热等静压对一种激光增材制造镍基高温合金组织与性能的影响

Effect of Hot Isostatic Pressing on Microstructure and Properties of a Laser Additive Manufacturing Nickel-Based Superalloy

以ZGH451合金为研究对象,利用OM、SEM、EBSD等手段研究了热等静压前后的微观组织和力学性能。结果表明,经热等静压工艺处理后,ZGH451合金试样熔池消失,微观组织仍为柱状晶,晶粒尺寸和方向基本和沉积态试样保持一致,未出现再结晶和晶粒长大现象。合金显微缺陷大量减少,微孔体积分数由0.226 5%下降至0.000 512 5%,有效直径由80μm下降至13.5μm。随着热等静压处理温度的升高,位错密度逐渐降低。经热等静压工艺处理后,残余应力从拉应力变为压应力,抗拉强度未发生明显改变;维氏硬度和断后拉伸率大幅上升,HIP1180工艺处理的ZGH451合金维氏硬度从HV 411上升至HV 430,增加了4.7%;断后伸长率提高了35.29%。经过合适的热等静压工艺处理后,使ZGH451合金获得了良好的拉伸性能。

ZGH451 alloy was used as the research object to study the microstructure and mechanical properties before and after hot isostatic pressing by OM,SEM,EBSD and other methods.The results show that after hot isostatic pressing treatment,the molten pool of ZGH451 alloy specimen disappears,and the microstructure is still columnar crystal,whose grain size and direction are basically consistent with the sedimentary sample,and there is no recrystallization and grain growth.The microscopic defects of the alloy were greatly reduced,making the microporous volume fraction decreased sharply from 0.2265%to 0.0005125%,and the effective diameter decreased from 80μm to 13.5μm,and the dislocation density gradually decreases with the increasing of hot isostatic pressing treatment temperature.The residual stress changed from tensile stress to compressive stress,and the tensile strength had not changed significantly.The Vickers hardness of ZGH451 alloy treated by HIP1180 process increased from Hv 411 to Hv 430,an increase of 4.7%.The elongation after breaking was increased by 35.29%.The above results proved that better tensile properties of ZGH451 alloy had been obtained after suitable hot isostatic pressing process.