Microstructure and Phase Effects on EAF - Electrically Assisted Forming - page 183

Table 8.4 Summary of %CW and annealed stationary electrical test results [ 5 ]
Stat. elec. test description Maximum

temp. (°C)

Thermal profile description

10 %CW (CD = 10), 2,225 N 200 Thermal profiles are almost flat, signifying that

thermal saturation was almost reached

10 %Ann (CD = 10), 2,225 N

160

425 Thermal profiles very curved, signifying that

the specimens did not reach thermal saturation

10 %CW (CD = 20), 2,225 N

10 %Ann (CD = 20), 2,225 N 330

230 Curved thermal profiles with a constant

temperature difference over the test duration

20 %CW (CD = 10), 2,225 N

200

20 %Ann (CD = 10), 2,225 N

30 %CW (CD = 10), 2,225 N 300 Linear-type thermal curvature with

a constant 100 °C difference over the test

200

30 %Ann (CD = 10), 2,225 N

365 Temperature difference increased

from 75 to 165 °C

40 %CW (CD = 10), 2,225 N

40 %Ann (CD = 10), 2,225 N 200

110 Linear-shaped thermal profiles with

increasing temperature difference to 25 °C

30 %CW (CD = 10), 42,275 N

85

30 %Ann (CD = 10), 42,275 N

40 %CW (CD = 10), 50,063 N 117 Linear-shaped thermal profile with

a small temperature difference (20 to 35 °C)

82

40 %Ann (CD = 10), 50,063 N

120 Linear-shaped thermal profile with

a small temperature difference (25 to 40 °C)

50 %CW (CD = 10), 62,300 N

50 %Ann (CD = 10), 62,300 N 80

Table 8.4 summarizes the findings from the thermal results of the station-
ary electrical tests. For the same respective current density (10 A/mm 2 ), the tem-
perature increased as the %CW increased (to an overall temperature difference of
165 °C). For the annealed specimens, there was only a 40 °C difference in the 10 %
annealed specimen temperature compared to the 40 % annealed thermal profile.
From the data in Table 8.4 and Fig. 8.8 could be created which shows the rela-
tionship between the maximum temperature of the stationary electrical tests and
the initial percent cold work. In this figure, the maximum temperature (which con-
sistently occurred at the end of the tests) increased as the initial percent cold work

Fig. 8.8 Temperature
versus percent cold work
relationship for SS304
[ 5 ]. The temperatures of
stationary electrical tests
at the same current density
increased as the initial
percent cold work was
increased

400

Temp. (%CW) = 0.0875(%CW) 2 + 1.275(%CW) + 176.25

350

300

Worked
Annealed
Poly. (Worked)

250

200

150

100

0 10 20 30 40 50

Percent Cold Work (%CW)