No abstract

The present study reveals for the first time the dry sliding wear behavior of a powder metallurgical pure titanium alloy (Cp-Ti) modified by shot peening. Cp-Ti samples were manufactured via powder metallurgy, and then their surface and subsurface features were modified using a custom-made, fully automated shot-peening system. The texture isotropy rate and the highest orientation angle of the shot-peened samples were 71.5% and 36°, respectively. The Abbott curves of the shot-peened surfaces revealed that the most common areal roughness value was 5.177 μm, with a frequency of 8.1%. Shot-peened surfaces exhibited an ~20% lower wear rate than unpeened surfaces under dry sliding wear, whereas the coefficient of friction was the same for both surfaces. Micro-ploughing, micro-cutting, oxidation, and three-body abrasion wear mechanisms were observed on the shot-peened and unpeened surfaces. High resolution 3D surface topographies of worn unpeened and shot-peened surfaces revealed micro-scratches and inhomogeneities along wear tracks, which are indicative of three-body abrasion mechanisms during contact. In addition, vertical and horizontal microcracks were visible just beneath the wear track, suggesting a clear indication of plastic deformation during contact. The cross-sectional hardness maps of shot-peened samples revealed the formation of a work-hardened surface layer with shot peening, which improved the wear resistance. These findings support that shot peening can be a useful tool to modify the surface and tribological properties of powder metallurgical Cp-Ti alloys.

Abstract.Weld overlay coatings also known as hardfacing is a method which involves melting of the alloys and solidification for applied coatings. Recently hardfacing by welding has become a commonly used technique for improvement of material performance in extreme (high temperature, impact/abrasion, erosion, etc.) conditions.In the present study, the coatings were produced from a mixture of ferrous niobium, ferrous boron and iron powders in the ranges of -45 μm particle size with different ratio.

Recently hardfacing by welding has become a commonly used technique for improvement of material performance in extreme (high temperature, impact/abrasion, erosion, etc.) conditions. In the present study, three di erent alloy compositions of the Fe Nb B were used for hardfacing of the AISI 1020 steel by tungsten inert gas welding process and analyzed. The coatings were produced from a mixture of ferrous niobium, ferrous boron and iron powders in the range of −45 µm particle size with di erent ratio. The coatings' thickness was set to 2 3 mm on the substrate. Microstructure, phase analysis and hardness of the manufactured hardfacing alloys were characterized. Deposition results indicate good quality thick coating and porosity free of the hardfacings. X-ray di raction analyses showed that the alloyed layers include iron borides, FeNbB and iron phases. It was shown that surface alloyed layer has composite structure including steel matrix and well distributed boride phases.

No abstract