alloy 81 NIMONIC - specialmetals.com · NIMONIC ® alloy 81 NIMONIC® alloy 81 is a wrought nickel...
Transcript of alloy 81 NIMONIC - specialmetals.com · NIMONIC ® alloy 81 NIMONIC® alloy 81 is a wrought nickel...
NIM
ONIC
®al
loy
81
wwwwww..ssppeecciiaallmmeettaallss..ccoomm
NIMONIC® alloy 81 is a wrought nickel alloy hardenedby controlled additions of titanium and aluminum, anddesigned to provide enhanced resistance to hightemperature corrosion coupled with good hightemperature strength.
It has excellent hot corrosion resistance due to itshigh chromium content. Elevated temperature strengthcharacteristics are similar to those of NIMONIC alloy80A. Melting, hot-working, cold-working andmachining practices are also broadly similar to those forNIMONIC alloy 80A.
Applications include components for gas turbines,piston engine exhaust valves, and heat-exchange plantsubject to attack by deposits resulting from thecombustion of impure fuels, particularly by alkali metalsulfates and chlorides.
NNoommiinnaall CCoommppoossiittiioonn% max. unless stated
Carbon.................................................................................0.05
Silicon ..................................................................................0.50
Copper.................................................................................0.20
Iron.........................................................................................1.0
Manganese ..........................................................................0.50
Chromium ............................................................................30.0
Titanium.................................................................................1.8
Aluminum...............................................................................0.9
Cobalt ....................................................................................2.0
Molybdenum........................................................................0.30
Boron .................................................................................0.003
Zirconium.............................................................................0.06
Sulfur .................................................................................0.015
Nickel .............................................................................Balance
HHeeaatt TTrreeaattmmeenntt
Publication Number SMC-095Copyright © Special Metals Corporation, 2004 (Sept 04)
NIMONIC is a trademark of the Special MetalsCorporation group of companies.
NIMONIC alloy 81 is normally used in the solution-and precipitation-treated condition. This heat treatmentis generally carried out in air. Material is usuallysupplied in the solution-treated condition and is aged bythe customer as part of the fabrication process.NIMONIC alloy 81 can, however, be supplied to anyrequested heat-treatment condition. Details of therecommended heat treatments for various forms aregiven below, where the stated times represent the timesat temperature. In establishing furnacing time dueallowance must, of course, be made for furnacecharacteristics and charge weight.
FFoorrmm
Extruded or forged barand section for forging,rolling and /or machining
Hot-rolled plate andsheet
Cold-rolled sheet
SSoolluuttiioonnttrreeaattmmeenntt
8h/1100°C/AC or WQ
approx.½h/1100°C/AC or WQ
5-15min/1100°C/FBQ or WQ
AAggiinnggttrreeaattmmeenntt
16h/700°C/AC
16h/700°C/AC
16h/700°C/AC
Hot-worked products may be cooled from the solution-treatment temperature either by air cooling (AC) or bywater quenching (WQ). Cold-worked products,especially sheet, may be fluidized bed quenched (FBQ):this produces less distortion than water quenchingwithout a significant change in properties.
Interstage annealing to remove residual cold-workis normally applied during manipulation operations.The following treatment is recommended for sheet:
5-15 min/1100°C/AC or WQWelding operations should be carried out with the
alloy in the solution-treated condition. A full, twostage heat treatment should then be applied to developmaximum properties in the welded component.
Details of welding practice are given subsequentlyunder “Fabrication”.
NNIIMMOONNIICC®® aallllooyy 8811
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TTaabbllee 11 - Mean Coefficient of Linear Thermal Expansion
µµmm//mm •• °°CC
20-100
20-200
20-300
20-400
20-500
20-600
20-700
20-800
20-900
20-1000
Mean coefficient of linear expansion between 20°C and temperature shown.
°°CCCCoolldd rroolllleedd sshheeeett
EExxttrruuddeedd aannddssuubbsseeqquueennttllyy ssttrreettcchheedd bbaarr
PPhhyyssiiccaall PPrrooppeerrttiieess
Density, Mg/m3 ............................................................................8.06
lb/in3 ............................................................................0.291
Melting Range
Liquidus temperature, °C.....................................................1375
Solidus temperature, °C ......................................................1305
The exact density value is dependent on compositionalvariation within the release specification, on form, and onheat treatment.
