The influence of Nb in the transformation behavior of ultra‐high‐strength pearlitic steels is studied. The phase transition temperature is measured by thermal simulation device, and the continuous cooling transformation curve is established. Results show that with addition of Nb, the equilibrium transformation temperature of the test steel increases, and both size of the original austenite, pearlite colonies and pearlite lamellar spacing are refined. Pearlitic transformation mechanism has changed by the addition of Nb through the interaction of solid solution and precipitation. Nb microalloy delays the beginning and ending point of pearlite transformation when the cooling rate is greater than 1.00 and 0.10 °C s⁻¹, respectively. In contrast, the transformation point is advanced when the cooling rate is less than 0.50 and 0.05 °C s⁻¹. This variation is mainly due to the morphology and distribution of Nb‐containing precipitates at different cooling rates.

中文翻译：

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Nb微合金化下2000 MPa超高强度钢丝的超细珠光体转变行为

研究了铌对超高强度珠光体钢相变行为的影响。用热模拟装置测量相变温度，建立连续冷却相变曲线。结果表明，添加Nb可使试验钢的平衡转变温度升高，原始奥氏体的尺寸，珠光体的菌落和珠光体的层状间距均得到改善。通过固溶与沉淀作用的相互作用，Nb的加入改变了珠光体相变机理。当冷却速率大于1.00和0.10°C s ^-1时，Nb微合金会延迟珠光体转变的起点和终点， 分别。相反，当冷却速率小于0.50且0.05℃s ^-1时，转变点前进。这种变化主要是由于不同冷却速率下含Nb的沉淀物的形态和分布所致。