The presented work is concerning with ductile fracture problematic under monotonic loading which is result of gradual material degradation at large plastic deformation. At present, a large number of models, which calibration is not trivial, are used for its prediction. Ductile fracture mechanisms and cut-off region are described in the literature search part. Next, there is given a summary of criteria which are based on different approaches to ductile fracture. There were proposed and used KHPS and KHPS2 criteria within this PhD thesis. Procedure of assessment of the stress-strain curve and ductile fracture criteria calibration are described in last part of the literature search. A summary of tests, which were done in order to calibrate chosen criteria, is given in experimental part. Various stress states within broad range of stress triaxiality and Lode parameter were reached using these tests. Special type of specimen, by which very low stress triaxiality value is reached, was designed within this work. All specimens were made from the steel 12 050. Wrought rods of one melt with circular cross-section of 27 mm in diameter were used as semi-product. Calibration of chosen ductile fracture criteria was performed using foregoing tests. These criteria were implemented by author into explicit finite element software ABAQUS/Explicit using user subroutine VUMAT. Chosen criteria were used for simulation of multistep extrusion at which formation of internal central cracks occurs. These criteria were also used for simulation of cutting of circular cross-section rods. Results from simulation were compared to experiments which were done by industrial partner J-VST.

The master’s thesis presents a concept for spring bush manufacturing made of 11 320-5R steel by cold forming. Five steps process of manufacturing is based on the literary studies and technical calculations. The multistage cold forming machine HATEBUR AKP 5-5 was chosen for selected option of forming technology. As raw material was used cylinder shape with diameter of 26 mm and length of 29 mm. The economic results fix the price of one component of 16 CZK for annual dose 250 000 pieces.

The project of master’s thesis elaborated within engineering studies of engineering technology deals with concept of manufacturing procedure of connecting pin made of steel 11 320 5R with cold forming. Two variants of production technique were projected based on the literature study of the cold heading and cold extrusion. Selected variant, for which the technological calculation was accomplished, consists of five forming operations. Manufacture was projected for multistage automatic forming machine TPM 8-A made by manufacturer Šmeral Brno with nominal forming force 1000 kN. Tool steel 19 436 was chosen as a material of extrusion and heading tools.