TTaabbllee 22 - Physical Properties
TTeemmppeerraattuurree SSppeecciiffiicc HHeeaatt
°°CC JJ//kkgg••°°CC WW//mm••°°CC
EElleeccttrriiccaall RReessiissttiivviittyy aatt 2200°°CC == 11..2277 µµ ΩΩ •• mm
TThheerrmmaall CCoonndduuccttiivviittyy
RReellaattiivvee RReessiissttaannccee
20
100
200
300
400
500
600
700
800
900
1000
461
461
502
502
544
586
586
628
670
670
712
10.9
12.6
13.8
15.5
17.2
18.4
20.1
21.8
23.4
25.5
27.2
1.000
1.013
1.028
1.043
1.057
1.067
1.068
1.065
1.059
1.050
1.047
11.1
12.5
13.0
13.5
14.0
14.6
15.2
16.3
18.8
19.5
11.7
12.3
12.8
13.2
13.6
14.0
14.4
15.1
16.0
17.4
TTaabbllee 33 - Dynamic Moduli
DDyynnaammiicc YYoouunngg’’ss mmoodduulluuss
20
100
200
300
400
500
600
700
800
900
1000
°°CC
DDyynnaammiiccttoorrssiioonnaallmmoodduulluussEExxttrruuddeedd bbaarr
196
194
188
181
177
170
163
156
147
134
123
212
210
205
199
194
188
181
172
163
150
133
80
79
77
75
72
69
66
62
59
54
48
SShheeeett
GGPPaa GGPPaa GGPPaa
DDyynnaammiicc MMoodduullii
NNIIMMOONNIICC®® aallllooyy 8811
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TTeennssiillee PPrrooppeerrttiieess
Str
ess,
MP
a
Elo
ngat
ion
and
red
uctio
n of
are
a, %
FFiigguurree 11.. Tensile properties of extruded bar subsequently cold stretchedHeat treatment 8h/1100°C/AC + 16h/700°C/ACStrain rate 0.005/min to proof stress (at room temperature) and 0.002/min to proof stress (atelevated temperatures) and 0.1/min thereafter.
Temperature, °C0 200 400 600 800 1000
Temperature, °F
200 400 600 800 1000 1200 1400 1600 1800
Reduction of area
0.2 % proof stress
Tensile Strength
1600
1200
800
400
0
80
60
40
20
0
220
200
180
160
140
120
100
80
60
40
20
0
100
80
60
40
20
0
tonf/in2 103lbf/in2
Elongation
Str
ess,
MP
a
Elo
ngat
ion
and
red
uctio
n of
are
a, %
FFiigguurree 22.. Tensile properties of cold rolled sheetHeat treatment 15 min/1100°C/FBQ or WQ + 16h/700°C/AC
Temperature, °C0 200 400 600 800 1000
Temperature, °F
200 400 600 800 1000 1200 1400 1600 1800
0.2 % proof stress
Tensile Strength
1600
1200
800
400
0
80
60
40
20
0
220
200
180
160
140
120
100
80
60
40
20
0
100
80
60
40
20
0
tonf/in2 103lbf/in2
Elongation
NNIIMMOONNIICC®® aallllooyy 8811
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TTeennssiillee PPrrooppeerrttiieess ((ccoonnttiinnuueedd))
TTaabbllee 44 - Tensile Properties of Autogenously Welded Sheet
All Samples except that tested at 1000°C fractured in the weld.
