Introduction

Inconel 625 Alloy (UNS N06625) is a nickel-chromium-molybdenum-columbium (niobium) alloy that delivers exceptional strength without age-hardening treatments, due to the solid solution effects of molybdenum and columbium. This high strength Inconel 625 contains a minimum of 58% nickel, 20–23% chromium, 8–10% molybdenum, and 3.15–4.15% niobium, providing corrosion resistant Inconel 625 performance across an exceptionally wide range of severely corrosive environments—with particular resistance to pitting, crevice corrosion, and chloride-ion stress-corrosion cracking. The alloy maintains high strength from cryogenic temperatures up to 1800°F (980°C) and offers good oxidation resistance, making it the preferred material for aerospace, oil and gas, chemical processing, marine engineering, offshore equipment, heat exchangers, power generation, and nuclear industry applications. Available in Inconel 625 plate, sheet, seamless pipe, tube, bar, round bar, wire, fittings, flanges, and forgings, in hot rolled, cold rolled, cold drawn, annealed, and solution annealed conditions.

Chemical components 

Mechanical properties

Physical properties

Inconel 625 Available Products and Standard

1. GB/T 15007 (Nickel and Nickel Alloy Plate, Strip, and Foil)

Domestic Grade: NS3306 (GB/T 15007) / Inconel 625 equivalent

Type: Sheet / Plate / Strip / Wire / Tube / Bar

Size Range:

• Inconel 625 Wire: 0.1 – 15.0 mm dia

• Inconel 625 Strip: 0.05 – 5.0 mm thick × 5 – 500 mm wide

• Inconel 625 Round Bar: 8 – 355 mm dia

• Inconel 625 Sheet / Plate: 0.5 – 180 mm thick

• Inconel 625 Seamless Tube / Pipe: Custom sizes available

Surface: Annealed, Bright, Pickled, Ground

Testing: Chemical analysis, mechanical test (tensile strength, yield strength, elongation), hardness test, intergranular corrosion test, dimensional inspection

2. ASTM B443 (Standard Specification for Nickel-Chromium-Molybdenum Alloy Plate, Sheet, and Strip)

Grade: UNS N06625 / Inconel 625 / Alloy 625

Type: Sheet / Plate / Strip

Size Range:

• Inconel 625 Sheet / Plate: 0.5 – 180 mm thick (hot rolled or cold rolled)

• Inconel 625 Strip: 0.05 – 5.0 mm thick × up to 500 mm wide (coils)

Surface: Annealed, Pickled, Bright, Polished

Testing: Chemical analysis, mechanical test (tensile, yield, elongation), hardness test, intergranular corrosion test, pitting corrosion test, dimensional inspection

3. ASTM B444 (Standard Specification for Nickel-Chromium-Molybdenum Alloy Seamless Pipe and Tube)

Grade: UNS N06625 / Inconel 625 / Alloy 625

Type: Seamless Pipe / Seamless Tube

Size Range:

• Inconel 625 Seamless Pipe: 6 – 610 mm OD × 1 – 50 mm wall thickness

• Inconel 625 Seamless Tube: Custom sizes

Surface: Annealed, Pickled, Bright

Testing: Chemical analysis, mechanical test (tensile, yield, elongation), hydrostatic test, eddy current test, dimensional inspection

4. ASTM B446 (Standard Specification for Nickel-Chromium-Molybdenum Alloy Rod and Bar)

Grade: UNS N06625 / Inconel 625 / Alloy 625

Type: Round Bar / Rod / Wire

Size Range:

• Inconel 625 Round Bar: 8 – 355 mm dia (hot rolled or cold drawn)

• Inconel 625 Wire: 0.1 – 15.0 mm dia (coils or straight)

Surface: Annealed, Pickled, Ground, Turned, Bright

Testing: Chemical analysis, mechanical test (tensile, yield, elongation), hardness test, ultrasonic test, dimensional inspection

Applications

1. Aerospace & Aircraft Engine

• For aircraft engine components, exhaust systems, and turbine shrouds, Inconel 625 for aerospace delivers high strength at temperatures up to 980°C (1800°F) with excellent oxidation resistance. Its ability to withstand high stress and a wide range of temperatures makes it a fitting choice for critical flight components.

• For aircraft ducting systems, gas turbine engine components, and combustion chamber parts, Alloy 625 seamless pipe and UNS N06625 tube provide reliable performance under extreme thermal and mechanical loads.

2. Oil & Gas / Offshore Equipment

• For sour gas service (H₂S/CO₂ environments), Inconel 625 for oil and gas is specified for downhole tools, wellhead equipment, and subsea pipelines. The alloy is NACE MR0175 certified for sour service applications, resisting sulfide stress corrosion cracking and chloride pitting.

