Fracture toughness of China low activation martensitic (CLAM) steel at room temperature

•The fracture toughness of CLAM steel at room temperature is 417.9 kJ/m2 measured by unloading compliance method according to the ASTM E1820-11.•The fracture toughness of CLAM steel at room temperature can be calculated on the basis of the fractal dimensions measured under plane strain conditions. The calculated result and relative error for this experiment are 454.6 kJ/m2 and 8.78% respectively.•The calculation method could be used to estimate the fracture toughness of materials with analysis of the fracture surface.

The fracture toughness (JIC) of China low activation martensitic (CLAM) steel was tested at room temperature through the compact tension specimen, the result is 417.9 kJ/m2, which is similar to the JLF-1 at same experimental conditions. The microstructural observation of the fracture surface shows that the fracture mode is a typical ductile fracture. Meanwhile, the fracture toughness is also calculated on the basis of the fractal dimension and the calculated result is 454.6 kJ/m2, which is consistent well with the experimental result. This method could be used to estimate the fracture toughness of materials by analyzing of the fracture surface.