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在位错型低碳马氏体中观察到孪晶亚结构已有一些报导,但是低碳位错马氏体中孪晶的形成原因、形貌特征与影响因素尚未深入研究。本文研究了Ms温度260—430℃五种低碳马氏体中李晶的形态、数量与形成原因。试验取用的最高淬火速率为11280℃/秒,五种材料均存在含有孪晶的马氏体数量(简称孪晶数量)随淬火速率增加递增的变化规律,其中M_s温度最高的20钢低于一定淬火速率时孪晶消失。淬火速率相同时,孪晶数量随Ms温度降低而增加。李晶的形态随Ms温度及化学成分变化,Ms温度高于300℃低碳马氏体(20,15MnB、18CrMnTi,18Cr_2Ni4W)中存在的少量孪晶一般是位错马氏体中的局部孪晶,孪晶往往沿板条界分布,孪晶短而厚呈笋状或透镜状(见图)。Ms温度低于300℃的25SiMn_2CrNiMoV的弯晶细长平直呈典型的孪晶形态,而且往往
The existence of twin sub-structures in dislocation-type low-carbon martensite has been reported. However, the reason for formation of twins in low-carbon dislocation martensites, the morphological features and the influencing factors have not been studied in depth. In this paper, the morphology, amount and formation of Li Jing in five kinds of low-carbon martensite with Ms temperature of 260-430 ℃ were studied. The highest quenching rate of 11280 ℃ / s for the test and taking advantage of the fact that the number of martensite containing twins (referred to as twins) increased with increasing quenching rate. Twins must quench at a certain rate. When the quenching rates are the same, the number of twins increases with decreasing Ms temperature. The morphology of Li Jing varies with the Ms temperature and chemical composition. The small amount of twins present in Ms martensite (20, 15MnB, 18CrMnTi, 18Cr_2Ni4W) with Ms temperature higher than 300 ℃ are generally local twins in dislocation martensite , Twins are often distributed along the slab boundary, twins are short and thick bamboo shoots or lenticular (see photo). The curved crystal of 25SiMn_2CrNiMoV with Ms temperature lower than 300 ℃ has a typical twin shape and often