• For offshore platforms, subsea manifolds, and subsea production systems, Inconel 625 for offshore equipment withstands seawater corrosion, chloride attack, and the corrosive effects of produced fluids.

3. Marine Engineering & Seawater Systems

• For marine engineering applications including seawater cooling systems and propeller shafts, Inconel 625 for marine engineering resists pitting and crevice corrosion in warm, high‑chloride environments. This seawater resistant Inconel 625 is immune to chloride-ion stress-corrosion cracking.

• For seawater applications and ocean-going equipment, Inconel 625 alloy eliminates pitting and crevice attack—a critical advantage over stainless steels in marine service.

4. Chemical Processing & Heat Exchangers

• For reactors, distillation columns, and heat exchangers handling sulfuric acid, hydrochloric acid, nitric acid, and mixed acid streams, Inconel 625 for chemical processing provides broad resistance to both reducing and oxidizing environments. Its critical pitting temperature (CPT) in 3.5% NaCl solution reaches 85°C, far exceeding stainless steel performance.

• For heat exchangers, condenser tubing, and reboiler bundles in aggressive chemical service, Inconel 625 tube combines high strength with outstanding resistance to localized attack.

5. Power Generation & Nuclear Industry

• For power generation equipment including gas turbine components and industrial furnaces, Inconel 625 alloy retains mechanical strength at elevated temperatures with excellent oxidation resistance.

• For nuclear industry applications including reactor components and nuclear water reactors, UNS N06625 seamless pipe provides the corrosion resistance and radiation stability required for demanding nuclear environments.

6. Pollution Control & Industrial Equipment

• For flue gas desulfurization scrubbers, stack-gas reheaters, and pollution control equipment, Alloy 625 plate withstands low‑pH, high‑chloride environments with excellent resistance to pitting and crevice corrosion.

• For bubble caps, transfer piping, valves, reaction vessels, and distillation columns, Inconel 625 fittings and flanges provide reliable service across diverse industrial applications.

FAQ – Inconel 625 Alloy

Q: What is the difference between Inconel 625 and Hastelloy C276?

A: Inconel 625 alloy is better suited for oxidizing environments, while Hastelloy C276 excels in reducing environments. Inconel 625 generally has higher tensile and yield strength, particularly at elevated temperatures, whereas C276 offers superior resistance to wet chlorine and strong oxidizing chemicals. The choice depends on the nature of the corrosive environment—Inconel 625 for high strength and oxidation resistance; C276 for extreme chemical corrosion resistance.

Q: Can Inconel 625 be welded without post‑weld heat treatment?

A: Yes. Inconel 625 seamless pipe can be welded using TIG, MIG, SMAW, and other standard processes. Known as the "most weldable high‑strength nickel alloy," it typically requires no preheat or post‑weld heat treatment. For thicker sections or highly constrained structures, post‑weld heat treatment at 925°C (1700°F) followed by air cooling may be recommended.

Q: What is the maximum operating temperature for Inconel 625?

A: Inconel 625 alloy operates effectively from cryogenic temperatures down to -196°C (-320°F) up to 980°C (1800°F) in continuous service. It can withstand short‑term exposure up to 1200°C (2190°F). For long‑term service above 650°C, precipitation of γ″ (Ni₃Nb) and other phases should be considered.

Q: What industries commonly use Inconel 625?

A: Aerospace (aircraft engines, exhaust systems, gas turbine components), oil and gas (downhole tools, subsea pipelines, sour gas service), marine engineering (seawater systems, propeller shafts, offshore platforms), chemical processing (reactors, heat exchangers, acid handling), power generation (gas turbines, industrial furnaces), nuclear industry (reactor components), and pollution control (FGD scrubbers, waste treatment). This high strength Inconel 625 is the material of choice where failure is not an option.

MONO Group specializes in the supply of Inconel Alloy 625 and a comprehensive portfolio of nickel‑chromium‑based superalloys for aerospace, marine, chemical, and nuclear applications. As a China‑based manufacturer and wholesale distributor, we offer plates, sheets, round bars, seamless tubes, welded pipes, fittings, flanges, and custom‑machined parts – all produced in accordance with ASTM, ASME, DIN, ISO, and GB specifications. We also provide cut‑to‑size, precision machining, and surface finishing services to meet your project requirements. For detailed technical datasheets, stock availability, or a competitive quotation, please contact us at info@monokj.com – our team is ready to assist with fast, expert responses.