Effect Of Heat Treatment Process On The Microstructure And Property Of Ni-18Fe-16Cr Alloy

Nickle-base superalloy occupys an important place in the field of hightemperature structural alloy. The study of influence in structure and mechanicalproperty from alloy composition，thickness and heat treatment process could offerreliable theory basis. The aim of this paper is to study and analysis the castmicrostructure of Ni-18Fe-16Cr nickle-base superalloy，then analysis the caststructure and mechanical property in the process of heat treatment to set the bestheat treatment process， and study effect of different wall thickness to theNi-18Fe-16Cr alloy after added1.5wt%Mo element.The paper analysis and study the cast microstructure and mechnical propertyby X-ray nondestructive testing technology，XRD，metalloscope polarized light，SEM，energy spectrum analysis，software analysis and so on. At the same time，strength and hardness are tested by mechanical properties testing instruments. Afterthese, the study does different heat treatment process, and analysises the change inthe whole process.The results find that the cast microstructure of this alloy is equiaxed dentrite orcolumnar dentrite and it involves microsegregation. The grain size，SDAS andprecipitated phase increase as the wall thickness adding in the range of1.5~15mm，but the hardness and tensile property reduce. The grain size increases most quicklywhen the wall thickness changes in the range of3~6mm, but the rate slow when thewall thickness passes7mm. The SDAS increases most quickly when the wallthickness changes in the range of2~6mm, but the rate slow when the wall thicknesspasses7mm. The precipitated phase increases most quickly when the wall thicknesschanges in the range of1.5~7mm. There are γ phase，γ′phase and Laves phase inthe cast condition. The hardness，strength of extension yield strength and elongationrate improve7.93%，6.68%，8.72%，12.04%respectively when add1.5wt%Mo tothe Ni-18Fe-16Cr alloy. It has find the Laves phase could not enter into matrixcompletely when the time of solution treatment is1h or1.5h. The mechnicalproperty is best when the time of middle treatment is1h. The most reasonable heattreatment process is：1010℃×1h，AC�'985℃×1h，AC�'680℃×20h，AC. Themicrosegregation，dentrite and the bulky γ′phase and Laves phase eliminate. The hardness，strength of extension and yield strength improve28.26%、33.71%、18.43%respectively after heat treatment.