This paper deals with the selection of the optimal material for railway wagons, from among three different steel and three aluminium based materials, by using four different Multicriteria Decision Making Methods (MCDM) and comparing their ranking of the materials. We analysed: Dual-Phase 600 steel, Transformation-Induced Plasticity (TRIP) 700 steel, Twinning-Induced Plasticity (TWIP) steel, Aluminium (Al) alloys, Al 6005-T6, and Al 6082-T6, and porous Al structure with closed cells. Four different MCDM methods were used: VIKOR, TOPSIS, PROMETTHEE and the Weighted aggregated sum product assessment method (WASPAS). Key material properties that were used in the MCDM analysis were: density, yield strength (Y.S.), tensile strength (T.S.), Y.S./T.S. ratio, Youngs modulus (Y.M.), cost and corrosion resistance (C.R.). Research results indicate that aluminium and its alloys prove to be the most suitable material, based on setup criteria. Advanced steels also achieved good ranking, making them a valid option, immediately behind lightweight aluminium alloys. Porous aluminium did not perform well, according to the used MDCM methods, mainly due to the significantly lower strength exhibited by the porous structures in general.

Mechanical surface preparation is a common technique for removing contaminants from surface metal layers. Unlike chemical preparation, it does not require special safety measures, including those for disposal of by-products or toxic materials, thus making it more accessible for different industries. We investigated tribological testing as the experimental method to determine the quality of the coating and the influence of the initial mechanical surface treatment. Samples were made of aluminium alloy EN AW 5083 H111 that was shot blasted with white cast aluminium with resulting surface roughness of Rz=38.908 μm. Samples were further coated with Lankwitzer EvoCor 164 2-component epoxy primer. Tribological test realised on nanotribometer is described and output parameters have been analysed: friction coefficient and penetration depth. Ball-on-flat, dry contact tribological setup was used, with 100 mN normal load, under linear reciprocating motion. Dynamic friction coefficient and penetration depth curves during one tribological test were analysed indicating the moment when the coating exhibited first failure. The test has shown that tribological tests with low loads can be used for quality testing of thin coatings, including the influence of the mechanical surface preparation on the coating adhesion.