Alloy 825 Stainless Steel Coils

Superior Sulfuric and Phosphoric Acid Resistance: Outstanding performance in H₂SO₄ (all concentrations up to moderate temperature), H₃PO₄, and mixed acids, making Alloy 825 the premier coil material for fertilizer and chemical processing facilities.

NACE MR0175 / ISO 15156 Compliant: Fully qualified for sour service (H₂S) up to 232°C (450°F), with documented HIC and SSC test reports available for oil and gas applications.

Excellent Chloride Stress Corrosion Cracking Resistance: High nickel content (38-46%) provides outstanding resistance to chloride-induced SCC, outperforming all austenitic and duplex stainless steel grades.

Good Pitting and Crevice Corrosion Resistance: Molybdenum (2.5-3.5%) and chromium (19.5-23.5%) provide enhanced resistance to localized corrosion in chloride-containing environments.

Titanium Stabilization: Titanium addition (0.6-1.2%) stabilizes the alloy against intergranular corrosion after welding or high-temperature exposure, eliminating the need for post-weld heat treatment.

Good Weldability: Nickel-iron-chromium alloy offers good weldability with matching filler metals (ERNiCrMo-3 or ERNiCrMo-10). No preheat required for most applications.

Excellent Resistance to Reducing and Oxidizing Acids: Performs well in both reducing acids (sulfuric, hydrochloric, phosphoric) and oxidizing acids (nitric, chromic), as well as mixed acid environments.

Good High-Temperature Strength: Maintains excellent mechanical properties up to 540°C (1000°F) in non-oxidizing environments.

International Certifications: Coils can be certified by ABS, BV, DNV, LR, and comply with NORSOK M-650, NACE MR0175, and ASME standards.

Alloy 825 is a nickel-iron-chromium alloy with controlled additions of molybdenum and copper for enhanced corrosion resistance in reducing acid environments. The copper content (1.5-3.0%) provides exceptional resistance to sulfuric acid, while molybdenum (2.5-3.5%) enhances pitting resistance. Titanium stabilization (0.6-1.2%) prevents sensitization and intergranular corrosion after welding, making Alloy 825 suitable for welded fabrications without post-weld heat treatment.

Comparison of PRE (Pitting Resistance Equivalent) Values:

High-Temperature Tensile Properties (Typical Values):

Maximum Recommended Service Temperatures:

Critical Note: Alloy 825 is titanium-stabilized, which prevents sensitization and intergranular corrosion after welding. Unlike many stainless steels, Alloy 825 can be used in the as-welded condition without post-weld heat treatment for most corrosive environments. This is a significant advantage for field fabrication and repair of welded coil fabrications.

Heat Treatment Condition:
All Alloy 825 coils are solution annealed at 925–1040°C followed by rapid cooling (water quenching or rapid air cooling). This heat treatment dissolves precipitated carbides and intermetallic phases, relieves internal stresses from rolling, restores optimum corrosion resistance and ductility, and ensures titanium stabilization is effective.

Delivery Condition:
Coils 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 and restores the passive surface.

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 825 (UNS N08825) nickel-iron-chromium slabs from certified premium mills (Special Metals, VDM Metals, Carpenter) with certified chemical composition (Ni 38-46%, Cr 19.5-23.5%, Mo 2.5-3.5%, Cu 1.5-3.0%, Ti 0.6-1.2% verification) and traceability.

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).

Laminar Cooling: Controlled water cooling to achieve desired microstructure and mechanical properties.

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

Solution Annealing: Hot-rolled coils undergo solution annealing at 925–1040°C to restore corrosion resistance.

Pickling: Removal of oxide scale using specialized pickling acids optimized for 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.

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 (38-46%), Cr (19.5-23.5%), Mo (2.5-3.5%), Cu (1.5-3.0%), Ti (0.6-1.2%).

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

Mechanical Testing: Tensile strength (≥585 MPa), yield strength (≥240 MPa), elongation (≥30%), hardness (≤200 HBW) 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.

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

Sulfuric Acid Plants: Acid storage tank shells, heat exchanger shells, acid cooler components, piping systems, tank farm vessels (NACE MR0175 limited).

Phosphoric Acid Production: Evaporator shells, heat exchanger components, reaction vessel shells, fertilizer storage tanks, DAP/MAP production equipment.

Pickling Plants (Stainless Steel): Pickling tank shells, acid recovery system vessels, rinse tank components, steel mill pickling line equipment, titanium dioxide production vessels.

Oil & Gas Sour Service: Amine unit tanks, sour water stripper vessels, glycol regeneration tanks, produced water treatment vessels (NACE MR0175 compliant).

Offshore Chemical Injection: Methanol injection tank shells, glycol unit vessels, chemical storage tank components (ABS/BV/DNV/LR certified).

Chemical Processing (Aggressive): Reactor vessels, distillation column shells, agitator tanks, catalyst handling vessels, organic acid processing equipment (acetic, formic, citric).

Pharmaceutical (High-Purity): Cleanroom equipment shells, sterile process vessels, WFI storage tanks, bioreactor shells, pharmaceutical process equipment.

Fertilizer Production: DAP/MAP production vessels, granulator shells, conveyor components, storage silos.

Hydrometallurgy: Solvent extraction vessel shells, electrowinning cell components, pregnant leach solution tanks, nickel/cobalt processing equipment.

Heat Exchangers: Shell and tube heat exchanger shells, tube sheets, channel covers, baffles (non-corrosive side only).

Womic Steel offers precision slitting services for Alloy 825 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 825/N08825), 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 prevent coil damage during transit

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

Rapid delivery time – standard coils maintained in ready stock

Continuous cargo tracking and after-sales follow-up

1. How does Alloy 825 compare to 316L for coil applications in acid service?
Alloy 825 offers significantly better resistance to sulfuric acid (H₂SO₄), phosphoric acid (H₃PO₄), and sour gas (H₂S). For acid plant vessels and chemical processing equipment where 316L would corrode rapidly, Alloy 825 is required.

2. Is Alloy 825 resistant to hydrochloric acid (HCl)?
Limited. Alloy 825 has fair resistance to dilute HCl but is not recommended for concentrated or aerated HCl. For hydrochloric acid service, consider Hastelloy C276 coils.

3. Can Alloy 825 coils be welded without post-weld heat treatment?
Yes. Titanium stabilization prevents sensitization, and PWHT is not required for most corrosive environments. This is a significant advantage for field fabrication.

4. Are Alloy 825 coils suitable for sour service (H₂S)?
Yes, with proper hardness control. Alloy 825 can be NACE MR0175 / ISO 15156 compliant for sour service. Full documentation including HIC/SSC test reports available upon request.

5. What is the maximum service temperature for Alloy 825 coils?
400°C (752°F) for general corrosive service. For sulfuric acid service specifically, limit to 150°C (302°F) depending on acid concentration.

Premier Acid Service Material: Excellent resistance to H₂SO₄, H₃PO₄, and sour gas – ideal for chemical processing and fertilizer production

NACE MR0175 / ISO 15156 Compliant: Full documentation for sour service applications

Titanium Stabilized: ASTM G28 intergranular corrosion tested – no PWHT required

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

Complete Size Range: Thickness from 1.0mm to 12.0mm – standard and custom sizes

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

Global Delivery: Exported to major chemical plants, acid facilities, and offshore 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 825 stainless steel coils. We offer certified quality, NACE MR0175 compliance, ASTM G28 corrosion testing, and reliable global delivery for your acid service and chemical processing projects.

Stock Examples (Hot-Rolled Alloy 825 Coils – Annealed & Pickled – Acid Service Grade):

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