Incoloy 925 Fasteners

INCOLOY® Alloy 925 (UNS N09925) is an agehardenable nickel-iron-chromium alloy with additions of molybdenum, copper, titanium and aluminum. The alloy’s chemical composition, listed in Table 1, is designed to provide a combination of high strength and excellent corrosion resistance. The nickel content is sufficient for protection against chloride-ion stresscorrosion cracking. The nickel, in conjunction with the molybdenum and copper, also gives outstanding resistance to reducing chemicals. The molybdenum aids resistance to pitting and crevice corrosion. The alloy’s chromium content provides resistance to oxidizing environments. The titanium and aluminum additions cause a strengthening reaction during heat treatment.
INCOLOY Alloy 925 is used in various applications requiring a combination of high strength and corrosion resistance. Because of the alloy’s resistance to sulfide stress cracking and stress-corrosion cracking in “sour” (H2S containing) crude oil and natural gas, it is used for down-hole and surface gaswell components including tubular products, valves, hangers, landing nipples, tool joints and packers. The alloy is also useful for fasteners, marine and pump shafting and high-strength piping systems.

INCOLOY Alloy 925 Chemical Composition

Nickel	42.0-46.0
Chromium	19.5-22.5
Iron	22 min
Molybdenum	2.5-3.5
Copper	1.5-3.0
Ttianium	1.9-2.4
Aluminum	0.1-0.5
Manganese	1.0 max.
Silicon	0.5 max.
Niobium	0.5 max.
Carbon	0.03 max.
Sulfur	0.03 max.

Elevated Temperature Dynamic Young's Modulus and Shear Modulus Values for INCOLOY Alloy 925 (hot rolled round, solution-annealed and aged)

Temperature		Young s Modulus		Shear Modulus		Poisson s Ratio
F	C	10 3 ksi	GPa	10 3 ksi	GPa	Poisson s Ratio
70	21	28.9	199	11.2	77	0.293
100	38	28.8	199	11.1	76	0.299
200	93	28.3	195	10.8	75	0.308
300	149	27.8	192	10.6	73	0.316
400	204	27.3	188	10.4	72	0.315
500	260	26.8	185	10.2	70	0.317
600	316	26.3	182	10	69	0.319
700	371	25.9	178	9.8	68	0.319
800	427	25.4	175	9.6	66	0.323
900	482	24.9	172	9.4	65	0.323
1000	538	24.4	168	9.2	64	0.324
1100	593	23.8	164	9	62	0.326
1200	649	23.2	160	8.7	60	0.33
1300	704	22.5	155	8.4	58	0.334
1400	760	21.8	150	8.2	56	0.338
1500	816	21	145	7.9	54	0.335
1600	871	20.1	139	7.6	52	0.33
1700	927	19.2	132	7.2	50	0.326

Thermal Properties of INCOLOY Alloy 925

Temperature	Coefficient of Expansion a	Specific Heat
F	10 -6 in/in F	Btu/lb F
70	-	0.104
200	7.8	0.109
400	8.1	0.116
600	8.4	0.122
800	8.5	0.129
1000	8.7	0.136
1200	9	0.143
1400	9.5	0.15
1600	-	0.157
Temperature	Coefficient of Expansion a	Specific Heat
C	m m/m C	J/kg C
20	-	435
100	13.2	456
200	14.2	486
300	14.7	507
400	15	532
500	15.3	561
600	15.7	586
700	16.3	611
800	17.2	641
900	-	666

Temperature		Thermal Conductivity
C	F	W/m C	BTU in/ft 2 h F
23	73	12	83.1
100	212	12.9	89.2
200	392	14.3	99.2
300	572	15.9	110
400	752	17.4	120.9
500	932	19.3	133.8
600	1112	22.2	153.7
700	1292	24	166.7
800	1472	28.2	195.8
900	1652	27.7	192.3
1000	1832	24.6	170.7
1100	2012	26	180.2
1150	2102	26.9	186.8

INCOLOY Alloy 925 Mechanical Properties

Physical Properties of INCOLOY Alloy 925

Density,	lb/in3	0.292
Density,	g/cm3	8.08
Melting Range,	F	2392-2490
Melting Range,	C	1311-1366
Electrical Resistivity,	ohm cmil/ft	701
Electrical Resistivity,	µΩ m	1.17
Permeability at 200 oersteds (15.9 kA/m)		1.001

Tensile Properties of INCOLOY Alloy 925

Form/Condition	Tensile Strength		Yield Strength (0.2% Offset)		Elongation %	Hardness* Rockwell
Form/Condition	ksi	MPa	ksi	MPa	Elongation %	Hardness* Rockwell
Round/Solution-Annealed	99.3	685	39.3	271	56	76 B
Round/Solution-Annealed and Aged	167.3	1154	120.6	832	27	32 C
Cold Drawn Tubing/Solution- Annealed and Aged	172.5	1189	120.4	830	27	35 C