HHeeaatt ttrreeaattmmeenntt 1155 mmiinn//11110000°°CC//AACC ++ wweelldd ++ 1155 mmiinn//11110000°°CC//AACC ++ 1166 hh//770000°°CC//AACC
EElloonnggaattiioonn,, %%oonn 2255 mmmm oonn 5500 mmmm°°CC
TTeennssiillee SSttrreennggtthhMMPPaa
00..22%% PPrrooooff SSttrreessssMMPPaa
00..11%% PPrrooooff SSttrreessssMMPPaa
20
100
200
400
600
650
700
750
800
850
900
1000
536
551
499
503
403
445
406
425
391
318
158
37
565
570
513
520
423
466
431
442
412
344
168
42
874
860
808
819
641
653
596
598
513
394
229
76
14.0
14.0
16.0
17.0
16.0
13.0
12.0
12.0
10.0
12.0
30.0
96.0
11.5
12.0
14.0
15.0
13.0
9.5
9.5
11.0
8.0
9.5
25.5
62.0
TTaabbllee 55 - Tensile Properties of Filler Metal Welded Sheet
All Samples except those tested at 700°C and 1000°C fractured in the weld.
HHeeaatt ttrreeaattmmeenntt 1155 mmiinn//11110000°°CC//AACC ++ wweelldd ++ 1155 mmiinn//11110000°°CC//AACC ++ 1166 hh//770000°°CC//AACC
EElloonnggaattiioonn,, %%oonn 2255 mmmm oonn 5500 mmmm°°CC
TTeennssiillee SSttrreennggtthhMMPPaa
00..22%% PPrrooooff SSttrreessssMMPPaa
00..11%% PPrrooooff SSttrreessssMMPPaa
20
100
200
400
600
650
700
750
800
850
900
1000
568
537
534
499
494
477
420
419
375
284
170
32
596
558
539
513
508
500
459
448
426
310
190
37
961
978
914
854
791
737
641
571
524
388
238
77
20.0
24.0
21.0
22.0
18.0
14.0
12.0
8.0
6.0
7.0
11.0
66.0
16.0
22.0
17.5
20.0
15.5
11.5
12.0
5.0
4.5
5.0
9.0
56.0
CCrreeeepp PPrrooppeerrttiieess
Typical creep-rupture data for extruded bar subsequentlycold-stretched and heat-treated 4h/1100°C/AC + 16h/700°C/AC are shown by Larson-Miller presentation in Figure 3,and as log stress-log time plots in Figure 4.
Total plastic stain data for bar are shown in Table 6.
BBAARR
Typical creep-rupture data for cold-rolled sheet given therecommended heat treatment of 15 min/1100°C/AC +16h/700°C/AC, are shown by Larson-Miller presentation inFigure 5, and as log stress-log time plots in Figure 6.
Total plastic strain data for sheet are shown in Table 7.
SSHHEEEETT
NNIIMMOONNIICC®® aallllooyy 8811
5
5 10 15 20 25 30 35
°C°F
12002200
2100
11002000
19001000
1800
1700900
1600
8001500
1400
7001300
1200
6001100
1000
500900
800400
700
300600
500
200400
300
100200
20100
2300
10-1 101 102 103 104 105100
Time, Hours
1
1501009080
50
60
708090
10070
60
50
40
30
20
25
30
4025
20
15
151098
10987
6
76
5
45
43
2
1.5
3
2
1.5
1
103
lbf/
in2
MP
a x
101
FFiigguurree 33.. Creep-rupture properties for bar. Fully heat-treated condition.
tonf
/in2
0.4
2.5
2.0
1.5
1.00.90.80.70.6
0.5
20
25
15
109.08.07.0
6.0
5.0
4.0
3.0
7060
50
40
30
Larson-Miller Parameter, T (20 + log t) x 10-3; T in °K, t in hours
NNIIMMOONNIICC®® aallllooyy 8811
6
FFiigguurree 44.. Creep-rupture properties for bar. Fully heat-treated condition.
600°C
Time, hours
Str
ess,
MP
a
1000
900
800
700
600
500
400
300
200
100
90
80
70
60
50
40
30
2010 100 1000 10 000 100 000
500°C
800°C
700°C
140130
120
110
100
90
80
706560
55
50
45
40
35
30282624
22
20
18
16
14
12
10
9
8
7
6
5
4
3
60
55
50
45
40
35
30282624
22
20
18
16
14
12
10
9
8
7
6
5
4
3
2.5
2
1.5
Notched
tonf/in2 103lbf/in2
d
SSttrreessss,, MMPPaa,, ttoo ggiivvee ttoottaall ppllaassttiicc ssttrraaiinn iinn
NNIIMMOONNIICC®® aallllooyy 8811
7
TTaabbllee 66 - Total Plastic Strain Data for Extruded and Subsequently Cold Stretched Bar
The value in parentheses is extrapolated from isothermal curves.
