Technique for evaluating fracture toughness in structural materials under torsion

Proposed is a method for evaluating fracture toughness of materials in articles under torsion in the presence of surface spiral concentrators of stress. The technique provides the use of quintuple cylindrical samples With the depth of spiral concentrator of stresses of 01 D and the D length, where D is an external diameter of a sample. The new technique is tested on the 45KhN2MFA steel, on cylindral samples under torsion and on the beam rectangular samples under the condition of four-point bending. A satisfactorily coincidence of the data on fracture toughness is noted