Durability study of the aisi 1024hr and aisi 304hr alloys applied in the organic waste industry (original) (raw)
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Applied Sciences
AISI 347 austenitic steel is, as an example, used in nuclear energy piping systems. Piping filled with superheated steam or cooled water is particularly exposed to high stresses, whereupon local material properties in the pipes can change significantly, especially in the case of additional corrosive influences, leading to aging of the material. In the absence of appropriate information, such local material property variations are currently covered rather blanketly by safety factors set during the design of those components. An increase in qualified information could improve the assessment of the condition of such aged components. As part of the collaborative project “Microstructure-based assessment of the maximum service life of core materials and components subjected to corrosion and fatigue (MiBaLeB)”, the short-time procedure, StrainLife, was developed and validated by several fatigue tests. With this procedure, a complete S–N curve of a material can be determined on the basis of...
Applied Sciences
The assessment of metallic materials used in power plants’ piping represents a big challenge due to the thermal transients and the environmental conditions to which they are exposed. At present, a lack of information related to degradation mechanisms in structures and materials is covered by safety factors in its design, and in some cases, the replacement of components is prescribed after a determined period of time without knowledge of the true degree of degradation. In the collaborative project “Microstructure-based assessment of maximum service life of nuclear materials and components exposed to corrosion and fatigue (MibaLeb)”, a methodology for the assessment of materials’ degradation is being developed, which combines the use of NDT techniques for materials characterization, an optimized fatigue lifetime analysis using short time evaluation procedures (STEPs) and numerical simulations. In this investigation, the AISI 347 (X6CrNiNb18-10) is being analyzed at different condition...
Comparative and assessment study of torsional fatigue life for different types of steel
SN Applied Sciences
Different types of steel specimens were tested using low cycle torsional fatigue tests to evaluate the torsional behavior. During previous years many authors have developed empirical relationships related to stress amplitude with the life of failure in many types of steel materials. Studies continue to find the best experimental relationships for different subjects. In this study two main problems were considered: torsional fatigue study and comparing the behavior of different steel materials under the influence of torsional fatigue. The effect of temperature on the properties of these substances was also studied. A comparison and evaluation of torsional fatigue for different types of steel were found in this study. Three groups of steel specimen were selected for the present investigation, these included low carbon steel AISI 1020, stainless steel AISI 316L, and cold worked stainless steel AISI 304H. The tests were carried out for each group of the steel specimen using a fatigue machine under fully reversed low cycle at ambient temperature and 100 °C. The temperature range was chosen from room temperature to 100° C because the low carbon steel AISI 1020 material showed high ductility above 100 °C. The shear strain amplitude applied was selected between the max. and min. values of 0.18 and 0.02 respectively. A comparison was carried out between the three steel groups at ambient temperature, it was noticed that the ratio of life to failure for both AISI steels 316L and AISI 304H with respect to AISI 1020 showed an increase of 4 and 2.3 times respectively. Also, the ratio of life to failure showed an increase of 4 and 3.5 times respectively at 100 °C. That is mean the ratio of life to failure for AISI steel 316L with respect to AISI 1020 has no effect with the temperature change because their cycles of life have been affected in the same manner. AISI 304H showed a good withstand to the temperature change because the ratio of life to failure with respect to AISI 1020 has been increased.
To exploit the whole potential of Additive Manufacturing, it is essential to investigate the complex relationships between Additive Manufacturing processes, the resulting microstructure, and mechanical properties of the materials and components. In the present work, Selective Laser Melted (SLM) (process category: powder bed fusion), Laser Deposition Welded (LDW) (process category: direct energy deposition) and, for comparison, Continuous Casted and then hot and cold drawn (CC) austenitic stainless steel AISI 316L blanks were investigated with regard to their microstructure and mechanical properties. To exclude the influence of surface topography and focus the investigation on the volume microstructure, the blanks were turned into final geometry of specimens. The additively manufactured (AM-) blanks were manufactured in both the horizontal and vertical building directions. In the horizontally built specimens, the layer planes are perpendicular and in vertical building direction, they are parallel to the load axis of the specimens. The materials from different manufacturing processes exhibit different chemical composition and hence, austenite stability. Additionally, all types of blanks were heat treated (2 h, 1070 • C, H 2 O) and the influence of the heat treatment on the properties of differently manufactured materials were investigated. From the cyclic deformation curves obtained in the load increase tests, the anisotropic fatigue behavior of the AM-specimens could be detected with only one specimen in each building direction for the different Additive Manufacturing processes, which could be confirmed by constant amplitude tests. The results showed higher fatigue strength for horizontally built specimens compared to the vertical building direction. Furthermore, the constant amplitude tests show that the austenite stability influences the fatigue behavior of differently manufactured 316L. Using load increase tests as an efficient rating method of the anisotropic fatigue behavior, the influence of the heat treatment on anisotropy could be determined with a small number of specimens. These investigations showed no significant influence of the heat treatment on the anisotropic behavior of the AM-specimens.
Comparison of Fatigue Characteristic for AISI 1039 Steel with Surface Treatment
Wear and fatigue resistance in steel components used in various industries can be improved by surface treatments. Coatings systems which are used for improving the mechanical properties, generally, decreased the components fatigue life due to micro cracks, that propagate through the substrate , it is possible to improve the fatigue resistance of a component by the application of shot peening treatment, whose compressive residual stresses delay or eliminate the initiation and propagation of fatigue cracks. The aim of this study is to obtain the fatigue limit of untreated, shot peened, and hard chromium coating of medium carbon steel AISI 1039 and comparison between them. Fatigue tests were carried out using small samples with 4 mm diameter, with hard chromium layer of (47.1) µm thick. Rotating-bending fatigue test was carried out on samples after shot peening with steel balls of about 20 minutes peening time. Experimental results showed that hard chromium electroplating decreased the fatigue life and fatigue limit in comparison with the uncoated steel. As the highest thickness for coating was 23µm. On the other hand, Shot peening Results indicated that the fatigue strengths of samples are increased and the highest fatigue limit was (298.566Mpa) after treated the samples by shot peening for 20 minutes.
