The Microstructrue And Mechanical Characters Of Rene95 Laser Solid Forming

Laser Solid Forming (LSF) was an advanced fabrication technology that developed from Rapid Prototyping technique in 1990's and progressed very fast in the recent years. It has a promising future since a density metal component can be rapidly deposited by laser cladding metal materials additively. Compared with the traditional manufacturing technology the components fabricated by LSF have better mechanical properties.This paper has made a systematically research on the LSF's processing characteristic. The results showed that the processing parameters (such as laser power, the diameter of laser, scanning speed of laser beam, ratio of overlapping) are important to acquire a perfect component. Furthermore, in order to assure geometric properties (accuracy, surface finish), the structure of the off-axial powder nozzle was improved to avoid the oxidation of the molten pool.The density metal test sample of Rene95 high-temperature alloy was made by LSF through optimizing the processing parameters. The microstructure of LSF components was made up of fine columnar dendrites, which grow epitaxially from the substrate, and the mean primary dendrite spacing was 26.58 m. The mechanical property of the test sample was improved through heat treatment further. After heat treatment process, the primary strengthening phase Y ' increased both in the quantity and size. The quantity of phase Y ' increased to 45% and the size of them became more uniform (about 100nm) as the test sample experienced heat treatment. These change of the strengthening phase in the quantity and size play a remarkable role in improving mechanical property of the test sample.The test result of the Rene95 sample showed that the maximum ultimate tensile strength can be as high as 1400MPa and has reached 97.9% of that of the sample fabricated by powder metallurgy (PM). The plastic elongation of the test sample can even exceed that of PM. The ultimate tensile strength of the test sample grown from single crystal substrate has surpassed 6% of that of grown from the stainless steel substrate, at the same time the plastic elongation surpassed 40%. The relative density of the sample has reached as high as 97.4% of fully dense. The mean micro hardness has reached HV496.3. The fractography of the fracture section of the tensile sample was characteristic of dimple typically which indicated that the fracture belong to ductilefracture.