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The problems of a material selection for making the boiler pipes in a responsible steam plant and the technology for their welding are considered in this paper. The boiler is screened, complex, radiating energetic plant, with the natural water circulation in the hanging steel structure. Based on the legal regulations, the mandatory periodic reparation of the most important components is performed. This is why the check of mechanical properties, for the used and new materials for eventual replacement and building-in was done, as well as the check of the prescribed reparation procedures. The components that were in exploitation were checked, since their properties change with time. Checking consisted of testing the tensile material properties at room and elevated temperatures, measurements of hardness and analysis of materials’ microstructures. Besides the experimental tests, the numerical modeling and analysis of the workload of the fluid transporting pipes was conducted. In that way it was established which material is optimal for manufacturing the boiler pipes. [ABSTRACT FROM AUTHOR]

This research work analyses the thermal, metallurgical and physical stages of AISI 304 Stainless Steel-Copper dissimilar couple during laser welding in keyhole mode numerically and then validated experimentally. 10.6 μ m wavelength CO2 laser welding machine is used for conducting this experimental analysis and the process is simulated by finite volume method. For making the dissimilar couple, a volumetric Gaussian heat source is applied symmetrically on the both metal domain and it is getting an asymmetric molten pool shape. It is observed that the computational model have good concurrence with the experimental results, after the calibration between simulation and experimental results for the same parameter set. [ABSTRACT FROM AUTHOR]