Alloy element

ASTM F-138 standard Range (%wt)

Uncorroded screw (%wt)

Corroded screw (%wt)

Cr

Min 17.00; Max 19.00 ± 0.20

14.808

25.779

Ni

Min 13.00; Max 15.00 ± 0.15

9.144

15.496

Mo

Min 2.25; Max 3.00 ± 0.10

1.765

3.154

Mn

Max 2.00 ± 0.04

0.979

1.922

Co

-

0.188

0.276

Cu

Max 0.50 ± 0.03

0.240

0.738

Ti

-

0.006

0.009

C

Max 0.030 ± 0.005

Si

Max 0.75 ± 0.05

N

Max 0.10 ± 0.01

P

Max 0.025 ± 0.005

S

Max 0.010 ± 0.005

PRE = %Cr + 3.3 * % Mo

PRE ≥ 26

20.632

36.187