During the solidification of steel, phosphorus strongly segregates in the interdendritic liquid phase. In the continuous casting process, even low levels of P may have a detrimental effect on the final product quality. However, phosphorus is partly added up to 0.10 wt pct to improve the mechanical properties of advanced steel grades nowadays, e.g., High-Strength Interstitial-Free (HSIF). To provide new experimental data for the development of thermodynamic databases and solidification models for P alloyed steel grades, phase equilibria in the Fe-P and Fe-C-P key systems were studied up to 1550 °C using differential scanning calorimetry (DSC) and high temperature laser scanning confocal microscopy (HT-LSCM). Special focus was placed on solid/liquid equilibrium temperatures in the Fe-rich part of the binary Fe-P system between 0.025 and 9 wt pct P. In the ternary system, three isoplethal sections with 0.10 mass pct. P, 0.20 mass pct. C and constant mass percent ratio P/C of 2 were investigated. In the latter section, HT-LSCM observations were linked with DSC signals to optically identify present phase stabilities. Particularly at [pct P] < 1, significant differences between performed measurements and calculated phase equilibrium temperatures using thermodynamic assessments from the literature were identified. In all ternary sections, the experiments indicate less influence of P on the hypo-peritectic range compared to the thermodynamic calculations.

在钢的固化过程中，磷在树突间液相中强烈偏析。在连铸过程中，即使P含量低也可能对最终产品质量产生不利影响。但是，部分磷的添加量不超过0.10 wt％，以改善当今先进钢种的机械性能，例如，高强度无间隙（HSIF）。为开发P合金钢热力学数据库和凝固模型提供新的实验数据，使用差示扫描量热法（DSC）和高温研究了Fe-P和Fe-CP关键系统中的相平衡，温度高达1550°C激光扫描共聚焦显微镜（HT-LSCM）。特别关注的是二元Fe-P系统中富铁部分的固/液平衡温度在0.025至9 wt pct P之间。在三元系统中，三个等渗部分的质量分数为0.10 pct。P，0.20质量％。研究了C和恒定质量百分比P / C为2。在后一部分中，将HT-LSCM观测值与DSC信号相关联，以光学方式识别当前的相位稳定性。特别是在[pct P] <1时 使用文献中的热力学评估确定了执行的测量值与计算出的相平衡温度之间的显着差异。与热力学计算相比，在所有的三元部分中，实验表明P对下包晶区的影响较小。