Effect of Solid Solution and Aging Treatment on Microstructure and Hardness of Selective Laser Melting GTD222 Nickel-Based Alloy
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摘要: 采用选区激光熔化成形技术制备GTD222镍基合金并进行了1 150 ℃固溶和时效处理，研究了固溶处理时间（0，20，40，60，120 min）、时效温度（760，780，800，820，840 ℃）和时效时间（2，4，8 h）对显微组织和硬度的影响。结果表明：选区激光熔化成形GTD222合金中的柱状晶与成形方向呈一定倾斜角度，合金中存在胞状亚结构和高密度位错，未析出γ'相，MC碳化物主要分布于晶界及相邻亚结构界面处；经1 150 ℃固溶处理后合金中的亚结构均消失，随着固溶时间的延长，碳化物逐渐溶解，合金显微硬度先下降后趋于稳定；在760~840 ℃时效处理2~8 h后，合金基体中析出大量γ'相，γ'相的尺寸随时效时间延长和时效温度升高而增大，合金硬度则随时效时间延长和时效温度降低而增大。
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关键词:
- 增材制造 /
- 选区激光熔化 /
- GTD222镍基高温合金 /
- 显微组织 /
- 热处理
Abstract: The GTD222 nickel-based alloy was prepared by selective laser melting technique and then treated by solution at 1 150 ℃ and aging. The effects of solution treatment time (0,20,40,60,120 min), aging temperature (760,780,800,820,840 ℃) and aging time (2,4,8 h) on the microstructure and hardness of the alloy were studied. The results show that the columnar crystals in the GTD222 alloy formed by selective laser melting had a certain oblique angle to the forming direction. There were cellular substructures and high-density dislocations in the alloy, no γ' phase was precipitated, and MC carbides mainly distributed at grain boundaries and interfaces of adjacent substructures. The substructures of the alloy disappeared after solution treatment at 1 150 ℃. With increasing solution time, the carbides gradually dissolved, and the alloy hardness decreased first and then became stable. After aging at 760-840 ℃ for 2-8 h, a large number of γ' phases were precipitated in the alloy matrix. The size of γ' phase increased with aging time and temperature, while the hardness of alloy increased with increasing aging time and decreasing aging temperature. -
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