Influence of Powder Characteristics on the Microstructure and Mechanical Behaviour of GH4099 Superalloy Fabricated by Electron Beam Melting

文献类型： 外文期刊

第一作者： Wang, Shixing

作者： Wang, Shixing;Wang, Shixing;Tao, Shen;Peng, Hui;Peng, Hui

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关键词： Ni-based superalloys; electron beam melting; additive manufacturing; Argon gas atomized; plasma rotation electrode process; powder characteristics

期刊名称：METALS （ 影响因子：2.695； 五年影响因子：2.758 ）

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年卷期： 2022 年 12 卷 8 期

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收录情况： SCI

摘要： A Chinese superalloy, GH4099 (similar to 20 vol.% gamma' phase), which can operate for long periods of time at temperatures of 1173-1273 K, was fabricated by electron beam melting (EBM). Argon gas atomized (GA) and plasma rotation electrode process (PREP) powders with similar composition and size distribution were used as raw materials for comparison. The microstructure and mechanical properties of both the as-EBMed and post-treated alloy samples were investigated. The results show that the different powder characteristics result in different build temperatures for GA and PREP samples, which are 1253 K and 1373 K, respectively. By increasing the building temperature, the EBM processing window shifts towards a higher scanning speed direction. Microstructure analysis reveals that both as-EBM samples show a similar grain width (measured to be similar to 200 mu m), while the size of gamma' precipitated in the PREP sample (similar to 90 nm) is larger than that of the GA sample (similar to 130 nm) due to the higher build temperature. Fine spherical gamma' phase precipitates uniformly after heat treatment (HT). Furthermore, intergranular cracking was observed for the as-fabricated PREP sample as a result of local enrichment of Si at grain boundaries. The cracks were completely eliminated by hot isostatic pressing (HIP) and did not re-open during subsequent heat treatment (HT) of solution treatment and aging. The tensile strength of the PREP sample after HIP and HT is similar to 920 MPa in the building direction and similar to 850 MPa in the horizontal direction, comparable with that of the wrought alloy.

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