Abstract In-situ Small-Angle Neutron Scattering (SANS) is used to determine the time evolution of the chemical composition of precipitates at 650 °C and 700 °C in three micro-alloyed steels with different vanadium (V) and carbon (C) concentrations. Precipitates with a distribution of substoichiometric carbon-to-metal ratios are measured in all steels. The precipitates are initially metastable with a high iron (Fe) content, which is gradually being substituted by vanadium during isothermal annealing. Eventually a plateau in the composition of the precipitate phase is reached. Faster changes in the precipitate chemical composition are observed at the higher temperature in all steels because of the faster vanadium diffusion at 700 °C. At both temperatures, the addition of more vanadium and more carbon to the steel has an accelerating effect on the evolution of the precipitate composition as a result of a higher driving force for precipitation. Addition of vanadium to the nominal composition of the steel leads to more vanadium rich precipitates, with less iron and a smaller carbon-to-metal ratio. Atom Probe Tomography (APT) shows the presence of precipitates with a distribution of carbon-to-metal ratios, ranging from 0.75 to 1, after 10 h of annealing at 650 °C or 700 °C in all steels. These experimental results are coupled to ThermoCalc equilibrium calculations and literature findings to support the Small-Angle Neutron Scattering results.

中文翻译：

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钒微合金钢原位 SANS 退火过程中析出物成分的演变

摘要 原位小角中子散射 (SANS) 用于确定三种不同钒 (V) 和碳 (C) 微合金钢在 650 °C 和 700 °C 时析出物化学成分的时间演变。浓度。在所有钢中都测量了具有亚化学计量碳金属比分布的沉淀物。沉淀物最初是亚稳态的，具有高铁 (Fe) 含量，在等温退火过程中逐渐被钒取代。最终达到沉淀相组成的平台期。由于在 700 °C 时钒扩散速度更快，因此在所有钢中都可以在较高温度下观察到沉淀物化学成分的更快变化。在两种温度下，由于更高的析出驱动力，向钢中添加更多的钒和更多的碳对析出物成分的演变具有加速作用。将钒添加到钢的标称成分中会导致更多的富钒沉淀物、更少的铁和更小的碳金属比。原子探针断层扫描 (APT) 显示，所有钢在 650 °C 或 700 °C 下退火 10 小时后，都存在碳金属比分布范围为 0.75 到 1 的沉淀物。这些实验结果与 ThermoCalc 平衡计算和文献结果相结合，以支持小角度中子散射结果。将钒添加到钢的标称成分中会导致更多的富钒沉淀物、更少的铁和更小的碳金属比。原子探针断层扫描 (APT) 显示，所有钢在 650 °C 或 700 °C 下退火 10 小时后，都存在碳金属比分布范围为 0.75 到 1 的沉淀物。这些实验结果与 ThermoCalc 平衡计算和文献结果相结合，以支持小角度中子散射结果。将钒添加到钢的标称成分中会导致更多的富钒沉淀物、更少的铁和更小的碳金属比。原子探针断层扫描 (APT) 显示，所有钢在 650 °C 或 700 °C 下退火 10 小时后，都存在碳金属比分布范围为 0.75 到 1 的沉淀物。这些实验结果与 ThermoCalc 平衡计算和文献结果相结合，以支持小角度中子散射结果。