Analysis on the Fracture Surface of Cold Forging Die Set Using the X-Ray Fractography

Abstract

The residual stress and the integral breadth on the fracture surface of cold forging die set made from heat treated high-speed steel were investigated by using the X-ray microbeam stress measurement technique.
The results obtained are summarized as follows;
1) In the region of crack initiation, the maximum compressive residual stress existed. The residual stress on the fracture surface changed from compressive to tensile according to the increase of crack length from the surface. The residual stress on the brittle fracture surface was tensile.
2) The X-ray microbeam fractographic technique gives us essential understanding of fatigue of high strength steel. This technique is applicable to the defect analysis of industrial products and thus useful in many areas.