Effect of low temperatures on the mechanical properties of Cu-ETP

Remarks: As can be seen from the table, ETP copper (FCC metal) preserve ductility at low temperatures.

Influence of temperature on the mechanical properties of annealed (600°C), forged ETP copper

Mechanical properties of ETP copper as a function of temperature (-180°C to +600°C)

Influence of impurity content on tensile properties of ETP copper annealed at 700°C, 30min.

Remarks: A stronger change in tensile strength and elongation was observed only for Fe addition with a content of more than one percent. For all impurities, with the exception of those mentioned above (>1%), tensile strength was 220 to 262 MPa and elongation was about 45 to 67%, which indicated good ductility properties.

Dependence of tensile strength of ETP copper on its homologous temperature T_h

Mechanical properties vs temperature of Cu-ETP wire rod (diameter 8.0mm) after 1 hour annealing process (At temperatures from 100 °C to 400 °C the UTS of Cu-ETP wire rod is stable, while in the temperature range of 500 °C to 900 decreases)

Elongation A₂₅₀ vs temperature of Cu-ETP wire rod (diameter 8.0mm) after 1 hour annealing process

Variation of tensile properties and grain size of electrolytic tough pitch copper (Cu-ETP) and similar coppers (Cu-ETP1)

Short-time elevated-temperature tensile properties of Cu-ETP (C11000) and similar coppers (Cu-ETP1)

Low-temperature tensile properties of Cu-ETP (C11000) and similar coppers (Cu-ETP1)

Remark: For ETP copper, as for pure aluminium (both FCC metals), the difference between the R_m and R_e magnitudes is larger at low temperature than at room temperature, unlike the BCC metals Cr, Ta and V.

Effect of temperature on the tensile strength R_m and yield limit R_e of Cu-ETP

Tension stress characteristic of Cu-ETP wires (diameter 0.5-8.0 mm) obtained from wire rod after annealing process

Tensile stress characteristic of Cu-ETP wires (diameter 0.5-8.0 mm) obtained from wire rod after annealing process

Elongation vs strain of Cu-ETP wires (diameter 0.5-8.0 mm) obtained from wire rod after annealing process

Remarks: The diagrams lack a physical yield point.

Compression diagrams at 20°C and -180°C of Cu-ETP ductile at low temperatures

Effect of elevated temperatures on the Knoop hardness HK of ETP copper

Softening resistance of Cu-ETP

Microhardness dependence on the annealing temperature for ETP copper samples subjected to ECAP with and without back pressure (BP)

Dependence of the Knoop hardness HK at 0°K (-273,15°C) on the total molar heat capacity W₀ for ETP copper

Thermal expansion and enthalpy of Cu-ETP. (a) Total thermal expansion from -190 °C. (b) Enthalpy (heat content) above 0 °C

Thermal conductivity of Cu-ETP in different temperature

Effect of temperature on the thermal conductivity of ETP copper

Thermal conductivity measurements derived from the thermal diffusivity data for ETP copper

Differential Scanning Calorimetry (DSC) of ETP copper (Differential scanning calorimetry DSC measurements were carried out in order to find out the reason for the change in the TC slope at 200 °C – Fig. above)

Thermal conductivity of ETP copper vs temperature (temperature range -200 to +25°C and range +50 to +600 °C). Measurements were performed by two methods. First method was based on the axial stationary heat flow in the temperature interval -200 to +25°C, namely from thetemperature of liquid nitrogen to room temperature. Second applied method of measurements in the temperature range +50 to +600 °C, was based on indirect measurements at 50, 100, 200, 400 and 600°C, where thermal diffusivity on the nonlinear mathematical Cape-Lehman model was calculated, taking into account radiation losses, an atmosphere of protective gas-argon and the covering of samples with graphite on both sides

Comparison between the nominal thermal conductivity curve for ETP copper RRR 50 (solid line) and the control sample. In theinset four different runs are displayed, showing the reproducibility of our measurements and allowing a better determination of the peak temperature

Thermal conductivity of the ETP copper. The three lines display the thermal conductivity of copper for diferent levels of RRR in order to evaluate those of the copper within the samples

Effect of temperature on the electrical resistivity of ETP copper

Electrical resistivity of ETP copper at subsero temperatures

Softening resistance of cold drawn Cu-ETP wires

Softening resistance of cold drawn Cu-OFE wires 

Effect of the content of different elements added to ETP copper on its recrystallization temperature

Remarks: The effect of foreign atoms on the recrystallization temperature is strongly connected with the type of foreign atoms. Inclusion of foreign atoms mostly increases the recrystallization temperature. In some rare cases (Al, Fe and Bi) impurities decrease the recrystallization temperature. The largest increase of this temperature was for 0,24% Sn (Δt=170°C).

Increase in the recrystallization temperature of ETP copper (205°C) by the addition of 0,01 atomic percent of the indicated element

Remarks: For Te and Se, the increase in the recrystallization temperature is very high.