HHeeaatt ttrreeaattmmeenntt 44hh//11110000°°CC//AACC ++ 1166hh//770000°°CC//AACC
TTeesstt TTeemmppeerraattuurree
°°CC 110000hh 330000hh 11000000hh 33000000hh
0.1
0.2
0.5
1.0
0.1
0.2
0.5
1.0
0.1
0.2
0.5
1.0
494
—
564
—
247
286
317
—
94
117
144
—
440
479
510
533
193
239
270
286
59
82
110
119
386
432
448
463
142
185
224
239
31
49
71
82
—
378
402
(402)
—
139
—
—
—
—
—
49
SSttrraaiinn,, %%
770000
880000
660000
NNIIMMOONNIICC®® aallllooyy 8811
8
5 10 15 20 25 30 35
°C°F
12002200
2100
11002000
19001000
1800
1700900
1600
8001500
1400
7001300
1200
6001100
1000
500900
800400
700
300600
500
200400
300
100200
20100
2300
10-1 101 102 103 104 105100
Time, Hours
1
1501009080
50
60
708090
10070
60
50
40
30
20
25
30
4025
20
15
151098
10987
6
76
5
45
43
2
1.5
3
2
1.5
1
103
lbf/
in2
MP
a x
101
FFiigguurree 55.. Creep-rupture properties for sheet. Fully heat-treated condition.
tonf
/in2
0.4
2.5
2.0
1.5
1.00.90.80.70.6
0.5
20
25
15
109.08.07.0
6.0
5.0
4.0
3.0
7060
50
40
30
Larson-Miller Parameter, T (20 + log t) x 10-3; T in °K, t in hours
NNIIMMOONNIICC®® aallllooyy 8811
9
FFiigguurree 66.. Creep-rupture properties for sheet. Fully heat-treated condition.
600°C
Time, hours
Str
ess,
MP
a
1000
900
800
700
600
500
400
300
200
100
90
80
70
60
50
40
30
2010 100 1000 10 000 100 000
650°C
800°C
750°C
700°C
140130
120
110
100
90
80
706560
55
50
45
40
35
30282624
22
20
18
16
14
12
10
9
8
7
6
5
4
3
60
55
50
45
40
35
30282624
22
20
18
16
14
12
10
9
8
7
6
5
4
3
2.5
2
1.5
Plain Heat treatment: 15 min/1100°C/AC+ 16h/700°C/AC
Autogenously welded
Filler metal welded
tonf/in2 103lbf/in2
15 min/1100°C/AC + weld+ 15 min/1100°C/AC+ 16h/700°C/AC
NNIIMMOONNIICC®® aallllooyy 8811
10
SSttrreessss,, MMPPaa,, ttoo ggiivvee ttoottaall ppllaassttiicc ssttrraaiinn iinn
TTaabbllee 77 - Total Plastic Strain Data For Cold-Rolled Sheet
The values in parentheses are extrapolated from isothermal curves.
HHeeaatt ttrreeaattmmeenntt 1155 mmiinn//11110000°°CC//AACC ++ 1166hh//770000°°//AACC
TTeesstt TTeemmppeerraattuurree
°°CC 5500hh 110000hh 330000hh 11000000hh 33000000hh 1100 000000hh
0.1
0.2
0.5
1.0
Rupture
0.1
0.2
0.5
1.0
Rupture
0.1
0.2
0.5
1.0
Rupture
0.1
0.2
0.5
1.0
Rupture
0.1
0.2
0.5
1.0
Rupture
380
480
(600)
—
640
205
335
(455)
—
470
130
185
250
305
355
54
77
119
(155)
210
(16)
25
50
77
140
343
430
520
552
610
170
280
380
(425)
430
105
146
196
238
295
(41)
(56)
84
111
175
—
(15)
32
50
115
(292)
362
437
470
540
(125)
210
285
320
370
(74)
100
133
161
220
—
(34)
(48)
(65)
132
—
—
(15)
(25)
76
(245)
(300)
364
390
465
—
(155)
207
233
295
(51)
(67)
(88)
107
160
—
—
—
(36)
83
—
—
—
—
45
—
(250)
(307)
(330)
365
—
—
(155)
(175)
223
—
—
—
72
108
—
—
—
—
(50)
—
—
—
—
(28)
—
—
—
—
(267)
—
—
—
—
(163)
—
—
—
—
(61)
—
—
—
—
(29)
—
—
—
—
(17)
SSttrraaiinn,, %%
660000
665500
770000
775500
880000
NNIIMMOONNIICC®® aallllooyy 8811
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FFaattiigguuee PPrrooppeerrttiieess
MMeecchhaanniiccaall ffaattiigguuee
Mechanical fatigue for fully heat-treated NIMONIC alloy 81has been examined by the rotating bend technique.Specimens of a minimum diameter of 4.06 mm were testedat 700°C and a nominal 3000 revolutions per minute.