Limits for INCOLOY Alloy 925, Solution-Annealed and Aged Material (SMC internal specification HA 46)

Condition	Diameter		Tensile Strength minimum		Yield Strength (0.2% offset) minimum		Elongation in 2 in (50.8 mm) or 4D min. %	Reduction of Area minimum %	Impact Strength 1 min. average		Hardness 2 Rockwell C
Condition	in	mm	ksi	MPa	ksi	MPa	Elongation in 2 in (50.8 mm) or 4D min. %	Reduction of Area minimum %	ft lbf	kgf m	min.	max.
Cold Worked	5/8 to 3.0	15.9 to 76.2	140	965	105	724	18	25	35	4.85	26	38
Hot Worked	1 to 10	25.4 to 254	140	965	110	758	18	25	35	4.85	26	38

Rotating beam fatigue data for INCOLOY alloy 925 and MONEL alloy K-500.

Mean axial stress vs. cycles of fatigue for INCOLOY alloy 925 in the 1365 F (740 C) dual aged condition. Tension-tension test.

Metallurgy

INCOLOY alloy 925 is an austenitic nickel-iron-chromium alloy made precipitation hardenable by additions of titanium and aluminum. The precipitation-hardening (agehardening) heat treatment causes precipitation of gamma prime phase, Ni3 (Al, Ti). The phase greatly increases both the hardness and strength of the alloy. Exposure to elevated temperatures also causes formation of other phases, including eta and sigma. Figure 4 is a time-temperature-transformation diagram, and Figure 5 shows effects of the phases on impact strength of the solution-annealed plus aged alloy.

Figure 4. Time-temperature-transformation diagram for initially solution-annealed INCOLOY alloy 925 material.

Figure 5. Effect of high-temperature exposure on impact strength of solution-annealed INCOLOY alloy 925 material. Base impact strength was 236 ftlbf (320 J).

Corrosion Resistance

Results of autoclave C-ring tests in a solution of distilled water containing 25% sodium chloride, 0.5% acetic acid and 1 g/l sulfur with pressure of 120 psi (827 kPa) hydrogen sulfide. Test stresses were 100% of yield strength (0.2% offset).

INCOLOY alloy 925 has a high level of corrosion resistance. In both reducing and oxidizing environments, the alloy resists general corrosion, pitting, crevice corrosion, intergranular corrosion and stress-corrosion cracking. Some environments in which INCOLOY alloy 925 is particularly useful are “sour” (H2S containing) crude oil and natural gas, sulfuric acid, phosphoric acid, and seawater.

C-Ring Tests in NACE Solution^a

Alloy	Material Condition	Simulated Wel Age	Yield Strength (0.2% Offset)		Hardness	Duration	Sulfide Stress Cracking
Alloy	Material Condition	Simulated Wel Age	ksi	MPa	Rockwell C	Days	Sulfide Stress Cracking
INCONEL alloy 625	Cold Worked	None	125	862	30.5	42	No
	Cold Worked	None	160	1103	37.5	10	Yes
	Cold Worked	None	176	1214	41	6	Yes
INCONEL alloy 718	Age Hardened	None	120	827	30	42	No
	Age Hardened	None	130	896	37	42	No
	Age Hardened	None	134	924	38.5	42	No
	Age Hardened	None	139	958	38	42	No
	Age Hardened	None	156	1076	41	60	No
INCONEL alloy 725	Cold Worked	None	90	621	25	30	No
	Age Hardened	None	117.6	811	37	30	No
	Age Hardened	None	128.6	887	40	30	No
	Age Hardened	600 F (315 C)/1000 h	130.8	902	41.5	30	No
	Age Hardened	None	132.9	916	36	42	No
	Age Hardened	None	133	917	39	30	No
	CW & Aged	None	137.8	950	39	42	No
INCOLOY alloy 825	Cold Worked	None	138	952	30	42	No
INCOLOY alloy 825	Cold Worked	None	147	1014	33	42	No
INCOLOY alloy 925	Age Hardened	None	114	786	38	42	No
	Cold Worked	None	139	958	35.5	42	No
	CW & Aged	None	176	1214	43.5	42	No
	CW & Aged	None	186	1282	46	42	No
	Age Hardened	500 F (260 C)/500 h	113.5	783	38	42	No
	Cold Worked	500 F (260 C)/500 h	139.5	962	35.5	42	No
	CW & Aged	500 F (260 C)/500 h	176	1214	43.5	42	No
	CW & Aged	500 F (260 C)/500 h	180	1214	44	42	No
	CW & Aged	500 F (260 C)/500 h	185.5	1279	46	42	No
Alloy G-3	Cold Worked	600 F (315 C)/1000 h	119.4	823	26	43	No
	Cold Worked	600 F (315 C)/1000 h	132.3	912	30	43	No
	Cold Worked	600 F (315 C)/1000 h	135.3	933	31	43	No
	Cold Worked	600 F (315 C)/1000 h	136.9	944	-	30	No, No b
	Cold Worked	600 F (315 C)/1000 h	137.7	949	-	30	No, No b
	Cold Worked	600 F (315 C)/1000 h	181.7	1253	-	30	No, Yes b
Alloy C-276	Cold Worked	600 F (315 C)/1000 h	126.6	873	32	43	No
	Cold Worked	600 F (315 C)/1000 h	155.1	1069	38	43	No
	Cold Worked	600 F (315 C)/1000 h	166.8	1150	35	43	No
	Cold Worked	600 F (315 C)/1000 h	188.7	1301	43	43	No
a Room-temperature tests at 100% of yield strength in 5% NaCl plus 0.5% acetic acid saturated with H2S. All specimens were couple to carbon steel. b Duplicate test specimens.

