Abstract: The effect of solidified structure characteristics on heat-treated structures and rupture properties was studied in CMSX-2 single crystals with different arm spacing. The results show that,refining of solidified structures enhances the uniform degree of alloy structures,then improves the starting melting temperature of superalloy during solution treatment efficiently. In addition,structure refining can improve effect of heat treatment on rupture properties. The positive effect of superfining of solidified structures on mechanical properties of CMSX-2 superalloy is affirmed sufficiently by the experiment result in which the rupture lives of superfine dendrite single crystals are about 1.45 and 1.85 times those of the coarse dendrite single crystals respectively,in as-cast and heat-treatment condition.
Effect of structure refining on heat-treated structures and mechanical properties in single crystal superalloy
Abstract:
The effect of solidified structure characteristics on heat treated structures and rupture properties was studied in CMSX 2 single crystals with different arm spacing. The results show that, refining of solidified structures enhances the uniform degree of alloy structures, then improves the starting melting temperature of superalloy during solution treatment efficiently. In addition, structure refining can improve effect of heat treatment on rupture properties. The positive effect of superfining of solidified structures on mechanical properties of CMSX 2 superalloy is affirmed sufficiently by the experiment result in which the rupture lives of superfine dendrite single crystals are about 1.45 and 1.85 times those of the coarse dendrite single crystals respectively, in as cast and heat treatment condition.
Table 3 Characteristics of heat-treated structures in coarse dendrite, fine dendrite and superfine dendrite single crystals
Heat-treated condition
Structures
λ1=250?μm
λ1=80?μm
λ1=35?μm
1?280?℃/1?h, A.C.+ 1?080?℃/4?h, A.C.+ 870?℃/20?h, A.C.
Segregation1
Obvious
Obvious
Obvious
γ′ size2
Not even
Not even
Not even
Eutectic3
Existence and more
Existence
Existence
1?315?℃/1?h, A.C.+ 1?080?℃/4?h, A.C.+ 870?℃/20?h, A.C.
Segregation1
Existence
Existence
Existence
γ′ size2
Almost even, 0.5?μm
Even, 0.5?μm
Even, 0.5?μm
Eutectic3
Existence
Existence and few
Nonexistence
1?330?℃/1?h, A.C.+ 1?080?℃/4?h, A.C.+ 870?℃/20?h, A.C.
Segregation1
Not obvious
Not obvious
Nonexistence
γ′ size2
Almost even, 0.5?μm
Even, 0.5?μm
Even, 0.45?μm
Eutectic3
Existence
Nonexistence
Nonexistence
1. “Obvious”: dendrite can be seen clearly on OM; “Not obvious”: dendrite can be seen faintly on OM; “Existence”: dendrite can be seen on OM.2. “Even” refer as the comparison of γ′ sizes between dendrite core and inter-dendrite area.3. “Existence and more”: eutectic can be often found on OM; “Existence”: eutectic can not be often found on OM; “Existence and few”: eutectic can be found seldom on OM only.