Materials used in abrasive wear conditions are usually selected according to their microstructure and hardness, however, other factors such as grain size, matrix saturation, carbides size and morphology are rarely considered. Therefore, the present study deals with the influence of different heat and chemical-heat treatments including their combination on abrasive wear resistance of X210Cr12 tool steel. The effects of material hardness, carbide morphology and microstructure on wear resistance after quenching and nitriding were also investigated. One sample series was quenched after austenitization at 960 • C for 20 min and tempered at 180 • C for 2 h. The second sample series was quenched from 1060 • C austenitization for 20 min and afterwards twice tempered at 530 • C for 1 h. From both the quenched and tempered states, one half of the samples was gas nitrided in NH 3 atmosphere for 3 h and then diffusion annealed in N 2 atmosphere for 4 h. Abrasion wear tests were performed by sliding the samples on Al 2 O 3 paper. The samples weight loss was considered the main criterion for the wear resistance evaluation. The microstructures, nitrided layers and worn surfaces were observed using SEM microscopy. The highest abrasion wear resistance was obtained for the nitrided samples that were previously quenched from 1060 • C and tempered at 530 • C.
The effect of severe plastic deformation by ECAP process on the microstructures and mechanical properties of the aluminium alloy EN AW 6082 produced by cold extrusion is investigated. In both states were evaluated the structural changes by light microscopy, the analysis particles in structures, by X-ray diffraction (XRD) in transmission mode by synchrotron radiation and mechanical properties. Severe plastic deformation leads to strengthening of investigated EN AW 6082 alloy but on the other hand the plasticity of ECAP-ed alloy decreases.
The paper analyses the influence of the strain rate on the behaviour of unalloyed steels with Re 210 – 550 MPa in the deformation process. It presents and analyses the results of the influence of the strain rate ranging from 10-3 to 2.5.102 s-1 on the yield point, the tensile strength, the elongation and the reduction of area. It analyses the non-homogeneity of development of plastic deformation from both the macroscopic and microscopic points of view, as well as the influence of the strain rate on the development of plastic deformation. Since the intensity of the influence of the strain rate on the properties of materials depends on their internal structure, the tested steels are divided into three groups based on their yield point and yield point to tensile strength ratio.
The main aim of this work is to point out on possibility of properties improving of the aluminium alloy EN AW 6082 (AlSi1MgMn) with an appropriate combination of pre-ECAP solution annealing, the application of the severe plastic deformation by ECAP technology (equal channel angular pressing) and post-ECAP artificial aging. The effect of the severe plastic deformation and artificial aging on the alloy structure was evaluated by metallographic analysis, and alloy mechanical properties by uniaxial tensile test at room temperature, the Vickers hardness and by tribology test of resistance to abrasive wear. As a result of strain hardening by severe plastic deformation it reaches the improvement in hardness (by 56%), strength characteristics (yield strength by 92%, tensile strength by 29%) and abrasion wear resistance is 28 %. Keywords: severe plastic deformation, tension test, aluminium alloys, wear IntroductionThe aluminium alloys belonging to 6XXX groups, which are widely used in structural applications, the construction industry, the automotive industry and architectural section as extrusions products [1]. AlSi1MgMn alloy is characterized by good mechanical properties, resistance to tribology (abrasion wear) and corrosion degradation, low density. Due to good tribological properties of alloy can be used in excellent application. These properties can be increased by strengthening mechanisms: alloying additives respectively heat treatment and the severe plastic deformation [2][3]. The AlSi1MgMn alloy is alloyed from the main elements namely magnesium and silicon. At higher magnesium content tends to increase strength properties of hardened alloy formation of Mg 2 Si phase. Silicon improves mechanical properties by changing the shape of the grain. Except of the main alloying elements, there are added the alloy chromium and manganese which form dispersion particles. These are larger than the other precipitates that can act as nucleation sites for strengthening precipitations, and have good thermal stability, which influences the recovery and recrystallization [4][5][6] Another way of improving the properties of the alloy is heat treatment (consisting of solution treatment, quenching in water, and a natural or artificial ageing treatment). From the
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