The article presents the results of the investigations performed on high manganese austenitic steel which underwent the test of uniaxial tension, with the application of electric current impulses. The application of low voltage impulse alternating current of high intensity during the plastic deformation of the examined steel caused the occurrence of the electroplastic effect, which changed the shape of the stress-strain curve. A drop of flow stress and elongation of the tested material was observed in the case of the application of electric current impulses, in respect of the material stretched without such impulses and stretched at an elevated temperature. The analysis of the morphology of the fractures showed differences between the samples tested under the particular conditions. An analysis of the alloy’s microstructure was also performed under different conditions. The application of electric current impulses can have a significant influence on the reduction of the forces in the plastic forming processes for this type of steel.
The results are based on two experimental high-manganese X98MnAlSiNbTi24-11 and X105MnAlSi24-11 steels subjected to thermo-mechanical treatment by hot-rolling on a semi-industrial processing line. The paper presents the results of diffraction and structural studies using scanning and transmission electron microscopy showing the role of Nb and Ti micro-additives in shaping high strength properties of high-manganese austenitic-ferritic steels with complex carbides. The performed investigations of two experimental steels allow to explain how the change cooling conditions after thermo-mechanical treatment of the analysed steels affects the change of their microstructure and mechanical properties. The obtained results allow assessing the impact of both the chemical composition and the applied thermo-mechanical treatment technology on the structural effects of strengthening of the newly developed steels.
The article is focused on thermomechanical and plastic properties of two high-manganese TRIPLEX type steels with an internal marking 1043 and 1045. Tensile tests at ambient temperature and at a temperature interval 600°C to 1100°C were performed for these heats with a different chemical composition. After the samples having been ruptured, ductility was observed which was expressed by reduction of material after the tensile test. Then the stacking fault energy was calculated and dilatation of both high-manganese steels was measured. At ambient temperature (20°C), 1043 heat featured higher tensile strength by 66MPa than 1045 heat. Microhardness was higher by 8HV0,2 for 1045 steel than for 1043 steel (203HV0,2). At 20°C, ductility only differed by 3% for the both heats. Decrease of tensile properties occurred at higher temperatures of 600 up to 1100°C. This tensile properties decrease at high temperatures is evident for most of metals. The strength level difference of the both heats in the temperature range 20°C up to 1100°C corresponded to 83 MPa, while between 600°C and 1100°C the difference was only 18 MPa. In the temperature range 600°C to 800°C, a decrease in ductility values down to 14 % (1045 heat), or 22 % (1043 heat), was noticed. This decrease was accompanied with occurrence of complex Aluminium oxides in a superposition with detected AlN particles. Further ductility decrease was only noted for 1043 heat where higher occurrence of shrinkag porosity was observed which might have contributed to a slight decrease in reduction of area values in the temperature range 900°C to 1100°C, in contrast to 1045 heat matrix.
The results of the modification of austenitic matrix in cast high-manganese steel containing 11÷19% Mn with additions of Cr, Ni and Ti were discussed. The introduction of carbide-forming alloying elements to this cast steel leads to the formation in matrix of stable complex carbide phases, which effectively increase the abrasive wear resistance in a mixture of SiC and water. The starting material used in tests was a cast Hadfield steel containing 11% Mn and 1.34% C. The results presented in the article show significant improvement in abrasive wear resistance and hardness owing to the structure modification with additions of Cr and Ti.