Abstract: Forming process and microstructure and high temperature tensile properties of selective laser melted GH3536 superalloy under different cooling methods and heat treatments were investigated. The results show that the porosity of the alloy decreases first and then increases on the whole with the increase of laser power. The porosity increases with the increase of scanning speed under the lower laser power, while the porosity first decreases and then increases with the increase of scanning speed under the higher laser power. The density of the alloy is over 99.8% when the scanning distance is 0.11 mm. The optimized forming process is laser power of 285 W, scanning speed of 960 mm/s and scanning distance of 0.11 mm. The slower is the cooling rate after heating at 1175 ℃ for 1 h, the higher is the high temperature elongation of the alloy after the heat treatment. During furnace cooling, the continuous carbide precipitates at the grain boundary, which increases the grain boundary strength and the high temperature plasticity. Solution treated at 1200 ℃ after hot-isostatic pressing, the grain size of the alloy is uniform, and the coarse and discontinuous carbides at the prior grain boundary become continuous and uniform, which makes the high temperature elongation in both transverse and longitudinal directions reach more than 36%.

Key words: laser selective melting, GH3536 superalloy, microstructure, high temperature tensile properties