Pan Tao,Zhang Huaxia,Ma Xiuping,et al.Microstructure and Mechanical Properties of K465 Superalloy Prepared by Cold Crucible Levitation Melting[J].Special Steel,
Pan Tao,Zhang Huaxia,Ma Xiuping,et al.Microstructure and Mechanical Properties of K465 Superalloy Prepared by Cold Crucible Levitation Melting[J].Special Steel,DOI:.
Microstructure and Mechanical Properties of K465 Superalloy Prepared by Cold Crucible Levitation Melting
The cold crucible levitation melting (CCLM) technology uses a water-cooled copper crucible instead of a refractory crucible as the melting container, which can effectively solve the problem of corrosion of the crucible by the high temperature melt, and is suitable for the preparation of ultra-high purity metal materials. In this work, the K465 nickel-based cast superalloy is prepared by CCLM technology. When the vacuum level in the melting chamber is lower than 0.01 Pa, high-purity argon gas is introduced to start smelting. After the metal raw materials are completely melted, refining is performed for 10 minutes. The results of the chemical composition test indicate that the contents of the main elements in the alloy fully meet the standard compositional requirements and the compositional uniformity is excellent. The impurity contents of oxygen
w
[O] and nitrogen
w
[N] in the alloy are both controlled at 0.000 3%, while the sulfur
w
[S] content is as low as 0.000 049%. The microstructure of the as-cast alloy primarily consists of
γ matrix phase, γ ′ strengthening phase, (γ + γ ′) eutectic phase, as well as bulk and strip-shaped carbides enriched in titanium (Ti), tungsten (W), niobium (Nb), and molybdenum (Mo), which is consistent with the microstructural characteristics of the alloy prepared by vacuum induction melting (VIM). Mechanical property tests demonstrate that the K465 superalloy prepared by CCLM exhibits a room-temperature tensile strength exceeding 1 000 MPa and an elongation above 5%. Moreover, the high temperature rupture life of alloy achieves more than 45 h under the service condition of 975 ℃ and 225 MPa. The research results show that the cold crucible levitation melting technology can prepare high-purity K465 nickel-based cast superalloy, which has excellent mechanical properties. This study provides an innovative technical approach for the melting of ultra-high purity superalloys.
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