Papers by Keyword: Carbon Steel

Abstract: This paper presents a case study of an in-service failure occurred in a pressurized gas supply pipeline, which has been recurring in recent years, particularly during the winter season. The investigation focused on two pipe coupons extracted from a DN 300 pipeline, which had sustained damage while in operation as part of a natural gas pipeline. Through the implementation of mechanical and non-destructive testing methods on the pipe couplings and their welds, multiple non-conformities were identified. These non-conformities were found to be the root causes of failures that occurred after welding and during operation. The findings of this investigation have led to several valuable comments and recommendations, which are beneficial for manufacturing companies and clients alike. Implementing these suggestions can contribute to enhanced safety and operational efficiency in gas pipeline systems.

Abstract: This study provides a comprehensive investigation into the microstructure, hardness, tensile strength, and bending fatigue behavior of a Wire Arc Additively Manufactured (WAAM) component composed of dissimilar materials—Carbon Steel (CS) and 316L stainless steel. Microscopic analysis reveals distinct microstructural characteristics, such as equiaxed ferrite grains in WAAM CS and a coarse columnar structure with delta-ferrite phases in WAAM 316L. A macroscopic phase map indicates a predominantly Body-Centered Cubic (BCC) structure near the interphase, suggesting element migration between CS and 316L due to high heat input. Higher magnification scans highlight martensitic structures on both sides of the interphase, with the CS side exhibiting larger grain sizes. Hardness assessment along the built direction shows a peak hardness of 407 HV near the interphase on the 316L side, contrasting with the CS side's average interphase hardness of 316 HV due to larger grain sizes. The yield strength of both WAAM CS and WAAM dissimilar material was consistently measured at 392 MPa. In comparison, WAAM 316L exhibited a slightly lower yield strength of 359 MPa. Notably, WAAM 316L demonstrated the highest tensile strength among the materials, reaching 656 MPa. Meanwhile, WAAM CS displayed a robust tensile strength of 503 MPa, and the WAAM dissimilar material exhibited a yield strength of 520 MPa. In terms of elongation, WAAM CS and WAAM 316L showcased values of 44.9% and 49.6%, respectively. On the other hand, WAAM dissimilar material exhibited a somewhat lower elongation of 20.4%, suggesting a different mechanical behavior in terms of ductility. Bending fatigue tests on WAAM 316L, WAAM CS, and the dissimilar material reveal a fatigue limit of approximately 225 MPa for WAAM 316L, 210 MPa for WAAM CS, and approximately 210 MPa for the dissimilar material. In the low-cycle and medium-cycle regimes, the dissimilar material exhibits slightly superior fatigue strength, potentially due to its marginally higher static strength. Notably, consistent fractures on the CS side during fatigue tests underscore a recurring behavior in the dissimilar material.

Abstract: The study investigates the impact of severe shot peening on the fatigue strength of wire arc additively manufactured carbon steel. Initial characterization revealed a material with prominent equiaxed grains and large grain sizes. However, the application of SSP induced a considerable reduction in grain size, particularly on the surface, consequently enhancing the surface's strength and hardness, yet leading to an inhomogeneous structure within the WAAM CS SSP part. Hardness measurements demonstrated a substantial impact on surface hardness, reaching a depth of approximately 0.4 mm, with a 64% increase observed due to SSP, elevating it from an average of 165 HV to a maximum of 270 HV near the surface. Tensile tests on WAAM CS and WAAM CS SSP displayed notable improvements in mechanical properties following SSP treatment. Yield strength increased by approximately 5%, and ultimate tensile strength rose by 2.5%, resulting in a peak tensile strength of 513 MPa. However, this enhancement was accompanied by reduced ductility, evidenced by decreased elongation from 44% in WAAM CS to 35% in WAAM CS SSP. Bending fatigue tests highlighted a significant enhancement in fatigue resistance due to SSP treatment. The fatigue limit increased by 21% from 190 MPa for WAAM CS to 230 MPa for WAAM CS SSP, indicating improved resistance in both low-cycle and high-cycle fatigue regimes. This enhancement in fatigue resistance is attributed to the heightened mechanical strength post-SSP treatment, suggesting a trade-off between increased strength and reduced ductility. The results demonstrate that SSP significantly enhances surface attributes, strength, and fatigue resistance of WAAM CS. This advancement bears implications for engineering applications where enhanced mechanical properties and fatigue resistance are vital, despite the induced trade-offs in material characteristics.

