Alloy 625 Stainless Steel Coils

Exceptional Pitting and Crevice Corrosion Resistance: PRE ≥ 45 (typically 45-50) due to high chromium (20-23%), high molybdenum (8-10%), and niobium (3.15-4.15%) content – the highest among nickel alloys for seawater coil applications.

Ultra-High Strength: Yield strength ≥ 415 MPa in annealed condition; cold worked options available for even higher strength requirements (YS up to 860 MPa).

Outstanding Seawater Compatibility: No crevice corrosion or pitting, even in stagnant seawater or high-velocity conditions (up to 20 m/s), significantly outperforming super duplex 2507 in long-term seawater exposure.

Superior Chloride SCC Resistance: High nickel content (≥58%) provides outstanding resistance to chloride-induced SCC and sulfide-induced SSCC.

Excellent High-Temperature Strength and Oxidation Resistance: Maintains excellent mechanical properties up to 980°C (1800°F) with outstanding creep resistance.

Niobium Stabilization – No Sensitization: Niobium addition (3.15-4.15%) stabilizes the alloy against intergranular corrosion, eliminating need for post-weld heat treatment.

NACE MR0175 / ISO 15156 Compliant: Fully qualified for sour service with highest allowable H₂S partial pressures, documented HIC and SSC test reports available.

Broad Temperature Range: Maintains excellent properties from cryogenic (-196°C) to high temperature (980°C), suitable for LNG and thermal oxidizer applications.

Good Formability: Can be cold rolled to precise thicknesses and slit to narrow widths for precision components.

International Certifications: Coils can be certified by ABS, BV, DNV, LR, and comply with NORSOK M-650, NACE MR0175, API 17E, and ISO 13628-5 standards.

Alloy 625 (UNS N06625) is a nickel-chromium-molybdenum alloy with niobium stabilization. The high molybdenum content (8-10%) and niobium (3.15-4.15%) provide exceptional pitting resistance (PRE ≥ 45), the highest among nickel alloys for seawater service. Unlike precipitation-hardenable alloys like Inconel 718, Alloy 625 is solid solution strengthened with niobium stabilization, offering excellent weldability without post-weld heat treatment while maintaining outstanding high-temperature strength.

Comparison of PRE (Pitting Resistance Equivalent) Values:

High-Temperature Tensile Properties (Annealed Condition, Typical Values):

Creep Rupture Strength (Annealed Condition, Typical Values):

NACE MR0175 / ISO 15156 Compliance:
Alloy 625 is fully qualified for sour service applications up to the highest limits specified in NACE MR0175/ISO 15156 for nickel-based alloys. The alloy exhibits exceptional resistance to sulfide stress cracking (SSC) and hydrogen induced cracking (HIC) in H₂S-containing environments. Maximum sour service temperature: 232°C (450°F).

Maximum Recommended Service Temperatures:

Critical Note: Alloy 625 is a solid solution strengthened alloy and does not respond to conventional precipitation hardening like Inconel 718. Cold working is the primary method to increase strength beyond the annealed condition. The alloy must be water quenched after annealing to prevent the precipitation of embrittling phases.

Heat Treatment Condition:
Alloy 625 coils are supplied in one of the following conditions:

Delivery Condition:
Coils are normally supplied in annealed and pickled condition, providing a clean, smooth surface and excellent corrosion resistance. Cold worked coils are available upon request for high-strength applications.

Thickness Tolerances (Cold-Rolled – ASTM A480):

Thickness Tolerances (Hot-Rolled – ASTM A480):

Width Tolerances (Hot-Rolled – ASTM A480):

Flatness Tolerances:

Raw Material Selection: High-quality Alloy 625 (UNS N06625) nickel alloy slabs from certified premium mills (Special Metals, VDM Metals, Haynes International) with certified chemical composition (Ni ≥58%, Cr 20-23%, Mo 8-10%, Nb 3.15-4.15% verification) and traceability. Material is VIM-VAR (Vacuum Induction Melted – Vacuum Arc Remelted) for optimal cleanliness.