TThheerrmmaall ffaattiigguuee
Thermal fatigue testing of NIMONIC alloy 81 has beencarried out on fully heat-treated tapered-disc specimens of41.3 mm diameter and 0.25 mm edge radius, which werealternately immersed in hot and cold fluidized beds. Meanvalues for the number of cycles to give the firstmicroscopically distinguishable crack are presented inTable 9. These data are compared with NIMONIC alloy80A, given the 8h/1080°C/AC + 16h/700°C/AC heattreatment and tested under the same conditions. Thesuperiority of NIMONIC alloy 81 under these testconditions is clearly demonstrated.
IImmppaacctt DDaattaa
The room temperature Charpy impact strength for NIMONICalloy 81 has been examined on one cast of extruded barsubsequently cold stretched, and heat-treated 4h/1100°C/AC+ 16 h/700°C/AC. A value of 62J was obtained.
The same material was also used to investigate long termembrittlement by room temperature testing.
TTaabbllee 88 - Rotating Bend Fatigue Tests at 700°C
FFaattiigguuee lliiffee
550
463
386
309
SSttrreessssMMPPaa CCyycclleess xx 110066HHoouurrss
0.078
12.6
71.6
357.0
0.014
2.263
12.879
64.250
TTaabbllee 1100 - Room Temperature Charpy V-Notch Impact Tests
SSooaakkiinngg tteerrmmppeerraattuurree,, °°CCSSooaakkiinngg
ttiimmeehh
JJ JJ JJ JJ JJ
73
75
64
47
30
62
61
56
56
—
62
58
54
52
43
72
77
77
81
85
111
103
117
104
—
30
100
1000
3000
10 000
550000 660000 770000 880000 990000
TTaabbllee 99 - Thermal Fatigue Tests Using Taper-Disc Specimens
NNIIMMOONNIICC aallllooyy 8811 NNIIMMOONNIICC aallllooyy 8800AAPPeeaakk
TTeemmppeerraattuurree°°CC MMeeaann ooff nnuummbbeerr ooff ccyycclleess ttoo
iinniittiiaattee ccrraacckkiinngg
876
99
800
900
NNuummbbeerr ooff tteessttss
MMeeaann ooff nnuummbbeerr ooff ccyycclleess ttoo iinniittiiaattee ccrraacckkiinngg
NNuummbbeerr ooff tteessttss
2
2
398
40
3
4
NNIIMMOONNIICC®® aallllooyy 8811
12
CCoorrrroossiioonn RReessiissttaannccee
The oxidation resistance of NIMONIC alloy 81 has beenexamined using the thermobalance technique. The resultsare given in Figure 8.
The effect of exposing NIMONIC alloy 81 for 1000hours in air containing 3% sulfur dioxide is indicated inTable 11, where the weight loss was determined afterelectrolytic descaling in molten caustic soda. Comparabledata for NIMONIC alloy 80A are also given.
The corrosion of NIMONIC alloy 81 in salt mixtures isshown in Table 12. Specimens 19.1 mm long by 12.7 mmdiameter, and having a wet ground surface finish, were usedfor these tests. The weight loss was determined afterelectrolytic descaling in molten caustic soda. Comparabledata for NIMONIC alloy 80A where available are alsoshown.
