Role of dislocation characteristics on deformation behavior of martensitic steel analyzed by neutron diffraction

抄録

The deformation behavior of lath martensite has been extensively explored, with this study focusing on its characteristics through the lens of dislocation theory. We conducted an in-situ neutron diffraction study to investigate the tensile deformation behavior of ultra-low carbon Fe–18Ni alloy under different heat treatment conditions. These alloys were initially quenched and then tempered at 573 K and 773 K. This study aimed to quantitatively evaluate dislocation characteristics and understand their role in the resulting stress–strain curves. To achieve this, we applied the convolutional multiple whole profile (CMWP) method, which determines the microstructural parameters from diffraction line profiles, linking macroscopic deformation behavior with quantitative information on dislocation characteristics without relying solely on local information. The CMWP method evaluates the dislocation characteristics, such as density, arrangement, and character. Our findings revealed that a high dislocation density in the quenched state, which gradually decreased with increasing tempering temperature, affected the mechanical properties such as the tensile strength. Additionally, we closely monitored also changes in the arrangement and character of dislocations as tempering temperature increased and during deformation. The parameters played a crucial role in revealing the evolution of flow stresses.