激光选区熔化GH3536高温合金的成形工艺及组织性能

研究了激光选区熔化GH3536高温合金的成形工艺及不同冷却方式和热处理制度下的显微组织和高温拉伸性能。结果表明:随着激光功率的增加,合金的孔隙率整体上呈先降低后增加的趋势;当激光功率较低时,合金的孔隙率随扫描速度增加而升高;当激光功率较高时,合金的孔隙率随扫描速度增加先降低后增加;扫描间距为0.11 mm时,合金的致密度达到99.8%以上。优选成形工艺为:激光功率285 W,扫描速度960 mm/s,扫描间距0.11 mm。1175 ℃保温1 h后冷却速度越慢,热处理后合金的高温伸长率越高。炉冷时,晶界处析出连续的碳化物,使晶界强度增加,高温塑性提高。热等静压后进行1200 ℃高温固溶处理,合金的晶粒尺寸较为均匀,原晶界处粗大断续状的碳化物变得连续均匀,使合金的横纵向高温伸长率达到36%以上。

Forming process and microstructure and properties of selective laser melted GH3536 superalloy

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%.