Additional hot corrosion tests under intermittent saltshower conditions at 800°C are shown in Figure 7.Comparable data for NIMONIC alloy 80A are also given.
Des
cale
d w
eigh
t lo
ss,
mg/
cm2
0
FFiigguurree 77.. Intermittent salt shower corrosion tests (75% Na2 SO4 + 25% NaCl at 800°C)
TTaabbllee 1111 - Gaseous Corrosion in Air/Sulfur Dioxide Mixture
11000000 hhoouurr eexxppoossuurree iinn aaiirr ccoonnttaaiinniinngg 33%% bbyy
vvoolluummee SSOO22.. WWeeiigghhtt lloossss aafftteerr eelleeccttrroollyyttiicc
ddeessccaalliinngg iinn mmoolltteenn ccaauussttiicc ssooddaa,,
mmgg//ccmm22
600
700
800
900
TTeemmppeerraattuurree°°CC
NNIIMMOONNIICC aallllooyy 8800AANNIIMMOONNIICC aallllooyy 8811
1.4
0.7
2.0
3.5
20.0
4.2
–
–
50
100
150
200
250
300
350
60 120 180 240 300
Time, hours
NIM
ON
IC a
lloy
80A
NIMONIC alloy 81
NNIIMMOONNIICC®® aallllooyy 8811
13
WWeeiigghhtt lloossss ((mmgg//ccmm22)) ddeetteerrmmiinneedd aafftteerr eelleeccttrroollyyttiicc ddeessccaalliinngg iinn mmoolltteenn ccaauussttiicc ssooddaa
TTaabbllee 1122 - Salt Mixture Corrosion - Crucible Tests
AAllllooyy
1166hh 330000hh 1166hh 330000hh 1166hh 330000hh 1166hh 330000hh 1166hh 330000hh
0.9
0.8
2
6
—
—
—
—
1
4
13
22
—
1.4
1640
—
0.9
2
4
8
—
1453
1290
1302
4
14
15
32
—
899
1170
—
3
4
3
6
—
—
—
—
20
20
22
76
—
594
1560
—
27
49
46
280
—
—
—
—
84
317
591
861
—
1438
477
—
31
1
13
18
—
—
—
—
15
16
14
21
—
154
86
—
TTeesstt TTeemmppeerraattuurree
NNIIMMOONNIICCaallllooyy8811
NNIIMMOONNIICCaallllooyy8800AA
HHaallff--iimmmmeerrsseeddiinn
NNaa22SSOO44 ++00..55%% NNaaCCll
HHaallff--iimmmmeerrsseeddiinn
NNaa22SSOO44 ++2255%% NNaaCCll
HHaallff--iimmmmeerrsseeddiinn
NNaa22SSOO44 ++2200%% VV220055
HHaallff--iimmmmeerrsseeddiinn
NNaa22SSOO44 ++8800%% VV220055
HHaallff--iimmmmeerrsseeddiinn
NNaa22SSOO44 ++ 2200%% NNaaCCll++ 2200%% VV220055
700
800
900
1000
700
800
900
1000
FFiigguurree 88.. Cyclic oxidation properties of NIMONIC alloys 80A and 81 (Heating cycle: 20 minutes at temperature, 10 minutes at room temperature)
Wei
ght
chan
ge,
mg/
cm2
0
200
Time, hours
400 600 800
-100
-200
-300
-400
NIMONIC alloy 81
NIMONIC alloy 80A
950°C
950°C
1100°C
1100°C
NNIIMMOONNIICC®® aallllooyy 8811
14
TTaabbllee 1133
FFaabbrriiccaattiioonn
HHoott WWoorrkkiinngg
NIMONIC alloy 81 may be hot worked in the temperaturerange 950-1160°C.
CCoolldd WWoorrkkiinngg
Average mechanical properties pertinent to cold formingoperations on annealed sheet, 1.2 mm thick, are given inTable 13.
0.1 % proof stress 414 MPa
0.2 % proof stress 420 MPa
0.5 % proof stress 429 MPa
Tensile strength 897 MPa
Percentage of elongation on 50 mm 38.3
Hardness 230 HV*
Mean grain size ASTM 7
Grain size range ASTM 5.5-8.0
Erichsen value 11.3 mm
Typical plastic anisotropy, R value† 0.93
Shear strength 669 MPa
Ratio of shear to tensile strength 0.75
* A typical hardness range of 200-230 HV is obtained on productionannealed and flattened material.
