Final Report - Strategic Environmental Research and Development ...

The DOE coupons were prepared at both EWI and ASAP. This allowed for comparison
of the effect of applying ESD at different sites. It was assumed that there would be no
effect.
The DOE was executed on flat coupons, containing Type 1 defects as shown in Figure
4-4. Each defect was filled, based on the settings described for each trial. If the defect
did not fill after four hours, the process was stopped. All ESD was performed at room
temperature with argon cover gas. IN718 parameters used (DOE inputs) are summarized
in Table 4-6 and Table 4-7.
Table 4-6 IN718 DOE Inputs - Multiple Levels
Multiple Levels
Parameter
Range
Pulse Rate 300 – 500 Hz, increments of 100
Voltage 80 -130 V, increments of 25
Capacitance 30 – 50 µF, increments of 10
Electrode Revolution speed 800 – 1600 rpm, increments of 400
Electrode Size 0.125 - 0.09375 inch (1/8, 1/16, 3/32)
Table 4-7 IN718 DOE Study - Fixed Levels
Parameter
Shielding Gas
Cleaning Frequency
ESD Surface reshaping (i.e. filing)
Operating Environment
Fixed Value
Argon
As needed
As needed
Room temperature
4.2.3. DOE Outputs
The DOE was evaluated using measured outputs. The recorded outputs were deposition
rate, microhardness and deposit discontinuities. Other outputs that were noted included
current, surface finish, microstructure, and the results of non-destructive evaluation
(NDE).
The outputs were recorded in a spreadsheet and/or on forms designed by Edison Welding
Institute. One, the Welding Procedure Specification (WPS) (Figure 4-7 in Section 4.1),
was used to record inputs which would not vary, such as the shielding gas composition
and flow rate. The other, the ESD Trailer Data Sheet shown in Figure 4-9, used to record
varied inputs, such as capacitance and voltage, as well as measured outputs such as the
initial and final weights of the coupons (Figure 4-9).
71