The tetragonality and carbon distribution in tempered Fe-0.6C-1Mn martensite were investigated by X-ray diffraction and atom probe tomography to elucidate strain relaxation in the tetragonal lattice during tempering and its relationship with the solubility of excess carbon in martensite. Even though tetragonality (c/a) decreased with an increase in the tempering temperature, it persisted at low levels up to 400 °C. Si addition suppressed the decrease in tetragonality at 400 °C by inhibiting recovery in the dislocated matrix. Such persistence implies that dislocation migration is crucial for the complete release of tetragonal lattice strain at such a temperature, in addition to the decrease in the amount of solute carbon in martensite. A low level of tetragonality was observed for martensite containing carbon in the solid solution below the critical value of ~ 0.2 mass pct, at which a bcc structure was predicted. The amount of solute carbon after tempering was linearly correlated with tetragonality in the solute carbon content range of 0.07 to 0.6 mass pct, and the correlation coefficient was similar to those for as-quenched auto-tempered martensite and bainitic ferrite; these results indicate that the amount of excess carbon is simply determined by the amount of tetragonal lattice distortions remaining after carbide precipitation and recovery.

通过X射线衍射和原子探针断层扫描技术研究了回火后的Fe-0.6C-1Mn马氏体的四方性和碳分布，以阐明回火过程中四方晶格中的应变弛豫及其与过量碳在马氏体中溶解度的关系。即使四方性（c / a）随回火温度的升高而降低，直到400°C时仍保持较低的水平。硅的添加通过抑制位错基体的恢复而抑制了400°C时四方性的降低。这样的持久性意味着位错迁移对于在这样的温度下完全释放四方晶格应变至关重要，除了减少马氏体中的固溶碳量之外。对于固溶体中含碳的马氏体，在低于〜0.2质量pct的临界值（观察到bcc结构）的临界值以下观察到了较低的四方性。回火后的固溶碳量与四方性在0.07至0.6质量％的固溶碳含量之间线性相关，相关系数与淬火后的自回火马氏体和贝氏体铁素体相似。这些结果表明，过量的碳量仅由碳化物沉淀和回收后剩余的四方晶格畸变量确定。