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奥氏体的层错能在较宽的温度范围内与Fe-40Ni合金的层错能相近。含Ni的含量达到40%(质量分数,%)时,Fe-Ni合金的面心立方结构可以保持到室温而不发生相变。运用光学显微镜、透射电子显微镜(TEM)对Fe-40Ni-Ti合金在不同温度等温过程中的晶粒长大行为进行了研究,结果表明:等温150 min,从880℃到1160℃合金晶粒长大缓慢;1220℃左右时,晶粒的长大倾向可以明显观察到;当温度达到1300℃后,等温30 min晶粒迅速长大并粗化。通过透射电镜观察发现,凝固过程中形成的TiN颗粒和应变诱导析出相快速回溶到合金基体中,导致晶界迁移容易进行。利用Fe-40Ni-Ti合金奥氏体模型钢能够模拟高温时奥氏体晶粒的长大行为。
The stacking fault of austenite can be similar to that of Fe-40Ni alloy over a wide temperature range. When the Ni content reaches 40% (mass fraction,%), the face-centered cubic structure of the Fe-Ni alloy can be maintained to room temperature without phase transition. The grain growth behavior of Fe-40Ni-Ti alloy during isothermal process at different temperatures was studied by optical microscope and transmission electron microscope (TEM). The results show that the grain growth of the alloy from 880 ℃ to 1160 ℃ Large and slow; about 1220 ℃, the grain growth tendency can be clearly observed; when the temperature reaches 1300 ℃, the isothermal 30min grains grow rapidly and coarsening. It was found by TEM that the TiN particles and strain-induced precipitates formed during the solidification quickly dissolved back into the alloy matrix, resulting in easy grain boundary migration. Using Fe-40Ni-Ti alloy austenite model steel can simulate the growth behavior of austenite grains at high temperature.