ESDU Engineer
Issue 08
Fracture toughness values of some cast irons
Data Item No. 02016, “Fracture toughness (KIc) values of some cast irons”, is the product of an extensive review of literature, and analysis of data, relating to the fracture properties of cast irons.
The Item includes detailed descriptions of the general nature of cast irons commonly used in commercial applications (namely grey, chilled, white, malleable, ductile and compacted graphite irons), and their respective fracture characteristics. Additionally, the factors likely to influence a measured fracture toughness value for a given material are considered, as are the peculiarities experienced with fracture toughness testing of cast iron.
Fracture toughness data (both static and dynamic), and related material parameters, are quoted for more than 150 specifications of cast iron. The data fall within the temperature ranges of interest for practical applications, with the full brittle-to-ductile transition spectrum being considered for a number of ductile irons. The applicability of the Barsom Temperature Shift to ductile iron is also investigated.
Additionally, the Item contains an in-depth statistical analysis, offering the user two methods for obtaining a design allowable fracture toughness value with a prescribed level of confidence. The first method is the result of studies of the correlation between the fracture toughness of various forms of cast iron and other parameters: hardness (white and grey cast irons), tensile strength (grey cast iron), and temperature (ductile iron).
The second method is based on the provision of mean fracture toughness values for each type of material, from which design allowable values can be calculated. A worked example illustrates the implementation of these techniques, and guidance is given on the applicability of each method.
It is hoped that the Item will prove indispensable, both as a source of data and as a general reference, to anybody with an interest in the fracture properties of cast irons.
This Data Item was written by Senior Engineer Richard Sayers. He can be contacted at rsay@esdu.com