The mechanical properties of OFHC copper and CuCrZr alloys after asymmetric rolling at ambient and cryogenic temperatures

Abstract

This work deals with comparing the mechanical properties of OFHC copper and CuCrZr alloys processed by asymmetric ambient rolling (ASaR) and asymmetric cryorolling (AScR). The conditions for asymmetrical rolling were ensured by different diameters of the main rolls. The thickness of samples was reduced about 20% - 70% at ambient temperature and at a temperature of liquid nitrogen. Mechanical properties such as yield strength, tensile strength, reduction of area and microhardness were determined for all rolled samples. Rolling at cryogenic temperatures provide about 50-60MPa more tensile strength for Cu and 60-80 MPa for CuCrZr alloys when rolling at ambient temperature. After AScR of CuCrZr alloys, a start of precipitation was shifted at the temperature of 434∘C and recrystallization was a part of the precipitation peak. According to the results, plastic deformation through shear bands is the dominant mechanism in materials with lower stacking fault energy (CuCrZr) treated under cryogenic conditions.

The effect of neutron irradiation on mechanical properties of CuCrZr alloys processed by cryorolling

“…The higher UTS and YS is caused by the suppression of dynamic recovery during deformation under cryogenic condition and the activation of twinning. The latter is observed in the microstructure inside the shear bands in a form of nanotwins, as it was reported in [12,13]. After irradiation, both AScR and AScR + HT are deformed uniformly up to 0,5%, while ductility is 6% and 5,5 %, respectively.…”

“…After experimental rolling, the precipitation heat treatment was carried out at 430 °C for 30 min followed by air cooling. The artificial aging temperature of this UFG microstructure was determined based on the results of our previous research [13].…”

“…This can be achieved using the severe plastic deformation (SPD), which is a very effective method of production of bulk ultrafinegrained (UFG) and nanostructured materials with novel characteristics [2,7]. The mechanical properties and microstructure of CuCrZr alloy can be modified by several SPD methods, such as high-pressure torsion (HPT), multi-directional forging (MDF), equal-channel angular pressing (ECAP) and asymmetric rolling (ASR), in some cases also at cryogenic temperatures [7,[10][11][12][13]. The increased ductility was observed in Cu-10%Al with UFG structure compared to the conventional coarse-grained alloy [14].…”

On some Features of the Grain and Subgrain Size in a Cu-Cr-Zr Alloy After ECAP Processing and Aging

“…The cells become subgrains. with the addition of Cr and zr, the sFe of Cu-Cr-zr alloy becomes lower than that of pure Cu [41]. The sFe of pure copper is 78 mJ/m 2 [42].…”