三联熔炼GH4151合金Φ508 mm铸锭组织及成分均匀性

Microstructure and Composition Uniformity of Triple-Melted Φ508 mm Ingot of GH4151 Superalloy

摘要:

GH4151是一种用于航空发动机涡轮盘制造的新型变形高温合金，该合金强化元素含量高、凝固行为复杂、且开裂倾向大，大规格铸锭生产困难。本研究采用三联熔炼工艺制备了2 t级Φ508 mm规格GH4151合金铸锭，分析了其凝固组织，评价了铸锭的成分均匀性。工业级实验结果表明：所试制铸锭无开裂缺陷，铸锭边部至心部的二次枝晶间距分别为80和 150 μm；头尾横截面内成分均匀性良好，Co、Cr、W、Mo等元素的极差在0.05wt%以内，Nb元素极差在0.07wt%以内；轴向上由于元素烧损造成了Al和Ti极差较大；铸锭经均匀化后，主元素偏析系数可控制在0.8~1.2；通过快锻制备了Φ300 mm规格棒材，棒材组织、性能、探伤均能满足相关技术标准，验证了所制备的铸锭冶金质量良好。

Abstract:

GH4151 is a new type of wrought superalloy used for aero-engine turbine discs. This superalloy has high-content strengthening elements, complex solidification behavior, and high cracking tendency, making it difficult to produce ingots with large size. In this study, the 2-ton GH4151 superalloy ingot with a diameter of 508 mm was prepared by the triple melting process. The solidification microstructure of the ingot was analyzed, and the composition uniformity of the ingot was evaluated. Industrial experiment show that a crack free ingot can be obtained, and the secondary dendrite arm spacings from the ingot edge to the center are 80 and 150 μm, respectively. The composition at the top and bottom of the ingot shows a good uniformity in transverse sections. The range of elements Co, Cr, W, and Mo is within 0.05wt%, and the range of the element Nb is lower than 0.07wt%. However, the variation for Al and Ti are relatively large, due to the melting loss in the axial direction. After homogenization, the segregation coefficients of the alloying elements can be controlled between 0.8 and 1.2. Superalloy bars with a diameter of 300 mm were prepared through free forging. The microstructure, properties, and flaw detection of the bars can meet the technical requirements, verifying that the prepared ingot has satisfactory metallurgical quality.