AMS 5643
Steel, Corrosion-Resistant, Bars, Wire, Forgings, Tubing, and Rings, 16Cr - 4.0Ni - 0.30Cb - 4.0Cu, Solution Heat Treated, Precipitation Hardenable
Material specification for 17-4PH (UNS S17400) corrosion-resistant steel bars, wire, forgings, tubing and rings, supplied solution heat treated (Condition A) and precipitation hardenable by the user to the H900 through H1150M conditions.
What AMS 5643 specifies
AMS 5643 is the aerospace material specification for 17-4PH (16Cr-4Ni-0.3Nb-4Cu, UNS S17400). Material is delivered solution treated at 1900 ± 25 °F (1038 ± 14 °C) — Condition A, 363 HB (38 HRC) maximum — and the specification defines the ageing treatments and the minimum properties the purchaser's parts must meet: H900 (900 °F / 482 °C, 1 h) 190 ksi (1310 MPa) tensile, 170 ksi (1170 MPa) yield, 10 % elongation, 388 HB / 40 HRC; H925 170/155 ksi; H1025 (4 h) 155/145 ksi and 35 HRC; H1075 145/125 ksi and 32 HRC; H1100 140/115 ksi and 31 HRC; H1150 135/105 ksi, 16 % elongation and 28 HRC; and the double-cycle H1150M (1400 °F for 2 h, then 1150 °F for 4 h) at 115/75 ksi with 18 % elongation for toughness. It also controls composition, melting practice and macrostructure, and requires a heat-treat response test on each lot. Parts are aged under AMS 2759/3.
AMS 5643 types and classes
Every designation the document defines, with the thickness it requires and the tests it imposes.
| Designation | Meaning | Requirement / test |
|---|---|---|
Condition A | Solution treated at 1900 ± 25 °F (1038 °C), as supplied for machining; 363 HB (38 HRC) maximum. | Brinell per ASTM E10 / Rockwell per ASTM E18 |
H900 | Age 900 °F (482 °C) for 1 h, air cool. Minimum 190 ksi (1310 MPa) tensile, 170 ksi (1170 MPa) yield, 10 % elongation, 388 HB / 40 HRC. | Tensile per ASTM E8; hardness per ASTM E10 / E18 |
H925 | Age 925 °F (496 °C) for 4 h. Minimum 170 ksi (1170 MPa) tensile, 155 ksi (1070 MPa) yield, 10 % elongation, 375 HB / 38 HRC. | Tensile per ASTM E8; hardness per ASTM E10 / E18 |
H1025 | Age 1025 °F (552 °C) for 4 h. Minimum 155 ksi (1070 MPa) tensile, 145 ksi (1000 MPa) yield, 12 % elongation, 331 HB / 35 HRC. The usual aerospace balance of strength and toughness. | Tensile per ASTM E8; hardness per ASTM E10 / E18 |
H1075 | Age 1075 °F (579 °C) for 4 h. Minimum 145 ksi (1000 MPa) tensile, 125 ksi (860 MPa) yield, 13 % elongation, 311 HB / 32 HRC. | Tensile per ASTM E8; hardness per ASTM E10 / E18 |
H1100 | Age 1100 °F (593 °C) for 4 h. Minimum 140 ksi (965 MPa) tensile, 115 ksi (795 MPa) yield, 14 % elongation, 302 HB / 31 HRC. | Tensile per ASTM E8; hardness per ASTM E10 / E18 |
H1150 | Age 1150 °F (621 °C) for 4 h. Minimum 135 ksi (930 MPa) tensile, 105 ksi (725 MPa) yield, 16 % elongation, 277 HB / 28 HRC. | Tensile per ASTM E8; hardness per ASTM E10 / E18 |
H1150M | Age 1400 °F (760 °C) for 2 h, air cool, then 1150 °F (621 °C) for 4 h. Minimum 115 ksi (795 MPa) tensile, 75 ksi (515 MPa) yield, 18 % elongation; the toughest condition. | Tensile per ASTM E8; hardness per ASTM E10 / E18 |
Tests and the drawing call-out
Tests the document imposes
- Heat-treat response: tensile per ASTM E8/E8M after the specified age on each lot
- Hardness per ASTM E10 (Brinell) or ASTM E18 (Rockwell C)
- Chemical analysis per ASTM E353 or spectrographic methods
- Macrostructure / macro-etch and grain flow on forgings
- Ultrasonic inspection per AMS-STD-2154 when specified
How to cite it
Drawing call-out
MATERIAL: 17-4PH BAR PER AMS 5643, CONDITION A; HEAT TREAT TO H1025 PER AMS 2759/3, 35 HRC MINAngle brackets mark the choices the drawing must make; every finish page shows a completed example.
Heat treatments specified to AMS 5643
| Treatment | Role | Cost |
|---|---|---|
Q+T H1025 is a precipitation-hardening condition for 17-4 PH (S17400) and 15-5 PH (S15500). | Governing | $$ |
Q+T H1075 is a precipitation-hardening condition for 17-4 PH (S17400) and 15-5 PH (S15500). | Governing | $$ |
Q+T H1150 is a precipitation-hardening condition for 17-4 PH (S17400) and 15-5 PH (S15500). | Governing | $$ |
Q+T H900 is a precipitation-hardening condition for 17-4 PH (S17400) and 15-5 PH (S15500). | Governing | $$ |
AMS 5643 — frequently asked
Why buy Condition A and age after machining?
Condition A is soft enough (38 HRC maximum) to machine economically, and the age produces a predictable contraction — about 0.0004–0.0006 in/in for H900 and up to about 0.001 in/in for H1150 — so parts can be finished before ageing with a small allowance. Buying pre-hardened bar makes sense only for small parts finished by grinding.
Which condition should I pick?
H900 for maximum strength where stress-corrosion exposure is low; H1025 as the aerospace default balance; H1075 and H1100 for better toughness and SCC resistance; H1150 and H1150M where impact strength or low-temperature toughness governs. Conditions below H1025 are generally avoided in seawater or hydrogen service.
What is the difference between AMS 5643 and ASTM A564 Type 630?
Same alloy, same H conditions and minimum properties, but AMS 5643 adds aerospace controls: consumable-electrode remelting, macrostructure and forging grain-flow requirements, a heat-treat response test on every lot and AMS 2750 pyrometry. Aerospace drawings cite AMS 5643 (or AMS 5622 for the premium-quality grade); industrial drawings cite A564.
Can Condition A parts be welded and then aged?
Yes. 17-4PH welds readily and the weld zone hardens with the base metal in the age, but the heat-affected zone may need a re-solution treatment first if uniform properties are required, and welded parts are usually aged at H1025 or higher to keep the weld tough.
AMS 5643 is copyrighted by SAE International. This page explains the document so a drawing can be read; it does not reproduce the standard. Purchase the current edition from the publisher. Official source ↗