新型镍基GH4198合金微观组织及热处理性能调控

Microstructure and Heat Treatment Performance Control of Novel GH4198 Superalloy

摘要:

采用电子探针、金相显微镜和场发射扫描电镜等手段研究了固溶热处理制度对新型GH4198合金微观组织和性能的影响规律。结果表明，随着固溶温度从1100 ℃增加至1150 ℃，一次γ′相回溶至基体，晶粒从ASTM9.5级长大至3级，同时二次γ′相尺寸增加；拉伸性能受固溶温度影响较大，当固溶温度从1120 ℃增加至1140 ℃时，750 ℃及以下温度拉伸强度下降，而850 ℃拉伸性能达到最优。亚固溶温度1120 ℃热处理时，随着固溶冷却速率从10 ℃/min增加至450 ℃/min，一次γ′相体积分数和尺寸保持不变，二次γ′相尺寸减小，显微硬度增加，并讨论了相关的强化机制。

Abstract:

The microstructure and properties of the novel GH4198 alloy were studied under various solution heat treatment regimes using advanced characterization techniques such as electron probe microanalysis, metallographic microscopy, and field emission scanning electron microscope. The results indicate that as the solution temperature increases from 1100 °C to 1150 °C, the primary γ' phase dissolves into the matrix, the grain size increases from ASTM 9.5 to 3, and the size of the secondary γ' phase increases. The tensile properties are greatly affected by the solution temperature: the optimum tensile strength is obtained at 850 °C and low-temperature tensile strength drops when the solution temperature increases from 1120 °C to 1140 °C. At the sub-solvus temperature of 1120 °C, as the solution cooling rate increases from 10 °C/min to 450 °C/min, the volume fraction and the size of the primary γ' phase remain unchanged, the size of the secondary γ' phase decreases, and the microhardness increases. The possible explanations for the improvement of mechanical properties are also discussed.