AI 中文总结
研究疲劳珠光体钢应变弛豫，用暗场X射线显微镜原位观察，发现渗碳体薄片抑制长程位错运动，应变图有明显弛豫，归因于薄片间位错短程湮灭，将晶粒尺度应变恢复与宏观软化联系起来。
AI 中文摘要
珠光体钢是铁路车轮和轨道的首选材料，其层状铁素体-渗碳体结构平衡了成本、强度和耐磨性。然而，在使用中，循环载荷与摩擦热会使钢软化，促进疲劳并最终导致失效。在此，我们使用暗场X射线显微镜（DFXM）对疲劳珠光体菌落进行原位跟踪，直至550°C退火。取向图显示晶格旋转可忽略不计，且无亚晶胞形成，表明渗碳体薄片抑制了长程位错运动。应变图显示出明显的弛豫：弹性应变扩展变窄近40%，恢复在250°C以下开始，处于铁路车轮的工作温度范围内。我们将这种弛豫归因于薄片间位错的短程湮灭，将晶粒尺度的应变恢复与服役中珠光体铁路钢的宏观软化联系起来。
英文摘要
Pearlitic steels are the material of choice for railway wheels and rails, where their lamellar ferrite-cementite structure balances cost, strength, and wear resistance. However, in use, cyclic loading combined with frictional heat softens the steel, promoting fatigue and eventual failure. Here we use Dark-Field X-ray Microscopy (DFXM) to follow, operando, the grain-scale response of a fatigued pearlitic colony during annealing up to 550 °C. Orientation maps reveal negligible lattice rotation and no sub-cell formation, indicating that the cementite lamellae suppress long-range dislocation motion. Strain maps nonetheless show pronounced relaxation: the elastic strain spread narrows by nearly 40%, with recovery starting below 250 °C, within the operating temperatures of railway wheels. We attribute this relaxation to short-range annihilation of dislocations confined between lamellae, linking grain-scale strain recovery to the macroscopic softening of pearlitic railway steels in service.