Influence of temperature on Young’s modulus (E) of annealed ETP copper

Relation between hardness and Young’s modulus of ETP copper at -200°C

Mechanical properties vs temperature of Cu-ETP wire rod (diameter 8.0mm) after 24 hours annealing process

Elongation A₂₅₀ vs temperature of Cu-ETP wire rod (diameter 8.0mm) after 24 hours annealing process

Percentage reduction of area vs temperature of Cu-ETP wire rod (diameter 8.0mm) after 24 hours annealing process

Half-softening temperature of Cu-ETP wire

CuETP (C11000) is subjected to embrittlement when heated to 370 °C or above in a reducing atmosphere, as in annealing, brazing or welding. If hydrogen or carbon monoxide is present in the reducing atmosphere embrittlement can be rapid. Literature:

www.copper.org

ETP copper corrosion in the formic and carboxylic acid

Two experiments were performed in which the relative humidity was kept constant during a major part of the exposure and only the formic acid concentration was varied. Three Cu-500 nm and three Cu-85 nm sensors were exposed to air at 80% and 60% RH, respectively, with increasing acid concentrations. It should be noted that due to the use of different permeation tubes with formic acid, the concentrations were slightly different in the two experiments. An example of the corrosion depth record for a Cu-500 nm sensor is plotted in Fig. below. The other records were similar. The experiment started in clean air at 15% RH. The corrosion rate was below the detection limit until the relative humidity was increased to 70%. The corrosion rate stabilized at about 0.01 nm/day after 4 days and did not change even though the relative humidity was increased to 80% RH. Formic acid did not have a dramatic effect on copper corrosion when present at concentrations from 10 to 220 ppb. When the formic acid concentration was increased to 460 ppb, the corrosion rate changed to 0.05 nm/day. It stayed at this level at 1000 ppb as well. An additional increase in the corrosion rate to 0.14 nm/day was recorded at the maximal formic acid concentration of 1590 ppb. The corrosion rate decreased gradually to low values when the formic acid concentration was lowered to 190, 80 and 0 ppb. Cu-85 nm sensors were used in a similar experiment with a lower maximal relative humidity of 60%. Corrosion rates extracted from stabilized parts of the corrosion depth vs. time records are given in Table below. Analogously to the previous experiment at 80% RH, the corrosion rate of copper only increased above about 0.01 nm/day when the concentration of formic acid was raised from 210 ppb to 420 ppb. Indeed, the increase was stronger under the wetter conditions. Whereas the corrosion rate continued to increase in more contaminated air at 80% RH, it remained nearly constant at 0.04 ± 0.01 nm/day at 60% RH until the formic acid concentration was raised to 2880 ppb .

Corrosion depth measured in air containing formic acid using a Cu-500 nm sensor; numbers give concentration of formic acid in ppb and relative humidity in per cent

Corrosion rate of ETP copper sensors after stabilization in the presence of formic acid

Corrosion rates as a function of the relative humidity and carboxylic acid concentration; (a) copper and formic acid; experimental points:v_corr≤0,015 nm/day,0,015<v_corr≤0,06nm/day,v_corr>0,06 nm/day

 Relaxation at stress level 0.5 × Yield Strength

Stress relaxation curves for Cu-ETP (C11000) and similar coppers (Cu-ETP1). Data are H80 temper wire, 2 mm in diameter, and represent the time-temperature combination necessary to produce a 5% reduction in tensile strength

Creep properties of CuETP, CuETP1 (C11000)

Creep-rupture strength for ETP copper for 100 hours creep

Values given below apply to any of the unalloyed copper in contact with the indicated materials without lubrication of any kind between the contacting surfaces:

Values  shown in table  are typical for all tough pitch, oxygen-free, phosphorus-deoxidized and arsenical coppers. Copper does not exhibit an endurance limit under fatigue loading and, on the average, will fracture in fatigue at the stated number of cycles when subjected to an alternating stress equal to the corresponding fatigue strenght (see Fig.)

Rotating-beam fatigue strength of Cu-ETP (C11000) wire, 2 mm in diameter, H80 temper

The fatigue strength is defined as the maximum bending stress amplitude which a material withstands for 10⁷ load cycles under symmetrical alternate load without breaking. It is dependent on the temper tested and is about 1/3 of the tensile strength .

Influence of impurity content on fatigue limit of ETP copper annealed at 700°C, 30min.

Fatigue factor S/R_m of ETP copper in annealed condition versus the homologous temperature (T/T_mp = ratio of room temperature to melting point, in °K)

Remark: For FCC pure metals there exists a nearly common linear dependence of the fatigue limit on the tensile strength.

Fatigue limit versus tensile strength of recrystallized ETP copper

Remark: The fatigue limit depends on the tensile strength of the metal.

Fatigue limit S_tc of ETP copper versus tensile strength Rm at different temperatures

Fatigue factor S_tc/R_m of ETP copper at low temperatures

Dependence of fatigue limit σ_d and tensile strength R_m on the total heat capacity w_r at room temperature for ETP copper

Summary table of fatigue limits of ETP copper at room temperature

Typical impact strength of Cu-ETP (Cu-ETP1)