Microstructure and fracture behaviour of flash butt welds between dissimilar steels

摘要

Flash butt welds between high carbon steel and chrome-nickel steel were studied in this article. Light and electron microscopic studies have shown that the welded joints have a complex structure consisting of several phases. In addition to pearlite colonies, austenite microvolumes and regions of high strength martensite, the welds contain brittle inclusions of titanium sulphide and carbide particles. The mechanical behaviour of the welded joints is negatively influenced by the dramatic change in hardness in the weld zone. Fractographic analysis of dynamically fractured welds between carbon steel and stainless steels has shown that the fracture in the weld samples occurs in both steels. This behaviour of the material is caused by the non-uniform distribution of martensitic regions within the weld. The formation of martensitic regions in the structure of the material is a major cause of the reduction in the fatigue crack resistance of the welded joints.