Alloy 625 Stainless Steel Plates

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 plate 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 Weldability and Fabricability: Can be welded with matching filler metals (ERNiCrMo-3). No preheat required for most applications.

International Certifications: Plates 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):

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. 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. 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:
All Alloy 625 plates are solution annealed at 1095–1205°C followed by water quenching. This heat treatment dissolves precipitated carbides and intermetallic phases, relieves internal stresses from rolling, restores optimum corrosion resistance and ductility, and ensures niobium stabilization is effective.

Delivery Condition:
Plates are normally supplied in annealed and pickled condition, providing a clean, smooth surface and excellent corrosion resistance. Pickling removes the oxide scale formed during heat treatment.

Thickness Tolerances (Hot-Rolled – ASTM A480):

Width and Length Tolerances (Hot-Rolled – ASTM A480):

Chemical Analysis: PMI 100% verification 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%).

Dimensional Inspection: Thickness, width, length, flatness, squareness.

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

Ultrasonic Testing (UT): Per ASTM A435 for internal flaw detection (upon request).

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

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

Deepwater Subsea Oil & Gas: Subsea umbilical sheathing plates, umbilical tube bundle protection plates, subsea control module housings, subsea distribution unit components, PLET structural plates (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 plates, firewater system housings.

Subsea Umbilicals: Chemical injection tubing sheathing plates, hydraulic control line protection, MEG injection line components.

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

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

Chemical Processing (Aggressive): High-pressure acid reactor plates, chlor-alkali heat exchanger components, 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 plates, liquefaction facility vessels.

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

Womic Steel offers precision cutting services for Alloy 625 stainless steel plates:

Standard Packaging:

Plates wrapped with moisture-proof paper and VCI film

Edge protectors to prevent damage

Steel skids for plate protection

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

Womic Steel's Shipping Strengths:

Direct cooperation with global shipowners – competitive freight rates

Professional loading and securing teams prevent plate damage

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

Continuous cargo tracking and after-sales follow-up

1. What is the difference between Alloy 625 and Alloy 825 for plate 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 plates be welded?
Yes. Alloy 625 offers excellent weldability with matching filler metal ERNiCrMo-3. No preheat or post-weld heat treatment is required for most applications.

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

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

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

6. Are Alloy 625 plates available with ASME certification?
Yes. Alloy 625 plates can be supplied with ASME SB443 certification for pressure vessel applications.

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

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

High Strength Options: Cold worked condition 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

ASME SB443 Certified: Pressure vessel grade plates available

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

Complete Size Range: Thickness from 3mm to 60mm – standard and custom sizes

Cut-to-Size Services: Plasma, waterjet, and shearing for custom dimensions

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 plates. 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 Plates – No.1 Finish – Subsea Grade):

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