Oxidation state of individual alloying elements (Si, Al) and impurity element (Cu) upon segregation onto the surface of the sample FeSiAl alloys was investigated in an in situ study of segregation behavior in ultra-high vacuum. Chemical state of surface Si, Al and O as well as Cu was evaluated, by measuring the kinetic energy shifts that affect Si KLL, Al KLL, O KLL but also Cu LMM transitions, depending on chemical state of the element. It was found that Al oxidizes with temperature in all samples while Si behaves differently with maximum oxidation occurring around 300 °C, and oxidation not occurring at all in some samples. Segregated Cu stays predominantly in its elemental state which is consistent with relevant literature reports.
COBISS.SI-ID: 13283355
This paper presents a comparison in behaviour of two Zn coated, low carbon steels during deep drawing of bearing housing. The failures occurred during deep drawing process only for one steel. The experimental work consisted of a visual inspection, microscopic examination and chemical analysis of both materials. Metallurgical tests revealed the difference in microstructure and in carbon content. The anisotropy in behaviour was observed during deep drawing process. Metallography confirmed formation of longitudinal micro and macrocracks and elongated chains of cementite particles in matrix of ferrite. This study highlights the detrimental effect of the interface cementite particle/ferrite matrix as the main reason for the microcracks formation and reduction of steel capacity for deep drawing.
COBISS.SI-ID: 1053354
Over the last decades considerable efforts are made to develop high performance spring steels, which would allow vehicles weight reduction. One way of improving steel properties is by refining its microstructure and reducing amount of inclusions. In the presented work the effect of cleaner and more uniform microstructure obtained through electro-slag remelting (ESR) on the mechanical and dynamic properties of spring steel was investigated. Effect of the microstructure refinement was evaluated in terms of tensile strength, elongation, fracture and impact toughness, and fatigue resistance under bending and tensile loading. Results show that while ESR gives some improvement, especially in terms of better repeatability and reduced scattering, it has negative effect on fatigue properties of the spring steel.
COBISS.SI-ID: 1015210
The development of design guidance for stainless steel structures requires more tests on ferritic grade connections. This paper deals with a series of lap shear tests which have been carried out on various configurations of bolted and screwed connections. The tests demonstrate net section failure, bearing failure and block tearing failure. The material is a ferritic stainless steel of grade 1.4509 (AISI 441) with a thickness of 0.5-4.5 mm. The results are utilized in developing design guidance in accordance with Eurocodes.
COBISS.SI-ID: 1067946
The benefit of the method for reheating for hot working of tool steel, is reduced scale formation and lower decarburization of the surface. The reheating process of tool steel starts in oxidative atmosphere with holding in the region of Ac1, that is at steel W.Nr. 1.3343 at 780 oC and at steel W.Nr. 1.2379 at 815 oC. In this stage of reheating in oxidative atmosphere (with 10 % oxygen) forms low temperature compact scale, that protects the steel surface during later reheating for hot working, at higher temperatures in the atmosphere of 1 to 1,5 % of oxygen. In comparison with classical reheating process, the proposed method reduces the waste of material due oxides formation and reduses decarbusization of the surface, which both improve the quality of steel surface.
COBISS.SI-ID: 975018