation (DL-ERP) test was used to determine susceptibility to IGC. The electrolyte solution used was 0.5M H2SO4 + 0.001 M TA (thioacetamide). The test was conducted at 60 °C. The potential was scanned from -500 mV (SCE) to +200 mV (SCE) and back to 500 mV (SCE) at a rate of 1.67 mV/s. The ratio of the reactivation charge to the passivation charge was calculated. From the results obtained it can be shown that the fill region was most susceptible to IGC for all weld conditions.
Electrochemical Investigation of Corrosion on AISI 316 Stainless Steel and AISI 1010 Carbon Steel: Study of the Behaviour of Imidazole and Benzimidazole as Corrosion Inhibitors  [PDF]
Roberta R. Moreira, Thiago F. Soares, Josimar Ribeiro
Advances in Chemical Engineering and Science (ACES) , 2014, DOI: 10.4236/aces.2014.44052
Abstract: An electrochemical investigation of the corrosion on AISI 316 austenitic stainless steel and AISI 1010 carbon steel in sodium chloride solution (3.0 wt.%) was performed in the absence and presence of imidazole and benzimidazole corrosion inhibitors. The results showed that at any inhibitor concentration (25 ppm to 1000 ppm), there was an increase in the polarisation resistance of both steels. The highest efficiency of corrosion inhibition was obtained using imidazole at a concentration of 50 ppm for both steels, with values of 96% for the AISI 316 stainless steel and 73% for the AISI 1010 carbon steel.
Effect of temperature on the level of corrosion caused by heavy petroleum on AISI 304 and AISI 444 stainless steel
Machado, Jo?o Paulo Sampaio Eufrásio;Silva, Cleiton Carvalho;Sobral-Santiago, Ana Vládia Cabral;Sant'Ana, Hosiberto Batista de;Farias, Jesualdo Pereira;
Materials Research , 2006, DOI: 10.1590/S1516-14392006000200005
Abstract: this work presents a study on the influence of national heavy petroleum in the corrosion of the aisi 444 and aisi 304 stainless steels in simulated refining operation conditions. the petroleum was first characterized through physicochemical analysis (density, fluidity point, viscosity, sulfur concentration). in an attempt to understand the corrosion effect of temperature and of the type of heating the referred types of steel thermal treatments were carried out at three levels of temperature (200, 300 and 400 °c). the procedure was done in conditions close to those in the distillation column. heat was gradually increased from room temperature, and directly heated to working temperature. each treatment took 4 hours to be completed. scanning electronic microscopy (sem) and the analysis of x rays dispersive energy (edx) were used after the trials to characterize the samples. the results show that treatment temperature, as well as the type of heating, has distinct influences on each type of steel.
Processing of a duplex stainless steel by equal channel angular extrusion
Farias, F.A.;Pontes, M.J.H.;Cintho, O.M.;
Matéria (Rio de Janeiro) , 2010, DOI: 10.1590/S1517-70762010000200036
Abstract: a uns s32205 duplex stainless steel was processed by ecae in three different velocities, at room temperature, and heat treated in different temperatures and times to evaluate recrystallization. attrition forces promoted great deformation heterogeneity in the samples sections, with hardness increase, and morphology changes in the grains and changing orientation through the processed samples. in treated samples surface, two types of distinct structures was formed, with surfaces positioned in 90o and 120o angles, probably because the annihilation of pilled dislocations in ferrite based centered cubic structure and austenite face centered cubic structure, respectively. the induced martensite by cold deformation was also observed. some samples demonstrate located points of recrystallization in grain boundaries for some treatment conditions, the number of recrystallization nuclei increased with the increase of treatment time.
A corros?o do a?o inoxidável austenítico 304 em biodiesel
Gallina, André Lazarin;Stroparo, Erivelton César;Cunha, Maico Taras da;Rodrigues, Paulo Rogério Pinto;
Rem: Revista Escola de Minas , 2010, DOI: 10.1590/S0370-44672010000100012
Abstract: fuel distribution uses 304 stainless steel containers for the storage of biofuels, however, there are few reports in the literature about the corrosive aspects this steel in biodiesel. the objective of this research is to study the corrosive behavior of 304 austenitic stainless steel in the presence of biodiesel, unwashed and washed, with aqueous solutions of citric, oxalic, acetic and ascorbic acids 0,01 mol l-1, and compare with results obtained for the copper (astm d130). the employedtechniques were: atomic absorption spectrometry (aas) and optical microscopy (om). the results of eaa showed a low rate of corrosion for the stainless steel, the alloys elements studied were cr, ni and fe, the highest rate was observed for the chrome, 1.78 ppm / day in biodiesel with or without washing. the om of the 304 steel, when compared with that of copper, has a low corrosion rate in the 304 steel/biodiesel system. not with standing, this demonstrates that not only the 304 steel, but also the copper, corrodes in biodiesel.
