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采用不同冷却速度的一次和两次淬火以及不同的二次淬火温度,研究了淬火工艺对超高强度调质特厚板心部组织和性能的影响。结果表明:在较低的淬火冷速(0.05℃/s)下,组织以粒状贝氏体为主,强度和韧性较低;随着冷却速度的提高,粒状贝氏体逐渐减少,马氏体增加,强度和韧性提高。两次淬火能明显细化原始奥氏体晶粒,提高钢板强韧性匹配。当二次淬火温度位于两相区时,大量回火未分解的M/A组元是造成韧性较低的主要原因;当二次淬火温度位于完全奥氏体区时,随淬火温度增加,韧性逐渐提高,在930℃时获得最佳的强韧性匹配。
The effect of quenching process on the microstructure and properties of ultra-high strength quenched and tempered extra-thick slab was studied by using one or two quenching with different cooling rates and different secondary quenching temperatures. The results show that the microstructure is dominated by granular bainite and its strength and toughness are lower at lower quenching cooling rate (0.05 ℃ / s). With the increase of cooling rate, the granular bainite gradually decreases and the martensite Increased, increased strength and toughness. Two quenching can significantly refine the original austenite grains, improve the toughness of the steel match. When the secondary quenching temperature is located in the two-phase region, a large amount of temper undecomposed M / A component is the main reason causing lower toughness; when the secondary quenching temperature is in the complete austenite region, with the quenching temperature increases, the toughness Gradually increased, at 930 ℃ get the best toughness match.