Instructions / Assembly

45
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Predictions by the WRC-1992 and WRC-DeLong diagrams for
common grades like 308 are similar, but the WRC-1992
diagram generally is more accurate for higher alloy and less
common grades like high manganese austenitic or duplex
ferritic-austenitic stainless steels.
Ferrite Number can be measured directly on weld deposits from
the magnetic properties of the ferrite. Several instruments are
available commercially, including the Magnet Gage, the Severn
Gage, the Inspector Gage and the Ferritescope which can be
calibrated to AWS A4.2 or ISO 8249 and provide readings in
Ferrite Number.
The amount of ferrite normally should not be greater than neces-
sary to prevent hot cracking with some margin of safety. The
presence of ferrite can reduce corrosion resistance in certain
media and excess ferrite can impair ductility and toughness.
18
18 20 22 24 26 28 30
18 20 22 24 26 28 30
16
14
12
10
18
16
14
12
10
A
F
AF
FA
0
2
6
4
8
10
12
14
16
18
20
22
24
26
28
30
35
40
45
50
55
60
65
70
75
80
85
90
95
100
Cr
eq
= Cr + Mo + 0.7Cb
Ni
eq
= Ni + 35C + 20N + 0.25Cu
Cr
eq
= Cr + Mo + 0.7Cb
Ni
eq
= Ni + 35C + 20N + 0.25Cu
F
IGURE 33 — New 1992 WRC diagram including solidification mode boundaries.
Updated from T.A. Siewert, C.N. McCowan and D.L. Olson – Welding Journal,
December 1988 by D.J. Kotecki and T.A. Siewert - Welding Journal, May 1992.