Abstract: This study presents a comprehensive exploration of the fatigue resistance of wire arc additive manufacturing (WAAM) carbon steel for lattice structures. Microstructural analysis unveils substantial grain dimensions characterized by a distinctive crystallographic configuration. These grains exhibit equiaxed characteristics, demonstrating uniform dimensions in all directions. The prevailing microstructure is dominated by ferrite grains. In tandem with the microstructural insights, hardness evaluations were conducted in correspondence with the part's deposition direction. The analysis of these measurements unveiled a consistent base material hardness of approximately 159 HV. The uniform distribution of hardness profiles supports the deduction that WAAM carbon steel uniformly embodies strength attributes. This congruence aligns harmoniously with the uniform microstructure evident in microscopic analyses. The yield strength of the WAAM carbon steel exhibits higher values in the build direction, peaking at 392 MPa. The bending fatigue tests revealed a fatigue limit approximating 180 MPa for WAAM carbon steel, evident in both the build and deposition directions. Fatigue strength of WAAM carbon steel mirrors that observed for reference material S355MC steel sheet.

Abstract: Various industrial parts and equipment made of steel need to withstand demanding conditions. In order to increase performance and lifetime, surface processing and functional coatings can be applied. In this study we report on the evaluation of coated carbon steel with commercial corrosion-resistant powders Diamalloy 4276 and Woka 7502 by Oerlikon Metco, using thermal spraying. Further functionalization is performed by rendering thermal sprayed surfaces syperhydrophobic via gas phase deposition of trichloro-1H,1H,2H,2H-perfluorooctyl silane, (PFOTS). Electrochemical impedance spectroscopy, contact angle and water condensation studies reveal the protective properties of coatings prepared by both materials as well as the superiority of Diamalloy 4276 based coatings. Corrosion was evaluated under a harsh 20% w/w H₂SO₄ environment. Rendering the coating superhydrophobic improves water condensation under the tested conditions of high (80%) relative humidity.

Abstract: This paper presents the results of factorial experiment applied to optimize Matrix‑Assisted Pulsed Laser Evaporation (MAPLE) and Pulsed Laser Deposition (PLD) coating technologies used to improve the corrosion resistance of steels. MnTa₂O₆ pseudo-binary oxides and 5,10-(4-carboxy-phenyl)-15,20-(4-phenoxy-phenyl)-porphyrin was used for these experiments to obtained thin film coating system of hybrid nanostructures. Based on factorial experiments, correlations between the main technological parameters of the coating process (MAPLE laser energy E_MAPLE [mJ], PLD laser energy E_PLD [mJ]) and porphyrin concentration and the main related property of the coating system (corrosion protection factor) were determined. The base material used as substrate in the experiments was S235JR+C. Electrochemical measurements showed that by applying the appropriate parameters of the coating technologies, homogeneous layered sandwich thin films were obtained and corrosion rate was reduced by more than 7 times.

Abstract: In the process of oil and gas extraction, N80 steel is used as a common tubing material. CO₂ corrosion has become one of the most dangerous problems in its entire life cycle. In this paper, the conditions of different temperatures (90-220 °C) and CO₂ partial pressure (0.2-3 MPa) were selected, and the dynamic rotating high-temperature autoclave was used to simulate N80 steel corrosion in formation water environments. The results showed that the corrosion rate of N80 steel gradually decreased with the increase of temperature, and the corrosion rate was the lowest at 150 °C. In addition to this, with the increase of CO₂ partial pressure, the corrosion rate first increased and then decreased. The corrosion rate was the highest when the CO₂ partial pressure was 0.8 MPa. Through surface analysis techniques (SEM and XRD) and electrochemical tests, it was found that the corrosion resistance of N80 under high temperature and high pressure is closely related to the corrosion product film (FeCO₃). The compactness of FeCO₃ product film determines the corrosion characteristics of the matrix.