Estudo do comportamento eletroquímico de azóis para o a?o inoxidável AISI 430 em H2SO4 1 mol L-1
Tussolini, Martha;Spagnol, Cristiane;Alves, Guilherme José Turcatel;Cunha, Maico Taras da;Rodrigues, Paulo Rogério Pinto;
Rem: Revista Escola de Minas , 2010, DOI: 10.1590/S0370-44672010000100018
Abstract: corrosion is an undesirable process that occurs in metallic materials. studied was the effect of inhibiting benzotriazole (btah), benzimidazole (bzm) and indole in different concentrations for the stainless steel (ss) aisi 430 in h2so4 1 mol l-1. the techniques employed this research were: anodic potenciostatic polarisation, electrochemical impedance spectroscopy, optical microscopy and scanning electron microscopy. the curves of anodic polarisation showed that btah, bzm and indol act as corrosion inhibitors for 430 ss, at concentrations of 1x10-3 and 5x10-4 mol l-1, but do not inhibit corrosion for concentrations equal to or less than 1x10-4 mol l-1. the in-crease of the efficiency in relation to the inhibitory substances studied followed this order: indol
Development and Evaluation of a Prototype Refrigerated Cooling Table for Conference Services
Abubakar Mohammed,Andrew E. Elaigu,Akinola A. Adeniyi,Abdulkadir B. Hassan
International Journal of Engineering and Technology , 2012,
Abstract: This paper presents the development and evaluation of a prototype refrigerated cooling table for conference services. The major components of the table are compressor, condenser, evaporator, capilary tube, thermostat and table metal wooden frame. The table uses vapour compression cycle based on the Evans-Perkins (reverseRankine) cycle as its principle of operation. The evaporator has three cabinet ports. Plywood and square mild steel pipes are used for the construction of the table frame. The refrigerated cooling table successfully reduces temperature of beverages from 35°C to 15.5°C, 13°C and 11°C, when placed in a plastic, glass and stainlesssteel containers respectively. The refrigerated cooling table performs better when compared with a standard domestic refrigerator. The coefficient of performance using experimental values is 5.14 with a compressor power of 69.3W for three participants.
Corrosion of an austenite and ferrite stainless steel weld
VLADANA N. RAJAKOVI?-OGNJANOVI?,BRANIMIR N. GRGUR
Journal of the Serbian Chemical Society , 2011,
Abstract: Dissimilar metal connections are prone to frequent failures. These failures are attributed to the difference in the mechanical properties across the weld, the coefficients of thermal expansion of the two types of steels and the resulting creep at the interface. For the weld analyzed in this research, it was shown that corrosion measurements can be used for a proper evaluation of the quality of weld material and for the prediction of whether or not the material, after the applied welding process, can be in service without failures. It was found that the corrosion of the weld analyzed in this research resulted from the simultaneous activity of different types of corrosion. In this study, electrochemical techniques including polarization and metallographic analysis were used to analyze the corrosion of a weld material of ferrite and austenitic stainless steels. Based on surface, chemical and electrochemical analyses, it was concluded that corrosion occurrence was the result of the simultaneous activity of contact corrosion (ferrite and austenitic material conjuction), stress corrosion (originating from deformed ferrite structure) and inter-granular corrosion (due to chromium carbide precipitation). The value of corrosion potential of –0.53 V shows that this weld, after the thermal treatment, is not able to repassivate a protective oxide film.
Mechanical Characteristics of Superaustenitic Stainless Steel Type 30Cr25Ni32Mo3 at Elevated Temperatures  [PDF]
Gholam Reza Ebrahimi, Hamid Keshmiri, Hadi Arabshahi
Materials Sciences and Applications (MSA) , 2010, DOI: 10.4236/msa.2010.16047
Abstract: In making tubes of corrosion resistant and hardly deformed steels and alloys, the pilger rolling method is used for hot rolling of final thick-walled tubes or mother tubes of large diameters (above 300 mm) and small quantities of other size tubes when no other, more efficient tube rolling or extrusion equipment is available. To clarify individual parameters of the production process and make choice of the deformation-and-temperature parameters, mechanical properties of the alloy type 30Cr25Ni32Mo3 Superaustenitic Stainless Steel at various temperatures were studied. The tests have been performed using samples taken from the forged 400 mm diameter billet to determine strength and plastic properties of the billet metal at various temperatures and its macro- and microstructure. The test results will be used in the choice of optimum conditions of preheating of the billets and hot rolling of tubes. On the whole, it should be stated that as-forged alloy 30Cr25Ni32Mo3 features a favorable combination of strength and plastic properties in the hot-working temperature range of 1075-1200?C.
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