Quantitative fractography in the DBT regime of 9Cr-1Mo ferritic/martensitic steel

In this work quantitative fractography using average dimple diameter and fractal dimensions is investigated in the ductile to brittle transition (DBT) regime of 9Cr-1Mo steel at varying strain rates. The tensile experiments were conducted at different strain rates (in range of 3x10 -4 per seconds to 18x10 -3 per seconds) and varying temperature (ranging from -20°C to -70°C). The Fractographic examinations were used to characterize the DBT regime as the features showed decreasing dimple size with increasing strain rate. The influence of strain rate was also characterized using fractal dimension of a material’s fracture surface determined by box count method. The dimple diameter and fractal dimension were in agreement with the strain rate influence.