Project Description
17-7PH (UNS S17700), also designated as 1.4568, X7CrNiAl17-7, SUS631, and 07Cr17Ni7Al, is a semi-austenitic precipitation hardening (PH) stainless steel combining high strength with excellent corrosion resistance and good formability in the solution-annealed condition. Its unique hardening mechanism — achieved through a low-temperature aging treatment rather than conventional martensitic transformation — produces minimal distortion, making it ideal for precision components in the oil and gas industry. SHUNFU METAL, certified to ISO 9001:2015 and API Q1, manufactures 17-7PH stainless steel bars under strict process controls — from electric arc furnace (EAF) melting with argon oxygen decarburization (AOD) refining through precision hot rolling and forging — ensuring consistent chemistry, microstructure, and mechanical properties for demanding oilfield environments.
17-7PH Stainless Steel Bar — Overview
Developed for applications requiring a combination of high tensile strength (up to 1586 MPa in Condition RH 950), good ductility, and resistance to stress corrosion cracking, 17-7PH has become a standard material for valve stems, pump shafts, wellhead fasteners, downhole springs, compressor components, and subsea instrumentation throughout the petroleum sector. The alloy derives its strength from a martensitic matrix strengthened by NiAl intermetallic precipitates formed during aging. At SHUNFU METAL, every production lot undergoes in-house optical emission spectrometry (OES) verification and full mechanical testing, with MTC documentation per EN 10204 Type 3.1 provided as standard.
17-7PH Equivalent Grades — International Standards
| Standard | Designation |
|---|---|
| ASTM A564 | Grade 631 / UNS S17700 |
| AMS | AMS 5644 (bar), AMS 5528 (sheet) |
| EN 10088-3 / DIN | 1.4568 / X7CrNiAl17-7 |
| JIS G4303 | SUS631 |
| GOST 5632 | 09Х17Н7Ю |
| GB/T 1220 | 07Cr17Ni7Al |
SHUNFU METAL supplies 17-7PH bars certified to ASTM A564, AMS 5644, EN 10088-3, and GB/T 1220 with full heat traceability and API Q1 documentation.
SHUNFU METAL
17-7PH Applications — Oil & Gas Industry
The high strength-to-weight ratio, excellent fatigue resistance, and reliable performance in mildly corrosive wellbore fluids make 17-7PH a preferred material for critical oilfield equipment. SHUNFU METAL supplies 17-7PH bars to manufacturers of the following petroleum components, with every heat verified against specification requirements:
Supply Range — 17-7PH Bar Dimensions
SHUNFU METAL maintains comprehensive production capability for 17-7PH bars across hot-rolled, cold-finished, and forged forms, processed through ISO 9001:2015 controlled workflows with ultrasonic testing available upon request. The following dimensional ranges are offered as standard, with custom sizes accommodated through our in-house forging and machining facilities:
| Product Form | Diameter / Thickness Range | Width Range | Length (Standard) | Condition |
|---|---|---|---|---|
| Hot Rolled Round | 10 mm – 300 mm | — | 3000 – 6000 mm | Solution Annealed (Condition A) |
| Cold Finished / Peeled Round | 3 mm – 100 mm | — | 2000 – 6000 mm | Condition A, TH 1050, RH 950 |
| Hot Rolled Flat | 10 mm – 150 mm | 50 mm – 500 mm | 2000 – 6000 mm | Solution Annealed (Condition A) |
| Forged Round | 100 mm – 800 mm | — | 1000 – 6000 mm | Solution Annealed (Condition A) |
| Forged Flat / Block | 50 mm – 400 mm | 100 mm – 1000 mm | 1000 – 5000 mm | Solution Annealed (Condition A) |
All bars are supplied with EN 10204 Type 3.1 Mill Test Certificates documenting heat number, chemical analysis, mechanical test results, and dimensional compliance. Ultrasonic testing per ASTM A388 / EN 10228-3 is available on request.
17-7PH Chemical Composition per ASTM A564
At SHUNFU METAL, each heat of 17-7PH is verified by in-house optical emission spectrometry (OES) against the ASTM A564 / AMS 5644 composition limits prior to hot working. The chromium-nickel-aluminum balance is tightly controlled to ensure consistent precipitation hardening response, with API Q1 certified traceability from melt to finished bar:
| Element | C | Mn | Si | P | S | Cr | Ni | Al |
|---|---|---|---|---|---|---|---|---|
| Wt % | 0.09 max | 1.00 max | 1.00 max | 0.040 max | 0.030 max | 16.00–18.00 | 6.50–7.75 | 0.75–1.50 |
Composition conforms to ASTM A564 Grade 631 (UNS S17700) and AMS 5644. The carefully controlled aluminum addition (0.75–1.50%) is the key alloying element responsible for gamma prime (Ni3Al) precipitate formation during aging, which delivers the alloy’s characteristic high strength.
17-7PH Mechanical Properties by Heat Treatment
The mechanical performance of 17-7PH stainless steel bars is governed by the heat treatment condition. SHUNFU METAL performs in-house tensile testing (ASTM E8) and Rockwell hardness testing (ASTM E18) on every production lot, with full results documented on the MTC. The following values represent minimum guaranteed properties per AMS 5644 for bar products:
| Condition | Tensile Strength (MPa / ksi) |
Yield Strength (0.2% offset, MPa / ksi) |
Elongation (% in 4D) |
Reduction of Area (%) |
Hardness (HRC / HRB) |
|---|---|---|---|---|---|
| A (Solution Annealed) 1065°C ±15°C, air/oil quench |
895 max / 130 max | 380 max / 55 max | 35 min | — | HRB 85 max |
| TH 1050 760°C + 565°C aging |
1241 min / 180 min | 1034 min / 150 min | 6 min | 15 min | HRC 38 min |
| RH 950 -73°C + 510°C aging |
1586 min / 230 min | 1475 min / 214 min | 6 min | 10 min | HRC 46 min |
Values per AMS 5644 and ASTM A564 for bar products. Condition A provides maximum ductility for machining and forming; TH 1050 and RH 950 deliver progressively higher strength for service applications. SHUNFU METAL’s ISO 9001:2015 certified laboratory validates all mechanical properties on representative samples from each heat treatment batch, with API Q1 ensuring full material traceability throughout the supply chain.