A metallurgical investigation on a failed superheater tube used in a thermal biomass power plant

This article described the investigation of the failed superheater tube made of SA210 Grade C used in a biomass power plant. Visual inspection, microstructural examination, chemical analysis and hardness measurement were employed to analyze the causes of the superheater tube failure. Results from the investigation showed that the major cause of this failure was mainly related to the long-term overheating, resulting in the occurrence of the excessive thermal oxidation and graphitization. The excessive thermal degradation accelerated the reduction of the wall tube and promoted the build-up of the stress acting on the tube. Graphitization degraded the microstructure of the tube, reducing the mechanical performance of the tube. The combined effects from the severe thermal oxidation and graphitization attributed to the premature failure of the tube. It is therefore advised to use the correct material, SA213 T22, in the failed section. Material specification examination for superheater regions prior to tube installations should be performed to avoid the use of the inappropriate material. The temperature monitoring and mapping in this section were also suggested.

Parametric and Metallurgical Investigation of Modified 3D AM 80 HD Steel for Wire and Arc Additive Manufacturing

Wire and arc additive manufacturing (WAAM) is an advanced 3D printing method for metallic materials on the foundation of traditional arc welding processes. WAAM is regarded as a proper way to manufacture large-dimensional metallic parts with the combination of high deposition rate and low cost. In this research, a specifically designed and manufactured low carbon high strength steel (Grade 3D AM 80 HD) wire, equivalent to a composition of AWS ER 110S-1 wire, was deposited using WAAM to print a muti-beads wall aiming to explore its feasibility for heavily loaded marine applications. A parametric investigation was proceeded to find the optimal deposition voltage and overlap ratio. A vertical position compensation method was adopted to optimize the step-up distance for welding torch between neighboring layers. Microstructure of the deposited component was characterized and also indicated by Thermal-Calc Software, followed by the measurement of hardness and prediction of tensile strength. Furthermore, a comparison of tensile strength of the WAAMed 3D AM 80 HD wall, 3D AM 80 HD wire, AWS ER 110S-1 wire, and a WAAMed wall produced by wire manufacturer (Voestalpine Böhler Welding Corporation) was conducted.

Mechanical And Metallurgical Investigation Of Tig Welded-Brazed Aluminum And Stainless Steel Disimilar Joint By Using Copper Filler Rod

Automobile bodies made by mix of steel and aluminum composites are getting famous in present days to decrease weight. Present work means to exhibit the strength of Aluminum and steel welded joint. Primary measures centered in this work are strength forecast, streamlining of welding measure boundaries and investigation of intermetallics. Base materials utilized are AA6061 aluminum alloys and SS304 hardened steel alloy. BCuP-4 copper filler bar is utilized for TIG welding/brazing of base metals. Taguchi L27 symmetrical exhibit with three elements is taken for plan of analyses. Analysis of Variance (ANOVA) a tool used to determine a remarkable effect of welding parameters and their performance significantly. In addition, experimental Tensile strength is compared to predicted values based on ANN. The results were found to be satisfactory. Formation Of IMCs were studied by doing SEM analysis.

Metallurgical Analysis as a Useful Method for Fire Investigation: the Case of Galvanized Steel Sheets

In this work, fire simulations were carried out on zinc-coated steel sheets usually employed for the structural parts of furniture, transformer rooms and aeration pipes. The thermal alteration induced by the fire was simulated by heating samples at 13 different temperatures (from 20° C to 1050° C) and for different exposure times (1 h and 6 h) in a laboratory furnace. The metallurgical investigation concerned the surface coloring by photographic analysis, the morphology and chemical composition of the surface oxides by SEM and EDS and the microstructure modifications as a function of the temperature by LOM. The influence of the different parameters was discussed by a statistical approach. The obtained results allowed to associate the temperature to one or more alteration of the steel microstructure and of the color, the morphology and the chemical composition of the surface oxides.

A Novel Approach of Friction Stir Cladding of Aluminum on Carbon Steel Plate; Experimental Investigation and Material Characterization

Cladding is usually used to improve the material functionality (i.e. corrosion, wear, and oxidation) and to improve the mechanical and thermal properties of the components in different industries. In this study, a new cladding approach based on the friction stir processing was successfully employed on carbon steel plate with 6061-T6 Aluminum alloy. The mechanical and metallurgical properties of the cladding layer were examined at different process parameters. Metallurgical investigation of ST/Al interface was also evaluated using the Scanning electron microscope (SEM) and Optical microscope (OM). Two alloys were mixed uniformly together in the proper process conditions. Based on the results, the decrease of rotational speed from 1200 rpm to 800 rpm at a constant traverse speed of 15 mm/min, the cladding strength increased from 3.7 KN to 4.8 KN. At constant rotational speed of 800 rpm, with an increase in traverse speed from 15 mm/min to 35 mm/min, the cladding strength increased from 4.8 KN to 6.6 KN.