选区激光熔化成形GH3536合金的高温塑性

High Temperature Plasticity of GH3536 Alloy Formed by Selective Laser Melting

研究了选区激光熔化成形的GH3536合金的沉积态以及热处理后的微观组织特征,并对比不同冷却方式对微观组织和高温拉伸性能的影响。通过不断优化GH3536打印参数可知,激光功率大会产生严重溅射问题,激光功率小会产生孔隙,确认最优功率范围在50~70 J/mm^(3),最佳打印参数为:激光输出功率为170 W,最大扫描速度为1 060 mm/s,最大扫描间隔为0.08 mm,层厚30μm,层间扫描转角67°,合金致密度可达99.97%。1 175℃保温30 min经过水冷、空冷和炉冷三种冷却方式,合金内部发生再结晶,炉冷条件下,晶界处有一定量的碳化物析出;水冷条件下,晶体内部有退火孪晶生成。通过855℃高温拉伸试验,3种冷却方式下得到的断裂拉伸率均超过25%。炉冷条件下,因为从奥氏体晶界处析出的碳化物增加了晶界,从而增加了GH3536的温度高塑性,因此拉伸率最好,达到了29%。该热处理制度有效改善了沉积态GH3536高温塑性差的问题,为航空航天器燃烧室零部件的应用提供了可靠的方案。

The deposited state and microstructure characteristics of GH3536 alloy formed by selective laser melting were investigated, and the effects of different cooling methods on microstructure and high temperature tensile properties were compared. Through continuous optimization of GH3536 printing parameters, it can be seen that high laser power will cause serious sputtering problems, and low laser power will produce pores. It is confirmed that the optimal power range is 50~70 J/mm^(3). The optimal printing parameters are: laser power is 170 W, scanning rate is 1 060 mm/s, scanning spacing is 0.08 mm, layer thickness is 30 μm, the scanning angle between layers is 67°, and the density of the alloy can reach 99.97%. After holding at 1 175 ℃ for 30 minutes, recrystallization occurs in the alloy after three cooling modes: water cooling, air cooling, and furnace cooling. Under the condition of furnace cooling, a certain amount of carbide precipitates at the grain boundary;Under the condition of water cooling, annealing twins are formed in the crystal. Through the high temperature tensile test at 855 ℃, the fracture tensile rates are obtained under the three cooling methods are more than 25%. Under the condition of furnace cooling, because the carbide precipitated at the grain boundary strengthens the grain boundary and improves the high-temperature plasticity of GH3536, the tensile rate is the best, up to 29%. The heat treatment system effectively improves the poor high-temperature plasticity of deposited GH3536, and provides a reliable scheme for the application of aerospace combustor parts.