Reheating: Slabs heated to forging temperature (1150–1200°C). Temperature control is critical for nickel alloys.

Hot Rolling: Heated slabs passed through roughing and finishing stands to reduce thickness to 3-12mm (hot-rolled coils) with careful reduction rates.

Laminar Cooling: Controlled water cooling to achieve desired microstructure.

Coiling: Hot-rolled strip coiled at approximately 600-700°C for hot-rolled coils.

Solution Annealing: Hot-rolled coils undergo solution annealing at 1095–1205°C to restore corrosion resistance.

Pickling: Removal of oxide scale using specialized pickling acids optimized for high-molybdenum nickel alloys; thorough rinsing required.

Cold Rolling: For thicknesses below 3.0mm, hot-rolled coils further reduced through cold rolling passes.

Cold Rolling Annealing (Optional): Intermediate annealing for cold-rolled coils.

Slitting (Optional): Wide coils cut into narrower strips per customer requirements (20mm to 600mm width).

Inspection & Testing: Dimensional check, PMI, mechanical testing, surface inspection, corrosion testing.

Coiling & Packaging: Coiled to specified ID/OD, wrapped with moisture barrier paper, steel strapped.

Chemical Analysis: PMI 100% verification using handheld XRF spectrometer for Ni (≥58%), Cr (20-23%), Mo (8-10%), Nb (3.15-4.15%).

Intergranular Corrosion Test: ASTM G28 – validates resistance to intergranular corrosion (mandatory).

Pitting Corrosion Test: ASTM G48 – ferric chloride pitting test upon request.

Mechanical Testing: Tensile strength (≥825 MPa), yield strength (≥415 MPa), elongation (≥30%), hardness per ASTM A370.

Dimensional Inspection: Thickness, width, flatness, coil ID/OD using calibrated instruments.

Surface Inspection: Visual check for surface defects, cracks, roll marks, and consistency.

Sour Service Qualification (upon request): HIC per NACE TM0284, SSC per NACE TM0177.

NACE MR0175 Compliance: Full documentation with optional HIC/SSC test reports.

Third-Party Inspection: SGS, BV, DNV, TUV, LR, ABS available upon customer request.

Deepwater Subsea Oil & Gas: Subsea umbilical sheathing, umbilical tube bundles, subsea control module housings, subsea distribution unit components, PLET structural elements (API 17E, ISO 13628-5 compliant, ABS/BV/DNV certified).

Seawater Systems (High Performance): Seawater pump housings, high-pressure seawater injection components, deepwater seawater lift system components, firewater system housings.

Subsea Umbilicals: Chemical injection tubing sheathing, hydraulic control line protection, MEG injection line components, subsea control system housings.

Aerospace & Defense: Aircraft hydraulic system components, fuel system parts, rocket engine propellant line components, missile system structural elements.

Thermal Oxidizers & High-Temperature Ducting: Thermal oxidizer shells, high-temperature process heater housings, incinerator flue gas components, high-temperature ductwork.

Chemical Processing (Aggressive): High-pressure acid reactor shells, chlor-alkali heat exchanger components, vinyl chloride monomer (VCM) processing vessels, mixed acid service equipment.

Offshore Platforms (Critical Service): Topsides HP process piping components, produced water system vessels, chemical injection skid housings (NORSOK M-650 qualified).

LNG & Cryogenic Service: LNG plant components, cryogenic transfer line components, liquefaction facility vessels (maintains toughness down to -196°C).

Power Generation: Supercritical boiler components, high-temperature steam line components, gas turbine fuel system parts.

