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利用热模拟方法并结合彩色金相和EBSD技术,分析了在线重加热速率对X80管线钢组织中M/A岛的含量和分布的影响规律。结果表明,重加热速率在一定范围内升高,能够有效延迟位错回复、增大碳原子扩散速率,促进残留奥氏体中碳的富集,有利于晶内细小M/A岛的形成。重加热速率由20℃/s升高到50℃/s的过程中,M/A岛的百分含量基本呈现单调上升趋势,其分布位置也开始由晶界为主转变为晶内、晶界同时存在,当重加热速率高于50℃/s后,M/A岛的百分含量开始呈现下降趋势,同时又以晶界分布为主,重加热速率为50℃/s时,M/A岛的含量达到峰值,呈现晶内、晶界同时分布的理想状态。
The effect of on-line reheating rate on the content and distribution of M / A island in X80 pipeline steel was analyzed by means of thermal simulation method combined with color metallography and EBSD technique. The results show that the reheating rate increases within a certain range, which can effectively delay the dislocation recovery, increase the diffusion rate of carbon atoms and promote the enrichment of carbon in retained austenite, which is in favor of the formation of fine M / A islands in the grains. When the reheating rate increased from 20 ℃ / s to 50 ℃ / s, the percentage of M / A island showed a monotonously increasing trend, and its distribution began to change from grain boundary to intragranular and grain boundary At the same time, when the reheating rate is higher than 50 ℃ / s, the percentage of M / A island begins to decrease and the grain boundary is dominated. When the reheating rate is 50 ℃ / s, M / A Island peak content, showing the crystal, grain boundary at the same time the ideal distribution.