Stress-Corrosion-Cracking Testsa in High-Temperature Sour Environments

Alloy	Material Condition	Yield Strength (0.2% offset)		Hardness	Test Media ^b	Duration	Stress Corrosion Cracking
Alloy	Material Condition	ksi	MPa	Rockwell C	Test Media ^b	Days	Stress Corrosion Cracking
INCONEL alloy 625	Cold Worked	128	883	37	A	15	No
	Cold Worked	177.1	1221	41	A	15	No
	Cold Worked	128	883	37	B	15	No
	Cold Worked	177.1	1221	41	B	15	No
	Cold Worked	125	862	30.5	C	42	No
	Cold Worked	160	1103	37.5	C	42	No
	Cold Worked	176	1214	41	C	42	No
INCONEL alloy 718	Age Hardened	120	827	30	C	42	No
	Age Hardened	134	924	38.5	C	42	No
	Cold Worked	197	1358	37.5	C	20	Yes
INCOLOY alloy 825	Cold Worked	131	903	30	A	15	Yes
	Cold Worked	138	952	30	C	42	No
	Cold Worked	147	1014	33	C	42	No
INCOLOY alloy 925	CW & Aged	166	1145	40.5	A	15	Yes
	Age Hardened	113.5	783	38	B	15	Yes
	CW & Aged	185.5	1279	46	B	15	Yes
	Age Hardened	114	786	38	C	42	No
	Cold Worked	139	958	35.5	C	42	No
	CW & Aged	176	1214	43.5	C	42	No
	CW & Aged	185.5	1279	46	C	42	No
Alloy G-3	Cold Worked	133.5	920	33	D	60	No
	Cold Worked	133.5	920	33	D	120	No
	Cold Worked	137.5	948	30	D	90	Yes
	Cold Worked	137.5	948	30	D	120	No
	Cold Worked	183.3	1264	38	D	120	No
	Cold Worked	133.5	920	33	E	60	No
	Cold Worked	133.5	920	33	E	120	No
	Cold Worked	137.5	948	30	E	120	No
	Cold Worked	183.3	1264	38	E	120	No
Alloy C-276	Cold Worked	194.7	1342	43.5	A	15	No
Alloy C-276	Cold Worked	194.7	1342	43.5	B	15	No
a Autoclave tests on C-ring specimens stressed at 100% of yield strength. b Test Media: A = 15% NaCl plus 200 psi (1380 kPa) H2S plus 100 psi (690 kPa) CO2 plus 1 g/l of sulfur at 450 F (232 C). B = 25% NaCl plus 200 psi (1380 kPa) H2S plus 100 psi (690 kPa) CO2 plus 1 g/l of sulfur at 400 F (204 C). C = 15% NaCl saturated with H2S plus 1000 psi (6.9 MPa) gas phase of 1% H2S, 50% CO2, 49% N2 at 500 F (260 C). D = 25% NaCl plus 100 psi (690 kPa) H2S plus 200 psi (1380 kPa) CO2 at 400 F (204 C). E = Same as D but at 425 F (218 C).

Corrosion Testsa of INCOLOY alloy 925 in Free-Sulfur Environments

Alloy	Test Media b	Corrosion Rate
Alloy	Test Media b	mpy	mm/a
Alloy C-276	A	0.2	0.005
Alloy C-276	B	0.1	0.003
INCONEL alloy 625	A	0.7	0.018
INCONEL alloy 625	B	0.2	0.005
INCOLOY alloy 925	A	1.1	0.028
INCOLOY alloy 925	B	1.2	0.03
INCOLOY alloy 825	A	1.1	0.028
INCOLOY alloy 825	B	1.6	0.041
AISI Type 316	A	3.9	0.099
AISI Type 316	B	4.5	0.114
a Autoclave tests of 15-day duration on unstressed coupons. b Solution A: 15% NaCl plus 200 psi (1380 kPa) H2S plus 100 psi (690 kPa) C O2 plus 1 g/l of sulfur at 450 F (232 C). Solution B: 25% NaCl plus 200 psi (1380 kPa) H2S plus 100 psi (690 kPa)

