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通过热模拟试验,研究了相同的工艺条件下不同Nb含量管线钢的组织及性能,分析了合金元素Nb对相变温度、显微组织、显微硬度的影响。结果表明,在同样工艺条件下,随着Nb含量的增加,过冷奥氏体连续冷却相变温度降低,尤其在冷速较低时(1℃/s),相变开始温度降低约70℃,结束温度降低100℃以上,显微组织中出现明显的粒状贝氏体及针状铁素体;Nb促进低温贝氏体组织的形成,并且细化晶粒,使材料的显微硬度升高。
Through the thermal simulation test, the microstructure and properties of Nb steel with different Nb contents under the same process conditions were studied. The effects of alloying elements Nb on the phase transition temperature, microstructure and microhardness were analyzed. The results show that under the same conditions, with the increase of Nb content, the phase transition temperature of continuous cooling austenite decreases, especially at low cooling rate (1 ℃ / s), and the initial temperature of phase transformation decreases by about 70 ℃ , The end temperature decreased more than 100 ℃, obvious granular bainite and acicular ferrite in the microstructure; Nb promote the formation of low-temperature bainite, and grain refinement, so that the material increased microhardness .