Womic Steel offers precision slitting services for Alloy 625 coils:

Standard Packaging:

Coils wrapped with moisture-proof paper and VCI (Vapor Corrosion Inhibitor) film

Outer steel strapping (4-8 straps per coil depending on weight)

Wooden pallet or steel skid for coil protection during transport

Plastic edge protectors for slit coils

Clear labeling with grade (Alloy 625/N06625), heat number, dimensions, coil weight, and order number

Womic Steel's Shipping Strengths:

Direct cooperation with global shipowners for competitive freight rates

Professional loading and securing teams using non-metallic slings and padded supports prevent coil damage

Efficient document preparation (EN 10204 Type 3.1 MTR, PMI reports, ASTM G28 test reports, NACE certificates) minimizes customs delays

Rapid delivery time – standard coils maintained in ready stock

Continuous cargo tracking and after-sales follow-up

1. What is the difference between Alloy 625 and Alloy 825 for coil applications?
Alloy 625 has higher molybdenum (8-10% vs 2.5-3.5%), higher PRE (≥45 vs 38-42), higher strength (YS ≥415 MPa vs ≥240 MPa), and significantly better seawater pitting resistance. For deepwater subsea umbilical sheathing and seawater applications, Alloy 625 is the preferred material. For sulfuric/phosphoric acid service, Alloy 825 is more cost-effective.

2. Can Alloy 625 coils be cold rolled to thin gauges?
Yes. Alloy 625 can be cold rolled to thicknesses as low as 0.5mm for precision applications. However, the alloy work hardens rapidly, requiring intermediate annealing passes.

3. Is Alloy 625 resistant to hydrochloric acid (HCl)?
Yes, Alloy 625 has good resistance to dilute HCl and is used in HCl service. For concentrated HCl at elevated temperatures, Hastelloy C276 is recommended.

4. Are Alloy 625 coils suitable for subsea umbilical sheathing?
Yes. Alloy 625 is the industry standard material for subsea umbilical sheathing and tube bundles (API 17E, ISO 13628-5 compliant).

5. What strength levels are available for Alloy 625 coils?
Three conditions: Annealed (YS ≥415 MPa), Cold Worked (YS ≥620 MPa), and Aged/Premium (YS ≥760 MPa). For deepwater subsea components requiring high strength, cold worked condition is recommended.

Outstanding Seawater Resistance: PRE ≥45 – highest among nickel alloys for seawater coil applications

API 17E / ISO 13628-5 Compliant: Suitable for subsea umbilical sheathing – full documentation available

High Strength Options: Cold worked and aged conditions available for high-strength requirements

NACE MR0175 Compliant: Full sour service documentation with HIC/SSC test reports

ASTM G28 Intergranular Tested: Mandatory corrosion resistance verification

Full Traceability: Heat number on each coil – traceable to original mill certificate

Complete Size Range: Thickness from 0.5mm to 12.0mm – standard and custom sizes

Slitting Services: In-house slitting capability for narrow strips (20mm to 600mm)

Wide Temperature Range: Suitable from -196°C to 980°C

Global Delivery: Exported to major deepwater subsea, aerospace, and extreme service projects worldwide

Tel / WhatsApp:

Victor: +86 15575100681

Jack: +86 18390957568

E-mail: info@womicstainless.com

Website: www.womicsteel.com

Contact Womic Steel today for a competitive quote on Alloy 625 stainless steel coils. We offer certified quality, NACE MR0175 compliance, API 17E certification, ASTM G28 corrosion testing, and reliable global delivery for your deepwater subsea and extreme service projects.

Stock Examples (Hot-Rolled Alloy 625 Coils – Annealed – Subsea Grade):

Cold-Rolled Alloy 625 Coils – 2B Finish – Precision Components:

Related Keywords:

Alloy 625 stainless steel coil, Inconel 625 hot rolled coil, UNS N06625 pickled coil, subsea umbilical sheathing coil, NACE MR0175 alloy 625 coil, high strength nickel alloy coil, seawater resistant coil, AP 1250 ksi yield strength coil, ASTM G28 tested coil, cryogenic service alloy 625 coil, LNG plant coil, API 17E compliant coil, ISO 13628-5 coil, NORSOK M-650 qualified coil, thermal oxidizer shell coil, aerospace hydraulic component coil, chemical injection skid coil, deepwater subsea coil, alloy 625 cold rolled coil, 2.4856 stainless steel coil, NW6625 JIS certified coil, alloy 625 coil for seawater pump housing, alloy 625 coil for subsea control module, alloy 625 coil for PLET structure, high temperature alloy coil 980°C, PRE 45 nickel alloy coil.