Abstract: The worldwide need for lightweight, high-quality, high-performance, and low-cost materials is prompting a change in emphasis from unreinforced materials to reinforced/composite materials. The mechanical properties of the MHP reinforced aluminum composite are compared to those of the unreinforced metal using the data on the corrosion performance of maize husk particulate reinforcement on high 1170 Aluminium alloy in 0.00625 M H2SO4, 3.5 wt.% NaCl and a mixture of both solutions was studied using weight loss technique to determine the corrosion rates of the specimens. Optical microscopic analysis was also carried out on the specimens to determine the effect of the reinforcement on the microstructural properties of the material before and after corrosion. The corrosion rates calculated from the weight loss study revealed differences in the corrosion characteristics of the specimens in the various solutions when compared to the control specimen. The presence of reinforcement in the matrix was discovered to positively impact the corrosion behavior of composite materials via the production of corrosion resistant oxides. The electrochemical properties of maize husk enhances the corrosion resistance of the composite due to its ability to form a protective oxide film and chemically resistant inclusions on the surface of the material.

Abstract: Analysis and description of inhibition efficiency results for tea tree and grapefruit essential oil extracts (TTGP) on mild steel (MS) and alloy steel 3310 (AS3310) in 0.5 M H2SO4 solution was done. The results show TTGP performed effectively on MS at 2% to 3.5% TTGP concentration with final inhibition values of 71.70%, 79.25%, 83.58% and 92.45% at 240 h of exposure. Inhibition efficiency generally increased with TTGP concentration and exposure time, although inhibition efficiency at 2.5% 3% TTGP concentration decreased with exposure time. Effective TTGP inhibition performance on AS3310 occurred at 3% and 3.5% TTGP concentration only with final values of 72.50% and 73.25%. Inhibition efficiency of TTGP on AS3310 varied non-proportionately with its concentration. With respect to exposure time, inhibition efficiency of TTGP on AS3310 at all concentrations decreased. Results from ANOVA analysis shows TTGP concentration significantly influenced the performance output of TTGP extract with statistically significant factor of 85.73% and 84.78% (MS and AS3310). The corresponding values for exposure time, though determined to be statistically relevant is overwhelmingly far below the influence of exposure time at values of 4.63 and 14.27. Standard deviation data shows inhibition efficiency of TTGP on MS varied minimally from mean values at all concentrations (excluding 1.5% and 2% TTGP concentration). The corresponding values for TTGP on AS3310 were also generally low at all concentrations signifying stable inhibition performance. Data showed 48% and 18% of MS and AS3310 inhibition efficiency results are greater than 80% effective inhibition performance threshold at margins of error of 12.64% and 10%

Abstract: Carbon steel was coated with Cr-multi-walled carbon nanotube (MWCNTs) coatings via electrodeposition. In this article, the impact of a combination of MWCNTs into the chromium coating on the morphology of the coating surface and corrosion characteristics was inspected. The MWCNTs seem to be evenly distributed across the chromium layer, according to scanning electron microscopy (SEM). Electrochemical measurements were used to conduct corrosion tests on samples of MWCNTs– chromium composite coated and pure chromium coated samples in aqueous NaCl (3.5 wt.%). The outcomes demonstrated a considerable increase in the resistance of corrosion due to the inclusion of MWCNTs during the chromium deposition procedure. In addition, the mechanism of anti-corrosion of the composite coating is also presented. Using an electrolyte bath containing various concentrations of dispersed MWCNTs (0.5, 1, and 1.5 g/L), crack-free and compact coating of Cr-MWCNT composite were electrodeposited on the substrates of the mild steel. The potentiodynamic polarization technique was used to examine the coatings corrosion performance subjected to a 3.5 weight percent of NaCl medium. When compared to chromium coating, the Cr-MWCNT composite coating showed the lowest corrosion rate (1.045x10⁸ mpy) compared to chromium coating (4.891x10⁸ mpy).