This specification covers hot- and cold-worked precipitation-hardenable nickel alloy rod,
bar, forgings, and forging stock for moderate or high temperature service (Table 1).
The values stated in inch-pound units are to be regarded as standard, The values given
in parentheses are mathematical conversions to SI units that are provided for information
only and are not considered standard.
The material shall conform to the requirements as to chemical composition prescribed in
Table
1.
If a product (check) analysis is performed by the purchaser, the material shall conform
to
the product (check) analysis variations prescribed in Specification B880.
| Element | Composition Limits, % | |||||
|---|---|---|---|---|---|---|
| UNS N07750 (Formerly Grade 688) | ||||||
| Carbon | 0.08 max | |||||
| Manganese | 1.00 max | |||||
| Silicon | 0.50 max | |||||
| Phosphorus | ... | |||||
| Sulfur | 0.01 max | |||||
| Chromium | 14.00-17.00 | |||||
| Cobalt | 1.00 maxA | |||||
| Molybdenum | ... | |||||
| Columbium (Nb) + tantalum | 0.70-1.20 | |||||
| Titanium | 2.25-2.75 | |||||
| Aluminum | 0.40-1.00 | |||||
| Zirconium | ... | |||||
| Boron | 5.00-9.00 | |||||
| Iron | ... | |||||
| Copper | 0.50 max | |||||
| Nickel | 70.00 min | |||||
A. If determined.
B. The element shall be determined arithmetically by difference.
1) Unless otherwise specified, the material shall be supplied in the cold worked or solution
treated condition, suitable for subsequent age hardening.
The cold worked or solution
treated material shall be capable of meeting the mechanical property requirements of Table
3, and the stress rupture lequirements of Table 4 (except alloys UNS N07022, N09925 and
N07725), following the precipitation hardening treatment described in Table 2.
3) When the material is to be supplied in the cold worked or solution treated plus aged
condition, the requirements of Table 3 and Table 4 (except alloys UNS N07022, N09925 and
N07725) shall apply, with the precipitation hardening treatment of Table 2, or as agreed
upon between the purchaser and the manufacturer as part of the purchase contract,
| Alloy | Recommended Annealing Treatment |
Recommended Solution Treatment |
Recommended Stabilizing Treatment |
Precipitation Hardening Treatment |
|---|---|---|---|---|
| N07750 Type 1 (Service above 11OO°F) (593°C) | ... | 2100 ± 25 °F (1149 ± 14°C), hold 2 to 4 h, air cool | 1550 ± (843 ± 14 °C), hold 24 h, air cool | 1300 ± 250 °F (704 ± 14°C), hold 20 h, air cool or furnace cool |
| N07750 Type 2 (Service up to 1100°F) (593°C) | ... | 1800 ± 25°F (982 ± 14°C), hold 1/2 h min, cool at rate equivalent to air cool or faster. | ... | 1350 ± 25°F (732 ± 14°C), hold 8 h, furnace cool to 1150 ± 25°F (62 1 ± 14°C), hold until total precipitation heat treatment has reached 18 h, air cool |
| N07750 Type 3 | ... | 1975 - 2050°F (1079-1121°C), hold 1 to 2 h, air cool. | ... | 1300 ± 25°F (704 ± 14°C), hold 20 h, + 4 — O h, air cool. |
| Alloy | Heat Treatment | Tensile Strength, min, psi [MPa] | Yield Strength (0.2 % offset), min, psi [MPa] | Elongation in 2 in. [50 mm] or 4D, min, % | Reduction of Area, min, % | Brinell Hardness |
|---|---|---|---|---|---|---|
| N07750 Type 1 | solution at 2100°F [1149°C] + stabilize + precipitation harden | 140 000 [965] | 90 000 [620] | 8 | ... | 262 min |
| N07750 Type 2C | solution at 1800°F [982°C] + precipitation harden | 170 000 [1170] | 115 000 [790] | 18 | 18 | 302 to 363 |
| N07750 Type 2D | solution at 1800°F [982°C] + precipitation harden | 170 000 [1170] | 115 000 [790] | 15 [10]E | 15 [12]E | 302 to 363 |
| N07750 Type 3 | solution anneal at 2000°F [1093°C] + precipitation harden | 160 000 [1103], min 185 000 [1276], max | 100 000 [689], min 130 000 [896], max | 20 | 20 | 267-363, Bm 27-40, Rc |
A. The supplier shall demonstrate that the material will meet fully heat-treated properties
after full heat treatment in accordance with Table 2.
