X100管线钢冲击断裂过程及止裂性分析

对不同终冷温度的X100管线钢进行了动态示波冲击试验,结合断口形貌及微观组织观察,研究了试验温度、终冷温度及组织对冲击断裂过程及止裂性能的影响.结果表明,终冷温度为400℃时,钢的裂纹形成能及扩展能较高,止裂性能良好,仅-60℃时出现少量分层;终冷温度为520℃时,随试验温度降低,裂纹形成能和扩展能逐渐降低,止裂性能逐渐下降,断口中韧窝脆性倾向增强,分层加重.冲击过程中的最大冲击载荷随试验温度的降低而近似线性增加.组织的均匀、板条边界和晶界处的膜状、细小点状M/A岛、细小析出相均有益于钢的冲击韧性及止裂性能.

Anti-crack Ability and Impact Fracture of X100 Pipeline Steel

Dynamic Charpy impact test of the X100 pipeline steel with different final cooling temperature and testing temperature was conducted. The fracture morphology and microstructure were observed. The results showed that when the final cooling temperature is 400°C, the crack formation and propagation energy maintains at a high level, anti-crack ability is good, a few layer phenomenon occurs only at -60°C. When the final cooling temperature is 520°C, the crack formation and propagation energies are reduced with the decreasing of testing temperature, the anti-crack ability decrease too, and the layer phenomenon at impact fracture is aggravated gradually. The maximal shock load is increases linearly with the testing temperature decreases. The fine and uniform microstructure and the tiny separation phases at the grain boundaries and bainitic laths are favorable to the impact toughness.