Effect of Hot Isostatic Pressing on Microstructure and Properties of a Laser Additive Manufacturing Nickel-Based Superalloy
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 0.226 5％to 0.000 512 5％,and the effective diameter decreased from 80 μm to 13.5 μm,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.
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