Inconel 625 (UNS N06625): Round Bars, Seamless Tubes & Plates — Technical Data Sheet

Quick Answer: What Is Inconel 625?

Inconel 625 (UNS N06625 / W.Nr. 2.4856 / GH3625) is a premier austenitic nickel-based superalloy formulated for service environments demanding high mechanical strength and exceptional corrosion resistance. Its high performance stems from the solid-solution strengthening effects of molybdenum (8–10%) and niobium (3.15–4.15%) within its stable nickel-chromium matrix. This eliminates the necessity for precipitation-hardening heat treatments. Operating efficiently from cryogenic limits up to an oxidation threshold of 1800°F (982°C), Inconel 625 is widely utilized in aerospace propulsion, marine engineering, and severe chemical processing environments.

Product Overview

At the atomic level, its face-centered cubic (FCC) crystal lattice guarantees superb ductility and impact toughness across all temperature regimes. Its primary advantage is solid-solution strengthening, where large molybdenum and niobium atoms distort the nickel matrix to effectively restrict dislocation movement, which yields elevated fatigue strength and superb resistance to chloride-ion stress-corrosion cracking, pitting, and crevice degradation without age-hardening brittleness.

Shanghai Hangbo Alloy Group Co., Ltd., established in 2012, stands as a top-tier global manufacturer and supplier of Inconel 625. Operating under a certified ISO 9001:2015 quality management system, we command an export network covering 50+ countries. Our portfolio contains high-precision centerless ground round bars, heavy industrial plates, and high-pressure seamless tubing engineered for critical industrial applications. By managing carbon distribution and grain refinement during melting and forging, we ensure our material provides robust structural performance under severe stress. Every order comes with 100% material traceability and certified documentation, ensuring compliance with strict global engineering standards.

Executive Standards

Shanghai Hangbo Alloy Group Co., Ltd. manufactures Inconel 625 in strict compliance with international technical specifications:

Note: Shanghai Hangbo executes 100% confirmation of chemical compliance using Optical Emission Spectroscopy (OES) for every melt lot.

Chemical Composition

The corrosion-resistant profile of Inconel 625 depends on its exact chemical balance. Chromium ensures high-temperature oxidation resistance, while molybdenum safeguards against localized pitting in chloride environments.

Mechanical Properties

Inconel 625 delivers excellent design allowable stresses. The data below outlines typical properties for annealed stock.

Room-Temperature Mechanical Properties

High-Temperature Performance: Strength Retention Analysis

Inconel 625 retains remarkable mechanical properties under thermal stress, establishing its credentials as a critical superalloy:

How Inconel 625 Is Produced

Round Bar & Forging

• 1. Double Melting (VIM + ESR): primary Vacuum Induction Melting (VIM) for degassing, followed by Electroslag Remelting (ESR) to remove inclusions and achieve chemical uniformity.
• 2. Multi-Directional Forging: ingots are preheated and hot-forged via hydraulic presses; heavy deformation refines grain morphology to ASTM Size 5 or finer.
• 3. Solution Annealing: products undergo rapid water quenching after heating to freeze the single-phase solid-solution structure.
• 4. Precision Grinding: bars are centerless-ground to h8/h9 tolerances, guaranteeing surface roughness (Ra) under 0.8 μm.

Seamless Tube & Pipe

• 1. Billet Piercing: solid forged rounds are hot-pierced and extruded into heavy-walled hollow mother tubes.
• 2. Cold Pilgering: precision multi-pass cold-pilgering reductions establish uniform wall thickness and excellent concentricity.
• 3. Hydrogen Bright Annealing: tubes undergo heat treatment in a dry hydrogen atmosphere, producing an oxide-free bright finish.
• 4. Defect Testing: every batch undergoes 100% Eddy Current (ET) and hydrostatic testing to rule out sub-surface defects.

Sheet, Plate & Strip

• 1. Hot Rolling: slabs are processed on four-high reversing mills to reduce thickness while avoiding carbide aggregation.
• 2. Cold Rolling: precise gauge control maintains thickness tolerances within ±0.05 mm.
• 3. Leveling Operations: tension leveling maximizes flatness for laser and waterjet profiling compatibility.
• 4. Passivation Chemical Pickling: finished plates are immersed in a nitric-hydrofluoric bath to eliminate scale and restore the passive surface.

Industry Applications: Solving Engineering Challenges

Aerospace and Defense

Inconel 625 is standard for jet engine ducting, fuel lines, and turbine shroud rings. Its fatigue properties resist micro-cracking caused by cyclic thermal changes and intense vibration. It is also used in submarine components owing to its non-magnetic properties.

Marine and Subsea Engineering

Marine infrastructures encounter aggressive chloride exposures. Inconel 625 supplies protection for subsea valves, propeller blades, and wire rope. It is immune to pitting and crevice corrosion in stagnant ocean water where conventional stainless steels pit rapidly.

Chemical Processing Plants

The alloy's resilience against phosphoric, nitric, and sulfuric acids makes it essential for chemical reactors, heat exchangers, and distillation units. Its specialized resistance to intergranular corrosion guarantees that structural weld joints remain intact under high-pressure chemical transfer.

Power and Nuclear Engineering

In nuclear infrastructures, Inconel 625 serves in reactor control components because of its low neutron swelling and high mechanical stability under radiation. For renewable energy, it handles corrosive molten salts in concentrated solar power (CSP) receivers and geothermal wells.

Quality Assurance: 7-Stage Zero-Defect Inspection Protocol

Shanghai Hangbo Alloy Group Co., Ltd. deploys an intensive inspection matrix to support a zero-defect mandate across all production lines:

• 1. Chemical verification: OES analysis on every melt batch alongside handheld PMI validation on finished products ensures composition parameters match executive limits.
• 2. Ultrasonic Testing (UT): Performed per ASTM A388 standards across all bars and plates to confirm the absence of inner voids, seams, or gas inclusions.
• 3. Eddy Current Testing (ET): Applied 100% to tubes following ASTM E309 protocols to check surface and sub-surface continuity.
• 4. Hydrostatic Pressure Verification: Tubes undergo hydrostatic tests up to 10,000 PSI to verify wall integrity under high-pressure parameters.
• 5. Mechanical Destructive Testing: Tensile, offset yield, elongation, and Brinell hardness examinations are executed per heat lot to verify strength criteria.
• 6. Dimensional Metrology Check: Digital calipers and computerized laser sensors measure geometry, guaranteeing all diameter, wall, and length tolerances match orders.
• 7. Visual and Microstructure Audit: Surface quality checks are paired with metallographic microscope tests to evaluate grain size (ASTM E112) and phase homogeneity.

All items leave our facilities accompanied by ISO 9001:2015 certification and EN 10204 3.1 Mill Test Certificates. Third-party inspection options through SGS, TUV, or Bureau Veritas (BV) are organized upon customer request.

Frequently asked questions