In-situ study of deformation behaviour and mechanisms occurring during early stages of deformation is of a great practical importance. Low stacking fault energy materials, as is the case of AISI 304L, show non-linear deformation characteristics way below the bulk yield point. Shockley partial dislocations, formation of stacking faults respectively, resulting in creation of shear bands and ε-martensite transformation are the mechanisms occurring in the low strains in the studied steel. Acoustic emission and infrared thermography have been used in this study to investigate the deformation kinetics at the low strain stages of slow strain rate tensile tests. Acoustic emission cumulative energy together with the tracking of specimen maximum temperature have been found to be very useful in-situ techniques both supplementing each other in the sense of the sensitivity to different mechanisms. Mechanical, acoustic emission and infrared thermography results are discussed in detail with respect to potential occurred mechanism.

Progress in the industry is accompanied by the development of new materials and more efficient technological production processes. At present, additive production is becoming very attractive in all industries (research, development, production), which brings a number of advantages compared to subtractive methods (customization, production speed, control of material properties by users, etc.). The main advantage of 3D printing is the controlled deposition of material in defined places. Instead of demanding manual labour, fully automated production via computers leads to the manufacturing of complex components from materials whose production in conventional ways would be problematic or even impossible. Because these are new technologies, the main direction of research at present is to identify the basic physical properties of these materials under different types of loading.
The main goal of this article is to observe the dependence of the behaviour of the extruded material (thermoplastic reinforced with chopped carbon fibre) on the printing parameters (thickness of the lamina, the orientation of the fibres of the printed material, etc.). Based on published scientific works, it appears that these settings have a significant impact on the achieved physical properties. This is the reason why the authors decided to analyze the influence of these parameters on the basis of processed data from experimental measurements of mechanical properties in the MATLAB program. As this is FFF printing, an essential condition is to identify and specify the directional dependence of the behavior of the printed material. This physical phenomenon is a necessary condition for gradual knowledge for the purposes of a subsequent mathematical description of the material properties. According to the authors, for the purposes of modeling these materials in FEM-based programs, it is essential to define the directional dependence in the plane of the lamina.