Die angle for Duplex stainless steel wire

Hi,
Please guide/help!
I have read the Drawing die chapter 14 from `Ferrous Wire Handbook´, and found out that it is recommended to use wider angle die ,around 18 degree approach angle for stainless steel.
It is not elaborated in good detail in the text book and I am confused for whether to use this 18 deg angle for the entire die pass schedule( decreasing reduction sequence) or mix the die angles( 18 deg for 1st red and 12 deg for later small reductions).

After a quick look, it appears to imply that the 18 degrees would apply to all dies in the set.However, I would suggest that you calculate the delta parameter for 18 degrees with a "normal" reduction and then keep delta in this range by calculating the angle needed for the reduced reductions.
Hope this helps.