TENSILE FRACTURE SURFACE CONFIGURATIONS OF A HEAT-TREATED-STEEL AS AFFECTED BY TEMPERATURE

摘要

Fractured surfaces of tensile specimens of SAE 4340 steel heat treated to various strength levels and microstructures were examined at a magnification of 20X. Measurements were made of the size of each of three types of fracture-appearance zones present on each specimen. These measurements were correlated with testing temperatures over the range of -196 to +200 C.nAnalysis of the quantitative amounts of three elements of fracture present, namely, fibrous, radial shear, and shear-lip, resulted in a descriptive explanation of the initiation and propagation of the fracture. These various modes of fracture zones change their relative size with changing testing temperature, which results in a transitional fracturing behavior in tension similar to that observed in other types of testing.