Classification of steels according to their sensitivity to fracture using a synergetic model

To select a rational method for cutting of rolled stocks made from materials with different physical and mechanical properties, an engineer must have the tools to make such a choice. In order to find the most informative system of fracture criteria allowing to classify materials authentically by their fracture sensitivity, the software was developed. It allows to solve the clustering problem in a multidimensional space of parameters and present the obtained information in a visual form using self-organizing Kohonen maps. The cluster analysis of the material fracture criteria was carried out. The most informative criterion among the ones characterizing the mechanical properties of steels is the «offset yield strength», among the synergistic ones – «scale criterion». At the same time, among the traditional mechanical features of steels, a set allowing to classify materials with a given integrity by their cutting sensitivity has not been found. It was established that the fracture criteria: «crack growth criterion» and «brittleness criterion» are basic informative features. When adding any of the remaining complex criteria («crack nucleation criterion» or «scale criterion»), they form the most informative sets of minimal power, providing the classification of materials by their cutting sensitivity with a given integrity. In order to obtain high-quality workpieces at a minimum conversion cost, recommendations were developed for choice of the method for cutting of rolled stocks in magnitude of criteria values: «crack growth criterion» and «brittleness criterion». To cut materials «in plastic state», the cutting by shear should be used, specifically—a closed cutoff scheme or an incompletely closed cutoff scheme with an active transverse clamp or a cutoff scheme with a differentiated clamp of rolled stocks. If increased requirements are imposed on the geometric accuracy of the workpieces, it is recommended to use complex blanking and cutting processes. For cutting materials «in elastoplastic state» there are good reasons to use the cutting by shear, and in particular—an incompletely closed cutoff scheme with an active and passive transverse clamp. Closer to the class interval, it is possible to apply breaking by bending with the application of an effective stress concentrator. Breaking by bending should be used to cut «brittle» materials. The carried out experiments confirmed the adequacy of theoretical conclusions and recommendations on the choice of a rational