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本文研究定向凝固K17G合金显微组织特点及其与凝固时冷却速率关系,当冷却速率在0.4～1.0℃/秒时,其尺寸、数量与冷却速率平方根成反比。热处理对显微组织和机械性能有重要影响,重新析出的细小γ′相数量与固溶温度有关,尺寸则取决于时效温度(相同时效时间)。经1220℃/4小时/空冷加900℃/16小时/空冷热处理后,760℃66公斤/毫米~2的持久寿命为300～450小时,是普通铸造K17G合金的3～4倍;持久塑性δ在15%左右,约为普通铸造合金的4倍。对蠕变过程中MC碳化物及γ-γ′共晶断裂,也作了一些探讨。
In this paper, we study the microstructure of directional solidified K17G alloy and its relationship with the cooling rate during solidification. When the cooling rate is between 0.4 ~ 1.0 ℃ / s, the size and amount are inversely proportional to the square root of the cooling rate. The heat treatment has a significant effect on the microstructure and mechanical properties. The amount of re-precipitated fine γ ’phase is related to the solution temperature, and the size depends on the aging temperature (same aging time). After 1220 ℃ / 4 hours / air cooling plus 900 ℃ / 16 hours / air-cooling heat treatment, the durable life of 66 kg / mm ~ 2 at 760 ℃ is 300 ~ 450 hours, which is 3 ~ 4 times of that of ordinary cast K17G alloy; About 15%, about 4 times the ordinary cast alloy. In the process of creep MC carbides and γ-γ ’eutectic fracture, also made some discussion.