Evolution Behavior of Complex Precipitation Phases in Highly Alloyed GH4151 Superalloy
Designing high-performance aeroengine is important for development in the aviation in-dustry.One of the key components is turbine disk material that can operate at 800℃.Among various methods for strengthening alloys,increasing the alloying degree is important,and GH4151 is one of the typical alloys with a high alloying degree.It comprises a large number of refractory metal elements and γ'-forming elements.OM,SEM,and JMatPro software were used to study the sensitivity of GH4151 micro-structure evolution during heat treatment processes.The results show that a high alloying degree produc-es a complex microstructure with low-melting phases,such as Laves,γ/γ'eutectic,andηphases.Due to the difference in incipient melting temperature of each precipitated phase,a three-stage heat treatment was developed to effectively eliminate the harmful phases in the alloy.The contents of segregation ele-ments Nb and Ti in the as-cast GH4151 alloy have an obvious influence on the incipient melting tempera-ture,whereas the effect of Mo content is relatively slight,and that of W content is not obvious.Decreas-ing Ti content while increasing Nb and Mo contents could reduce the incipient melting temperature of theη phase.Furthermore,increasing Ti and Mo contents while decreasing Nb content could reduce the incipi-ent melting temperature of Laves phase.A large amount of γ'-forming elements contributes to the cooling rate sensitivity of y'phase evolution.15℃/min is the critical value for the irregular growth of the y'phase in the GH4151 alloy.When compared to alloys with low γ'-forming elements content,the γ'phase in GH4151 alloy has a larger size when the cooling rate is＞15℃/min,and exhibits an irregular shape when the cooling rate is＜15℃/min.Thus,a high alloying degree contributes to the complex and sensitive mi-crostructure evolution behavior of GH4151 alloy.
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维普