B. Forgings.
C. Up to 2.50 in. [63.5 mm], exclusive.
D. 2.50 to 4.00 in. [63.5 to 101.6 mm], exclusive.
E. These values apply for tension specimens machined tangentially from near the center of
large disk forgings over 50 in.2 [3225.8 mm2] in cross section or radially from rings 3 in.
[76.2 mm] or more in thickness.
F. Cold worked, solution annealed and aged, 0.625 in. [15.9 mm] to 3 in. [76.2 mm],
inclusive.
G. Hot worked, solution annealed and aged, 1 in. [25.4 mm] or over.
| Alloy | Heat Treatment | Test Treatment F(C) |
Stress, psi (MPa) B |
Minimum Hours | Elongation in 2 in. or 50mm(or 4D), min,% |
|---|---|---|---|---|---|
| N07750 Type 1 | N07750 Type 1 solution at 2100°F (114900) + stabilize + precipitation 1350 45 000 100 5 (3 if hours exceed harden | 1350 (732) |
45000 (310) |
100 | 5 (3 if hours exceed harden 136) |
Chemical Analysis—One test per lot.
Tension—One test per lot,
Hardness—One test per lot.
Stress-Rupture—One test per lot.
Determine the chemical composition and mechanical and other properties of the material as enumerated in this specification, in case of disagreement, in accordance with the following methods:
| Test | ASTM Desigination |
|---|---|
| Chemical Analysis | E1473 |
| Tension | E8/E8M |
| Rounding Procedure | E29 |
| Stress-rupture | E139 |
| Hardness Conversion | El 40 |
For purposes of determining compliance with the specified limits for requirements of the properties listed in the following table, an observed value or a calculated value shall be rounded in accordance with the rounding method of Practice E29,
| Test | Rounded Unit for Observed Or Calculated Value |
|---|---|
| Chemical composition, Nearest unit in the last righthand place of figures of the pressed in decimals), specified limit. If choices and hardness | Nearest unit in the last righthand place of figures of the pressed in decimals), specified limit. If choices and hardness are possible, as when the digits dropped are exactly a 5 or a 5 followed only by zeros, choose the one ending in an even digit, with zero defined as an even digit. |
| Tensile strength and yield strength | Nearest 1000 psi (6.9 MPa) |
| Elongation | Nearest 1% |
| Rupture life | 1h |
When specified in the purchase order or contract, a producer's or supplier's certification shall be furnished to the purchaser that the material was manufactured, sampled, tested, and inspected in accordance with this specification and has been found to meet the requirements. When specified in the purchase order or contract, a report or the test results shall be furnished.
| Standard | Documents |
|---|---|
| B880 | Specification for General Requirements for Chemical Check Analysis Limits for Nickel, Nickel Alloys and Cobalt Alloys |
| E8/E8M | Test Methods for Tension Testing of Metallic Materials |
| E29 | Practice for Using Significant Digits in Test Data to Determine Conformance with Specifications |
| El 39 | Test Methods for Conducting Creep, Creep-Rupture, and Stress-Rupture Tests of Metallic Materials |
| El 4() | Hardness Conversion Tables for Metals Relationship Among Brinell Hardness, Vickers Hardness, Rockwell Hardness, Superficial Hardness, Knoop Hardness, Scleroscope Hardness, and Leeb Hardness |
| E 1473 | Test Methods for Chemical Analysis of Nickel, Cobalt and High-Temperature Alloys |