Possibility of Multi-material Laser Cladding Fabrication of Nickel Alloy and Stainless Steel

AbstractThere are some applications in the industry for multi-material components, including device engineering and multifunctional surface engineering, having to eliminate a brazing or welding technological step. This study investigates the laser cladding process parameters, related single track geometry and quality of multi-material samples. The optimal process parameters for steel were found of 0.21-0.26 J/mm2 and 0.25 10-2 g/mm under the scanning velocity of 1400-1700 mm/min and powder feeding of 4.2-4.5 g/min. The bimetal thin walls, cylinders and cubes were manufactured within the optimal conditions. The requirements of steel and nickel joining were explored. For the examination, the optical microscopy, SEM, EDX microelement analysis and hardness analysis were involved

Monitoring of Single-Track Degradation in the Process of Selective Laser Melting

Selective laser melting machines provide the optimal working parameters for manufacturing during the process. However, the laser interaction with metal powder is an unstable. The gasdynamic flows make powder particles move and escape from the melt pool. This phenomenon leads to an irregular distribution of the material volume being remelted. Since the energy is constant during the process, single-tracks with different geometry are appeared and their superposition forms the 3D-object. To detect the process abnormality of stable track formation there was developed a control system based on morphological analysis of thermal image obtained by IR-camera. The temperature field distribution along the image matrix’s row with the maximum temperature was used as influencing factor on stable track formation. Roughness was reduced from 39.9 to 6.6 µm by using control system with the same process parameters. The obtained results can be applied in industrial SLM machines with the integrated active control system.Mechanical Engineerin

Study of oxygen effect on the melting pool temperature during selective laser melting

The on-line optical diagnostics studies of selective laser melting are difficult to accomplish due to the need of closed chamber of inert gas protective atmosphere. In this term, this study was initiated to make evidence of oxygen influence on the signal from the melt pool. The results make clear the temperature growth with presence of oxygen and its effect on the metallurgical contact of the single-track to the substrate. It was shown that for both used materials, the oxidation leads to an overheating but the metallographic quality differs. The experiments highlighted that the optical diagnostic means such as IR thermography camera is suitable but not sufficient solution for process control and it needs adequate evaluation. Using the track width as an approximation of the melt pool width at melting point, it was possible with some assumptions to restore the true temperature of the studied zone

Study of 3D Laser Cladding for Ni85Al15 Superalloy

AbstractConditions of successful3D laser cladding for Ni based superalloy were studied. A high power Yb-YAG laser was used to create a molten pool on a stainless steel substrate into which Ni85Al15 powder stream was delivered to create 3D samples. The effect of different laser parameters on the structure and the intermetallic phase content of the manufactured samples were explored by optical metallography, microhardness, SEM, X-ray, and EDX analysis. The cladding of the Ni3A1 coating with small dilution into substrate can be obtained at the appropriate power density of about 2-8J/mm2 under the laser scan velocity of 100-200mm/min and the powder feed rate ∼ 3.8g/min

Study of layers’ structure defects of 3D objects obtained by selective laser melting

Current work was aimed to study of layers’ structure defects of 3D-objects obtained by selective laser melting with the modulated laser beam mode. Traditionally Gaussian laser beam mode uses for the processing in selective laser melting. On the developed experimental setup, the alternative laser beam modes as Flat-top and Inverse Gaussian were obtained. With the carried out experiments 3D-objects contained 10 layers were produced from CoCrMo powder with the diameter of granules less than 20 μm. The layers’ structure defects as penetration of the substrate material into the body of produced objects were studied by optical and scanning electronic microscopy