Austenitic stainless steels are widely used in the chemical, petrochemical and foodprocessing industries due to their excellent corrosion resistance and good mechanical properties. However, due to their inherent austenitic structure, they have relatively low hardness, as well as poor wear resistance and short fatigue life. Thermochemical surface treatments are used to improve the wear resistance, hardness and fatigue life. Austenitic stainless steels are difficult to carburise due to the tenacious Cr 2 O 3 layer on the surface, although plasma and gas carburising have proven to be very effective. However, this investigation sought to understand the effect of high carburising temperature on the mechanical properties of AISI 316L steel, without the removal of the tenacious Cr 2 O 3 surface layer.
Nonlinear engineering, 2024
Improving corrosion resistance in alloys made of stainless steel is an important innovation on the petroleum trade. The effect of heat treatments (HT) and cold working on the corrosion behaviour, surface hardness, and microstructure of 316 stainless steel was investigated experimentally. The corrosion environment is seawater and crude oil. The corrosion rates (CRs) were obtained using the mean loss of weight approach, which was then optimised using the Taguchi method. The specimens used in this study are made of 316 stainless steel rod, which is first annealed to obtain the qualities of the raw material before being put through a tensile test to assess the mechanical characteristics of the metal. After cold working, the hardness test, the corrosion test utilising the lost weight method, and the microstructure test are all carried out. By performing these tests, the metal show excellent mechanical properties such as yield stress, tensile stress, and hardness; in the corrosion test, the raw metal show higher resistance in both seawater and crude oil, while in cold working and HT with cold working, samples show higher corrosion The HT samples had the lowest corrosion resistance as the cold working percentage increased. In this work, the input parameters such as ultimate corrosion media, HT and cold work (CW) are optimised utilising a multiple objective optimisation approach that uses weighted grey relational analysis. Two objectives, that are CR and Hardness (H), are simultaneously optimised. We suggested a quantitative approach to establish the weight factors of various responses for grey relational analysis called weighted grey relational analysis. The optimum input parameters were determined using weighted grey relational analysis, and the outcomes showed that HT is the most relevant parameter. Cold working has been observed in association with stress-related twinning and austenite phase deformation, resulting in fast grain splitting and the production of a microstructure that resembles a ribbon composed of austenite and ferrite.
Materials Research, 2017
Austenitic stainless steels are high corrosion resistant alloys widely used in many industrial fields. Among this family of steels, AISI 317L stands out due to its higher localized corrosion resistance when compared to the traditional grades AISI 304L and AISI 316L. In some applications in oil refineries, the AISI 317L is being specified for services at moderately high temperatures. At the same time as it is sought to use new stainless steels, is also desirable to apply and develop emerging welding processes, replacing conventional ones, in order to achieve better behavior in service. In this respect, this work studied the effects of thermal aging on the toughness and resistance to pitting corrosion of AISI 317L steel weld metals produced by the Gas Tungsten Arc Welding (GTAW) and Friction Stir Welding (FSW) joining processes. After prolonged exposures at 450°C, for 200h, 300h and 400h, the microstructural characterization by scanning electron microscopy (SEM), toughness evaluation and anodic polarization tests in 3.5% NaCl solution were performed. The results showed that the increase of the exposure time in both weld metals caused a toughness decrease. The pitting potentials measured in the polarization tests also decreased with the aging at 450ºC.
Effect of Thermal Cycles on the Fatigue Life of Aisi 321 Stainless Steel
2007
An experimental-numerical study was focused on the effect of the temperature difference of cycling on the life of austenitic stainless steel under high-temperature thermal fatigue conditions. AISI 321 steel was chosen as an experimental material. Particularly initiation stage of thermal fatigue cracks in AISI 321 steel subjected to repeated thermal shocks was investigated. Non-standard experimental set-up was developed in order to rapid crack initiation of tested specimen. The effect of the temperature difference of cycling was studied by varying ∆T from 150°C to 340°C while holding the lower temperature constant at 100°C. The initiation stage is interpreted as specifying the number of cycles required for the formation of an engineering crack 0.5 mm long. The most of standard lifetime curves for fatigue crack initiation, which are measured on strain-controlled mechanical tests of round polished bars with various diameters in isothermal conditions, are based on the phenomenological M...
Structural integrity, 2019
For the comprehensive understanding of the fatigue mechanisms of mechanical and thermally aged materials in power plant reactors, an innovative, resource-and time-optimized approach based on non-destructive testing methods is used. Beside investigations on AISI 347 austenitic stainless steel under cyclic loading, magnetic, resistometric and electrochemical measurement techniques were applied to monitor the proceeding fatigue behavior. Qualitative values indicate surface passivation effects and microstructural changes, which are directly related to fatigue states. In total strain-controlled increase tests, cyclic investigations for the initial and a mechanically and thermal aged condition were carried out under distilled water environment at ambient temperature. In comparison to the initial state, the aging process shows a significant influence on the fatigue behavior with a reduction of the stress amplitude at failure down to 75%.