Based on the research work done in the field of materials characterization and development of new mwthod for the determination of fracture toughness of brittle metallic materials dr. Podgornik and dr. Leskovšek were invited to act as guest editors for special issue of Materials Performance and Characterization journal devoted to Fracture toughness. In this special issue 30 contributions from the field of fracture toughness modeling, measurement and analysis were edited and published. In this special issue also contribution from dr. Podgornik, describing non-standard circumferentially notched and precracked specimen used for measuring fracture toughness of brittle materials, like tool steels.
C.03 Guest-associated editor
COBISS.SI-ID: 1081002Invited by Prof. R. Veinthal and Prof. P. Kulu from the Tallinn University of Technology, Dr. Podgornik prepared a lecture for postgraduate students of "High-Tech Materials". In his lecture he gave an overview of hard coatings used for tools and machine parts. The review involved methods, tribological and mechanical properties, and degree of industrialization. The second part has covered the limitations, problems and approaches to the proper selection of hard coatings for given application, mainly form the steel substrate properties, preparation and microstructure point of view.
B.05 Guest lecturer at an institute/university
COBISS.SI-ID: 1078442Research in the field of high- and ultra high-strength steels indicates that appropriate modification of spring steel with increased content of Si, Mo, Ni and Cr, and the addition of B and Ti gives the possibility of producing steels with yield strength of over 1600 MPa and decarburization depth below 0.3 mm. It was found that Si and Cr have the biggest influence on mechanical, as well as on dynamic properties of spring steel, with their high content providing sufficient resistance to decarburization, high yield strength and good dynamic properties. Research results led to the development of a new series of high- strength spring steel with a tensile strength of over 2000 MPa, and high level of impact and fracture toughness.
F.06 Development of a new product
COBISS.SI-ID: 1104298Based on the research work and results published in the field of creep and creep resistant steels, Prof.dr. F. Vodopivec and dr. B. Žužek were invited to have invited talk at the annual Materials and Metallurgy conference organized by Croatian Metallurgical Society. In the invited lecture concept of disjunctive matrix stacionary creep was presented and explained. The particles cut the dislocation line in segments and are ovecame by climbing of segments orthogonal to lattice glide plane. In particle conjuctive matrix, the dislocation length decrease with consumption of energy for glide and climb, while, in particle disjunctive matrix, additional greater energy is consumed for lengthening of dislocation segments. Applying the Horbogens creep equation improved with inclusion of the average size and spacing of particles and a constant representing the increase of stress exponent, the difference in experimental and calculated creep rates is lover than 10 %.
B.04 Guest lecture
COBISS.SI-ID: 1066922The research concerning the processing of the steel melt in the primary aggregate revealed that certain chromium losses cannot be avoided, due to thermodynamic conditions. The choice of charging material, temperatures of the process and the degree of oxidation were proven to have the greatest effect on the loss of chromium. Optimization of the addition of reductive agents in the steel making process was done through the mass balance of both the melt and slag on the basis of chemical analysis. Reduction of the slag was worsened when magnesite chromite spinels were present; the degree of chromium reduction was much lower than proposed by theoretical calculations. The results showed that certain chemical composition of oxides in the slag prevent economical use of reductive agents, as their consumption is too high. Based on the results existing process (UHP-VAD) of making stainless steel was optimized and improved.
F.10 Improvements to an existing technological process or technology
COBISS.SI-ID: 1103530