New Approach In The Properties Evaluation Of Ultrafine-Grained OFHC Copper

Abstract

In this study, static, dynamic and tribological properties of ultrafine-grained (UFG) oxygen-free high thermal conductivity (OFHC) copper were investigated in detail. In order to evaluate the mechanical behaviour at different strain rates, OFHC copper was tested using two devices resulting in static and dynamic regimes. Moreover, the copper was subjected to two different processing methods, which made possible to study the influence of structure. The study of strain rate and microstructure was focused on progress in the mechanical properties after tensile tests. It was found that the strain rate is an important parameter affecting mechanical properties of copper. The ultimate tensile strength increased with the strain rate increasing and this effect was more visible at high strain rates (ε ∼10 2 s −1 ). However, the reduction of area had a different progress depending on microstructural features of materials (coarse-grained vs. ultrafine-grained structure) and introduced strain rate conditions during plastic deformation (static vs. dynamic regime). The wear behaviour of copper was investigated through pin-on-disk tests. The wear tracks examination showed that the delamination and the mild oxidational wears are the main wear mechanisms.Keywords: OFHC copper, UFG, ECAP, strain rate, fractography, wear resistance W pracy zbadano szczegółowo statyczne, dynamiczne i tribologiczne właściwości ultra drobnoziarnistej (UFG) beztlenowej miedzi o wysokiej przewodności cieplnej (OFHC). W celu oceny właściwości mechanicznych przy różnych szybkościach odkształcenia, miedź OFHC badano za pomocą dwóch urządzeń w warunkach statycznych i dynamicznych. Ponadto miedź poddano dwóm różnym sposobom przetwarzania, co umożliwiło badanie wpływu struktury. Badanie szybkości odkształcenia i mikrostruktury koncentrowało się na zmianie właściwości mechanicznych po próbie rozciągania. Stwierdzono, że szybkość odkształcania jest ważnym parametrem wpływającym na właściwości mechaniczne miedzi. Wytrzymałość na rozciąganie wzrosła ze wzrostem szybkości odkształcenia i ten efekt był bardziej widocznyprzy dużej szybkości odkształcania (ε ∼10 2 s −1 ). Jednak zmniejszenie obrazu przebiegało inaczej w zależności od cech mikrostruktury materiałów (struktura gruboziarnista a struktura ultra drobnoziarnista) i zadanych warunków szybkości odkształcenia podczas odkształcenia plastycznego (warunki statyczne a warunki dynamiczne). Zużycie miedzi badano za pomocą testów zarysowania. Badanie ścieżek zużycia wykazało, że delaminacja i umiarkowane utlenienie to główne mechanizmy zużycia.

Indentation Size Effect of Heat Treated Aluminum Alloy

“…The YS/UTS ratio, which controls the local loss of plastic stability due to the internal structure of material (nonhomogeneity, defects, but also due to the processing technology) for example in the deep-drawing process. High value of the ratio results in restricted formability and resistance to fatigue fracture on the other hand [8,9]. As the temperature of the solution treatment rises, the YS/UTS ratio and also Meyer's index n increase.…”

SYNTHESIS OF Cu2ZnSnS4 BY MECHANICAL ALLOYING METHOD FOR THERMOELECTRIC APPLICATION

“…The formation mechanism of CZTS during high-energy ball mill is attributed tothe diffusion process, which takes place when particles are cold-welded together. Heavy plastic deformations during milling createa variety of crystal defects such asdislocations, vacancies, stacking faults, and increasethe grain boundaries, and so, enhances the diffusion process.In addition, slightly temperature raise during milling further aids the diffusion process; consequently, true compound is formed.The specific times required to develop a given structure in any system depends on the initial particle size, characteristics of the ingredients,and the operating parameters of the equipment [21][22][23].…”

Investigation of the Ultrafine-Grained Structure Formation under Different Strain Rates

“…Fig. 2 is an example displaying load and time progress during measuring in dynamic conditions [38]. The load and time progress indicates occurrence of the wave in the sample during measuring.…”

“…2. The load-time dependence for the drawing state (3 m/s) [38] Fig . 3 illustrates progress of mechanical properties on strain rate for samples after drawing and ECAP processing (CG vs. UFG) in the dynamic regime.…”