NIMONIC alloy 81 can be compared with NIMONIC alloy80A in terms of welding response. It is readily welded bythe tungsten inert-gas shielded process (T.I.G. welding) insection thicknesses up to 5 mm but above this thicknessthere is the likelihood of heat-affected-zone cracking. Sheetshould be in the solution-treated condition prior to weldingand the full heat treatment of 5-15 min/1100°C/AC +16h/700°C/AC should be applied after welding. Filler wireof matching composition is normally used and jointefficiencies of at least 90% are obtained.
In laboratory circular fusion weldability testsNIMONIC alloy 81 has been shown to be slightly better thanNIMONIC alloy 80A, particularly under repair weldingconditions. When repair welding fully heat-treated weldmaterial the repair weld can be directly aged withoutcracking whereas under similar conditions NIMONIC alloy80A suffers from heat-affected-zone cracking. Underconditions of severe restraint it may, however, be advisableto apply the solution treatment prior to precipitationhardening after repair welding.
Other welding processes which can be applied toNIMONIC alloy 81 include dip-transfer welding (inthicknesses up to 5 mm), resistance-spot, -stitch, and -seamwelding and flash-butt welding. For these processes theconditions normally used for NIMONIC alloy 80A shouldbe used as a guide for determining the exact weldingparameters. When welding to other NIMONIC alloys thefiller wire used for the stronger member of the combinationshould be used. For example, when welding to NIMONICalloy 90 use NIMONIC filler metal 90. If welding ofNIMONIC alloy 81 to stainless steels or mild steel isrequired, then INCONEL filler metal 82 should be used.
WWeellddiinngg
AAnnnneeaalliinngg
NIMONIC alloy 81 bar or heavy section may be softened bya heat treatment of 2 to 4 hours at 1100°C followed by aircooling. A solution treatment of 8 hours at 1100°C followedby air cooling is recommended prior to precipitationhardening.
Annealing of NIMONIC alloy 81 sheet required duringmanipulation operations should be by heating for 5 to 15minutes at 1100°C followed by rapid cooling: waterquenching for heavier sheet and air cooling for thin section.Fluidized bed quenching may also be used.
† Mean value of plastic anisotropy ratio R for tests at 0°, 45° and 90° to thefinal rolling direction using the formula R = ¼(Ro° + 2R45° + R90°)
The data contained in this publication is for informational purposes only and may be revised at any time without prior notice. The data is believed to be accurate and reliable, butSpecial Metals makes no representation or warranty of any kind (express or implied) and assumes no liability with respect to the accuracy or completeness of the informationcontained herein. Although the data is believed to be representative of the product, the actual characteristics or performance of the product may vary from what is shown in thispublication. Nothing contained in this publication should be construed as guaranteeing the product for a particular use or application.
AAvvaaiillaabbllee PPrroodduuccttss
NIMONIC alloy 81 is available in the following forms,subject to minimum order quantities:
Bars and billets for forgingRods and bars for machiningExtruded sections, rectangular or profile, for
machining, rolling and welding into rings, etc.Hot-rolled plate and sheetCold-rolled sheet and stripCold-worked tubesCold-drawn wire and filler wire
TThhee SSppeecciiaall MMeettaallss CCoorrppoorraattiioonnttrraaddeemmaarrkkss iinncclluuddee::
BRIGHTRAY®
CORRONEL®
DEPOLARIZED®
DURANICKEL®
FERRY®
INCOBAR®
INCOCLAD®
INCO-CORED®
INCOFLUX®
INCOLOY®
INCONEL®
INCOTEST®
INCOTHERM®
INCO-WELD®
KOTHERM®
MONEL®
NILO®
NILOMAG®
NIMONIC®
NIOTHERM®
NI-ROD®
NI-SPAN-C®
RESISTOHM®
UDIMAR®
UDIMET®
601GC®
625LCF®
718SPF™
725NDUR®
800HT®
956HT™
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