Process parameter optimization for Laser Metal Deposition using Hastelloy X blown powder

Hastelloy X (HX) is a nickel-base superalloy with strong resistance to oxidation and stress corrosion cracking combined with high temperature strength, these characteristics make it perfect for gas turbine engine components. The lack of machinability of this material makes laser metal deposition (LMD) suitable for the production and/or repair of components of HX, which uses a laser beam to melt the powder particles. Moreover, LMD has the features and versatility to implement this technology in the industry. The objective is to analyse a design of experiment covering a range of process parameters (laser power, scanning speed and powder feed rate) to find a suitable parameter set for using LMD with Hastelloy X powder. Properties of interest are build rate, microstructure, and minimum defects such as pores and cracks. Based on a design of experiments, 11 samples with 4 walls of different layers (15 layers, 5 layers, 3 layers and 1 layer) were printed. Then the samples were analysed using a light optical microscope and a hardness test along the build section. The results showed that each parameter has a different effect on the geometry accuracy. On the other hand, only scanning speed had a directly proportional effect on the microhardness. However, the powder feed affected the distance where the highest hardness point was found. Regarding the defects such as cracks and pores, any parameter had an important role, all the pores where evenly distributed on the laterals of the build. Moreover, cracks caused by lack of fusion where only found on one sample. Concerning the microstructure, all the samples presented the same evolution, the lower layers microstructure consists of fine columnar dendrites with an equiaxed morphology growing perpendicularly to the substrate in vertical direction, whereas the top layers consist of coarser columnar dendrites with bigger grain width. To sum up, with the analysis made in this study, it can be concluded that the parameter range used to print HX with LMD are suitable for the fabrication of engine complex part

Estudi i disseny d'un sistema de suport mecànic de bicicleta per tal d'estalviar l'espai a l'hora de guardar-la a casa

El propòsit d’aquest estudi pretén solucionar la problemàtica de l’espai que es malgasta mentre es guarda la bicicleta dins de casa. Es presentaran diverses alternatives de disseny del prototip, extretes d’un estudi de mercat i d’una enquesta. Finalment, s’explicarà la solució definitiva, es validarà empíricament i es presentaran els avantatges respecte els altres suports del mercat

Estudi i disseny d'un sistema de suport mecànic de bicicleta per tal d'estalviar l'espai a l'hora de guardar-la a casa

El propòsit d’aquest estudi pretén solucionar la problemàtica de l’espai que es malgasta mentre es guarda la bicicleta dins de casa. Es presentaran diverses alternatives de disseny del prototip, extretes d’un estudi de mercat i d’una enquesta. Finalment, s’explicarà la solució definitiva, es validarà empíricament i es presentaran els avantatges respecte els altres suports del mercat