Data for: Evolution of substructure in low-interstitial martensitic stainless steel during tempering

The evolution of the substructure and the distribution of interstitial elements in lath martensite during tempering in soft martensitic stainless steel X4CrNiMo16-5-1 was studied with line profile analysis of diffractograms from energy dispersive synchrotron X-ray diffraction, local chemical analysis with atom probe tomography and orientation mapping with electron backscatter and transmission Kikuchi diffraction. Martensite formation occurred below 135 °C without auto-tempering and led to a dislocation density in martensite of 3.8∙10^15 m^(-2), as determined from X-ray line profile analysis. On tempering carbon and nitrogen segregated to low-angle and high-angle grain boundaries. Recovery commenced above 550 °C and led to a reduction in dislocation density to a steady value of 4∙10^14 m^(-2) at 600 to 750 °C. Further tempering led to a second increase in dislocation density at room temperature, owing to the transformation of reverted austenite, formed above 650 °C, into martensite, on cooling. It was observed that the recovery of martensite competes with the formation of reverted austenite. The interpretation of the coherently diffracting domain size obtained from X-ray line profile analysis was critically discussed in the context of the internal structure in martensite.针对软马氏体不锈钢X4CrNiMo16-5-1回火过程中板条马氏体的亚结构演化与间隙元素分布，本研究采用同步辐射能量色散X射线衍射（energy dispersive synchrotron X-ray diffraction）的衍射线形轮廓分析、原子探针断层扫描（atom probe tomography）的局域化学成分分析，以及电子背散射衍射（electron backscatter diffraction）与透射菊池衍射（transmission Kikuchi diffraction）的取向成像技术开展研究。该钢的马氏体转变发生于135℃以下且无自回火现象，经X射线衍射线形轮廓分析测定，马氏体中的位错密度可达3.8×10^15 m^-2。回火过程中，碳与氮元素会偏聚至低角度与高角度晶界处。马氏体回复过程始于550℃以上，在600~750℃区间内，位错密度降低至4×10^14 m^-2的稳态值。进一步回火后，由于650℃以上形成的逆转变奥氏体在冷却过程中再度转变为马氏体，室温下位错密度会出现第二次上升。研究发现，马氏体回复过程与逆转变奥氏体的形成存在竞争关系。本文还针对由X射线衍射线形轮廓分析得到的相干衍射畴尺寸，结合马氏体内部结构展开了批判性讨论。