淬火工艺对超高强度特厚板组织与性能的影响

Effect of quenching process on microstructure and mechanical properties of ultra-high strength heavy plate

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。

Effects of cooling rate during single and double quenching and the second quenching temperature on the core microstructure and mechanical properties of an ultra high strength heavy plate were investigated.The result shows that with a lower quenching cooling rate of0.05 ℃/s,the microstructure is mainly composed of granular bainite,with lower strength and toughness.With the increase of cooling rate,the fraction of granular bainite decreases and the martensite increases,which results in higher strength and toughness.A remarkable grain refinement of prior austenite can be obtained by double quenching,which can improve the strength and toughness.For double quenching,when the second quenching temperature is in the intercritical region,a lower toughness is obtained due to the undecomposed M/A constituents after tempering.When the second quenching temperature is in the austenite region,the toughness increases gradually with the quenching temperature,the best result occurs at 930 ℃.