Volume 14 (2014): Issue 1 (March 2014)

The multi-objective optimization procedure of geometry of TiAlN/TiN/Cr multilayer coatings was created. The procedure was applied to the multilayer coatings subjected to constant tangential and normal loads (Hertzian contact). In physical model Cr, TiN and TiAlN layers were treated as a continuous medium, thus in mathematical description of the stress and strain states in the coatings a classical theory of stiffness was used. Decisional variables used in procedure were thicknesses of Cr, TiN and TiAlN layers and decisional criteria were functions of the stress and strain fields in the coating and substrate. Using created optimization procedure, Pareto set of optimal values of layers' thicknesses were determined. Additionally, two methods of analysis of Pareto-optimal set were introduced and discussed.

The tests results of superduplex stainless steel welded joints made with a different heat input, using automatic submerged arc welding (SAW) and semi-automatic flux-cored arc welding (FCAW) have been presented. Metallographic examinations, the measurements of the ferrite content, the width of the heat affected zone (HAZ) and the hardness of the welds in characteristic areas have been performed. Significant differences in the amount of ferrite in the weld metal and in the heat affected zone microstructure of joints were found.

The paper presents the study results on chemical composition of the coarse primary M7C3 carbides occurring in the soft annealed NC11LV/D2 tool steel consisting of: 1.53% C; 11.65% Cr; 0.01% W; 0.81% Mo; 0.068% V; (balance iron plus admixtures), used for cold operation. The microanalyzer of type SEMPROBE Su-30, French made by CAMECA Co., equipped with two WDS X-ray spectrometers and an EDS VOYAGER 3 100, NORAN Instruments Co., made in USA. It was found that out of the three alloying elements occurring in the big carbides of the annealed NC11LV/D2 steel, i.e. Cr, Mo, and V, the chromium appears to be the most uniformly distributed. The big carbides vary concerning C, Cr, Mo, V; the greatest differentiation degree of the contents of Mo and Cr, and the least - of vanadium. The average chemical composition of the big/coarse carbides is as follows: C = 9.42±1.28%; Cr = 44.17±2.95%; Mo = 4.48±3.52%; V = 4.53±0.31%; balance Fe.

In the paper, there are presented the analyses of iron Fe2p3/2 and chromium Cr2p3/2 and oxide O1s XPS spectra of surfaces obtained after abrasive and electrochemical polishing with additional treatment as chemical chelating in the solution containing of 10% Citric Acid and 2% Ethylenediaminetetraacetic Acid. There was also performed electro-chelating after mechanical polishing in the electrolyte for chemical chelating. The maximum values of chromium compounds to iron compounds ratio were obtained after electropolishing with and without stirring with chemical chelating in Citric Acid and EDTA and they were in rage from 3.5 to 3.6. The minimum value was obtained for the steel surface after abrasive polishing and electro-chelating and was equal 1.3. After electrochemical polishing and chemical passivation in the surface layer there were detected FeO and Cr(OH)3 as dominated compounds. After abrasive polishing and electro-chelating there were mostly Fe2O3 and Cr2O3.