“THE IMPORTANCE OF IRON IN
90/10 COPPER-NICKEL”
Copyright © 2013 GBC Metals, LLC. All rights reserved.
THE HISTORY OF IRON IN
90/10 COPPER-NICKEL
• 1949 – 1% max iron specified by ASTM B111
(thus 90/10 with no iron met spec.)
• 1952 – “Corrosion-Resisting Characteristics of
Iron-Modified 90:10 Cupro Nickel Alloy”
presented at 8th annual NACE conference
• 1952 – Iron specification was changed to 0.5-2.0%
• 1960’s – Iron specification changed to current 1.0-1.8%
THE EFFECT OF IRON ON
THE GENERAL CORROSION RESISTANCE
OF 90/10 COPPER-NICKEL
10
9
Corrosion Rate, mdd
8
7
6
5
4
3
2
1
0
0
0.5
1
1.5
2
Percent Iron
2.5
3
3.5
4
Erosion-Corrosion Rates and Magnetic Permeability Data
for 90/10 Copper-Nickel at Two Flow Rates in Seawater **
Percent Iron in
90/10 Cu-Ni
0.01
0.48
0.71
0.95
1.19
1.44
1.96
Erosion-Corrosion Rate, mdd
Velocity = 30 ft/s
Velocity = 15 ft/s
Cond. A Cond. B Cond. C Cond. A Cond. B Cond. C Cond. A Cond. B Cond. C
1.00
1.00
1.00
138
138
137
106
105
104
1.00
1.00
1.00
119
115
124
71
72
85
1.00
1.00
1.18
121
118
110
64
75
49
1.00
1.04
1.14
96
93
104
27
63
47
1.00
1.27
1.55
87
98
87
26
65
39
1.00
1.28
1.83
36
84
99
17
58
49
1.00
1.44
2.40
26
79
84
10
55
51
Magnetic Permeability, µ
0
Condition A - Quenched from 900 C. Iron in solution.
0
0
Condition B - Quenched from 900 C; reheated 2 hours at 550 C, except for alloys containing 1.00% or
0
more iron, which were reheated 2 hours at 600 C. Partial precipitation of iron-rich phase.
0
0
Condition C - Quenched from 900 C; reheated 8 hours at 650 C. Maximum precipitation of iron-rich phase.
** Corrosion Resisting Characteristics of Iron Modified
90-10 Cupro-Nickel Alloy – Stewart & LaQue
STRAND ANNEALING AT OLIN BRASS
PUTS IRON INTO SOLUTION
Continuous strand annealing, versus
batch annealing, is utilized and results in
a more uniform temper from one tube to
another; this is beneficial for the rolling
of tubes into tubesheets. The Strand
Annealing furnaces include a water
quench at the exit end of the furnaces.
90/10 copper-nickel includes 1.0-1.8%
iron, and the resistance of 90/10 coppernickel to erosion-corrosion and stress
corrosion is optimized when the iron is
present in solid solution; our high
temperature strand anneal followed by a
water quench puts the iron in solid
solution.
THE EFFECT OF SOLUTIONIZED IRON ON
THE EROSION-CORROSION RESISTANCE OF
90/10 COPPER-NICKEL **
Seamless 90/10
Fineweld Tube
“As-Welded” 90/10
15 fps Flow Rate
** Corrosion Resisting Characteristics of Iron Modified
90-10 Cupro-Nickel Alloy – Stewart & LaQue
THE IMPORTANCE OF MAGNETIC
PERMEABILITY AS A SPECIFICATION FOR
90/10 COPPER-NICKEL
70
60
Erosion-Corrosion Rate, mdd
A restrictive iron
content of 1.2-1.8%
AND a magnetic
permeability of 1.05
mu maximum
optimizes the
erosion-corrosion
resistance of 90-10
copper-nickel
50
40
.95% Fe
30
1.19% Fe
20
1.44% Fe
1. 05 µ max.
10
0
0.90
1.10
1.30
1.96% Fe
1.50
1.70
1.90
Magnetic Permeability, µ
2.10
2.30
2.50
THE EFFECT OF SOLUTIONIZED IRON ON
THE STRESS CORROSION RESISTANCE OF
90/10 COPPER-NICKEL **
STRESS CORROSION TEST RESULTS
IN MOIST AMMONIA (pH =10.3)
90/10 with No Iron – Cracks @ 36 h
90/10 with 1.5% Iron (Precipitated Iron) – Cracks @ 110 h
90/10 with 1.5% Iron (Solutionized Iron) – No Cracks @ 1000 h
** The Effects of Iron on the Stress Corrosion Resistance of 90/10
Cupro-Nickel in Ammoniacal Environments - Popplewell
HOW TO OPTIMIZE THE EROSIONCORROSION AND STRESS CORROSION
RESISTANCE OF 90/10 COPPER-NICKEL
Specify a Restricted Iron Content of
1.2-1.8% Iron.
Specify a Magnetic Permeability of
1.05µ maximum.