Corrosion rates for INCOLOY alloy 925 solution-annealed and aged 0.125 in sheet, evaluated in acid environments for varied exposure time and temperatures as per MTI Manual No.3 procedures

Environment	Temperature		Corrosion Rate
	Temperature		0-192 h
	C	F	mpy	mm/a
0.2% HCl	Boiling	Boiling	<0.1	<0.01
1% HCl	70	158	11	0.28
10% H₂SO₄	70	128	2	0.05
85% H₂PO₄	Boiling	Boiling	47	1.19
	90	194	<1	<0.03
80% CH₃CO₂H	Boiling	Boiling	<0.1	<0.01

Weld Impact Properties at Room Temperature for INCOLOY alloy 925, Welded with INCO-WELD Filler Metal 725NDUR

Heat Treat Condition		Welding Process	Charpy V-Notch Impact Strength Average		Charpy V-Notch Impact Strength Exposed at 1000 F (538 C) for 1000 h
Pre-Weld	Post-Weld	Welding Process	ft/lbf	J	ft/lbf	J
Anneal	Age	GTAW	19	26	16.5	22
Anneal	Anneal+ Age	GTAW	42	57	37.5	51
Age	Age	GTAW	19	26	11.5	16
Anneal	Age	GMAW	20	27	15	20
Anneal	Anneal + Age	GMAW	35	47	28.5	39
Age	Age	GMAW	20	27	15	20
Anneal = 1900 F (1040 C)/1 h/AC Age = 1365 F (740 C)/6-9 h/FC to 1150 F (621 C) -15 F (8 C) for a total aging time of 18 h.

Figure 7. INCOLOY alloy 925 GTA weld data. Pre-weld treatment: anneal. Post-weld treatment: anneal plus age.
Note: Anneal = 1900 F (1040 C)/1 h/AC. Age = 1365 F (740 C)/6-9 h/FC to 1150 F (621 C) -15 F (8 C) for a total aging time of 18 h.

Figure 8. INCOLOY alloy 925 GTA weld data. Pre-weld treatment: anneal. Post-weld treatment: age.
Note: Anneal = 1900°F (1040°C)/1 h/AC. Age = 1365°F (740°C)/6-9 h/FC to 1150°F (621°C) ±15°F (8°C) for a total aging time of 18 h.

Figure 9. INCOLOY alloy 925 GTA weld data. Pre-weld treatment: age. Post-weld treatment: age.
Note: Anneal = 1900 F (1040 C)/1 h/AC. Age = 1365 F (740 C)/6-9 h/FC to 1150 F (621 C) -15 F (8 C) for a total aging time of 18 h.

Figure 10. INCOLOY alloy 925 GMA weld data. Pre-weld treatment: anneal. Post-weld treatment: anneal plus age.
Note: Anneal = 1900 F (1040 C)/1 h/AC. Age = 1365 F (740 C)/6-9 h/FC to 1150 F (621 C) -15 F (8 C) for a total aging time of 18 h.

Figure 11. INCOLOY alloy 925 GMA weld data. Pre-weld treatment: anneal. Post-weld treatment: age.
Note: Anneal = 1900 F (1040 C)/1 h/AC. Age = 1365 F (740 C)/6-9 h/FC to 1150 F (621 C) -15 F (8 C) for a total aging time of 18 h.

Figure 12. INCOLOY alloy 925 GMA weld data. Pre-weld treatment: age. Post-weld treatment: age.
Note: Anneal = 1900 F (1040 C)/1 h/AC. Age = 1365 F (740 C)/6-9 h/FC to 1150 F (621 C) -15 F (8 C) for a total aging time of 18 h.

Machining data for INCOLOY alloy 925 Tool Material

		Annealed	Aged
App. hardness range (Rockwell)		80Rb	40Rc
Depth of cut	in	0.25	0.05
Depth of cut	mm	6.4	1.3
High speed steel
Surface speed	ft/min	40-50	15-20
Surface speed	m/min	12-15	4-6
Feed	in/rev	0.03	0.008
Feed	mm/rev	0.8	0.2
Tool material		T-5	M-36
Carbide
Surface speed - Brazed tool	ft/min	175-225	40-50
Surface speed - Brazed tool	m/min	53-69	12-15
Surface speed - Throw away	ft/min	200/250	50/100
Surface speed - Throw away	m/min	61-76	15-30
Feed	in/rev	0.02	0.008
Feed	mm/rev	0.5	0.2
Tool material		C-6	C-2
Note: Water base-oil emulsion or chemical solution is used as cutting fluid