Inconel 725 (UNS N07725) Supplier – Certified High-Strength NACE Sour Service Bars & Tubes | Shanghai Hangbo Alloy Group

By Shanghai Hangbo Alloy Group Co., Ltd. | ISO 9001:2015 | Est. 2012 | Shanghai, China

Contact: sales@hangboalloy.com | hangbo@nickel-alloy.com | WhatsApp: +86 13611656360

Quick Answer: What Is Inconel 725?

Inconel 725 (UNS N07725) is a precipitation-hardenable nickel-chromium-molybdenum-niobium superalloy that was specifically engineered to provide the corrosion resistance of Inconel 625 with twice the yield strength after age-hardening. It achieves this through the γ" (gamma double prime) precipitation effect while maintaining full compliance with NACE MR0175 / ISO 15156 for sour service (H₂S) environments. Shanghai Hangbo Alloy Group supplies Inconel 725 in precision round bars, seamless tubes, and heavy plates, specializing in the fully aged condition for subsea completion components and high-strength downhole tools.

Key Properties at a Glance

The Downhole Conundrum: Why Weak Parts Bleed Money at 10,000 Feet

Subsea and downhole environments are the ultimate materials test. Salt, H₂S, CO₂, and hydrostatic pressures of 15,000 PSI demand a material that is both chemically inert and mechanically indestructible. Inconel 725 exists to solve this exact paradox.

Pain Point 1: The "625 Replacement" Failure

Many distributors try to sell standard Inconel 625 bars for high-strength oilfield components (hangers, landing nipples). While 625 has legendary corrosion resistance, its annealed yield strength is only 414 MPa. In a deep-water high-pressure environment, a 625 hanger can yield (stretch) slightly, causing a critical seal failure. Inconel 725 solves this with a yield strength of 827 MPa+ — literally double.

Pain Point 2: The NACE Hardness Ceiling Violation

For use in sour gas (H₂S), NACE MR0175 imposes a strict maximum hardness of 40 HRC. If a heat-treater rushes the aging process or doesn't homogenize the material properly, local hard spots can exceed 42 HRC. If an inspector tests these spots, the entire batch is rejected. Shanghai Hangbo guarantees uniform hardness ≤ 40 HRC through multi-point cross-sectional testing, certified on every MTC.

Pain Point 3: The "Mystery Heats" Delaying Your Inspection

Because Inconel 725 is used in safety-critical API 6A wellhead components, the paperwork must be perfect. We frequently see orders delayed because the "3.1 MTC" provided by a trader had no link to the actual melt heat number. Hangbo provides full Heat-Number-to-Product traceability, including the triple-melt (VIM+ESR+VAR) logs, so your third-party inspector can sign off in hours, not weeks.

How Shanghai Hangbo Alloy Group Solves Downhole Strength Issues

Product Overview: The Sour-Service Strategist

Inconel 725 (UNS N07725) is the ultimate answer for mechanical engineers screaming for "More Strength" without compromising "Chemical Immunity." While it shares the Ni-Cr-Mo base of Alloy 625, the addition of higher niobium and titanium turns this material from a soft solid-solution alloy into a hardened engineering solid.

Why specify 725 from Shanghai Hangbo?

• API 6A Ready: We supply 725 bars with the specific chemistry, documentation, and heat-treatment logs required for API 6A monogrammed valve bodies and wellhead components.
• Impact Toughness: Despite its high strength, our aged 725 achieves Charpy V-notch > 40 Joules at -60°C, ensuring no brittle propagation in deep-sea temperatures.
• Salt-Water Immunity: With a PREN > 40, it effectively eliminates the risk of crevice corrosion in stagnant seawater completions.

Founded in 2012, Shanghai Hangbo Alloy Group has become the oilfield's trusted partner for 725. With clients in 32 countries, our material is working thousands of feet beneath the sea right now.

Executive Standards

Chemical Composition (wt.% per ASTM B805)

100% OES verified on every heat at Shanghai Hangbo Alloy Group.

Critical Note: The niobium (2.75-4.0%) and carbon (≤0.03%) balance is what makes the γ" precipitates possible. This is fundamentally different from standard Alloy 625 (which is Nb 3.15-4.15% but C ≤0.10%).

Mechanical & Physical Properties

Fully Heat-Treated (Age-Hardened) Properties

Heat Treatment: The "Double-Age" Formula

To achieve API/NACE properties, 725 must undergo a specific two-step age hardening, not a generic solution treatment.

• Solution Anneal: 1020°C – 1075°C for 1-2 hours. This dissolves all precipitates and resets the grain structure.
• Age Step 1: 730°C for 8 hours. This nucleates the γ" phase sites.
• Age Step 2: 620°C for 8 hours. This is the final "precipitation" step that locks the γ" into the matrix, achieving hardness.
• Cooling: Air cool between steps.
• Shanghai Hangbo protocol: We strictly monitor the furnace cooling rate to ensure a maximum Hardness of 39 HRC, deliberately leaving a 1HRC safety margin versus the NACE 40 limit.

Industry Applications — Proven Performance

Quality Assurance: The 7-Stage Protocol for API Compliance

1. Triple-Melt Refining: Confirmation of VIM+ESR+VAR sequential melt logs.
2. OES Verification: Confirming the exact Nb/Mo ratio for age-hardening response.
3. Full-Body UT: 100% ultrasonic test per ASTM A388 on all bars.
4. Multi-Point Hardness: Cross-sectional Rockwell mapping to prove NACE compliance (≤40 HRC).
5. Charpy V-Notch: Impact test verification at -60°C for subsea safety cases.
6. Macro-Etch: Visual confirmation of grain flow and structural uniformity in forgings.
7. Heat-Number Etching: Permanent traceability linking the bar back to the VIM ingot and API 6A documentation.

Frequently Asked Questions (FAQ)

Q1: What is Inconel 725 used for?

It is primarily used for high-strength, corrosion-resistant components in the oil and gas industry, specifically subsea wellhead hangers, landing nipples, and API 6A pressure-containing components.

Q2: What is the density of Inconel 725?

8.31 g/cm³ (0.300 lb/in³).

Q3: How does Inconel 725 compare to Inconel 625?

Inconel 725 is the age-hardenable upgrade. After heat treatment, it reaches roughly 2x the yield strength of standard annealed Inconel 625, while maintaining equivalent corrosion resistance.

Q4: Is Inconel 725 NACE compliant?

Yes. When produced in the correct age-hardened condition with uniform hardness ≤ 40 HRC, it fully complies with NACE MR0175 / ISO 15156 for sour service.

Q5: What is the maximum service temperature for strength?

Structural strength is maintained up to approximately 675°C (1250°F). Above this, the gamma-double-prime precipitates begin to coarsen.

Q6: What is the tensile strength of Inconel 725?

In the fully aged condition, the minimum tensile strength is ≥ 1034 MPa (150 ksi).

Q7: What is the yield strength of Inconel 725?

The 0.2% offset yield strength in the fully aged condition is ≥ 827 MPa (120 ksi).

Q8: What is the elongation of Inconel 725?

In the fully aged condition, the minimum elongation is ≥ 20%.

Q9: What heat treatment does Inconel 725 require?

It requires solution annealing followed by a two-step age hardening: ~730°C for 8 hours and then ~620°C for 8 hours.

Q10: Is Inconel 725 weldable?

Yes, but it requires strict process control. We recommend welding in the annealed condition using matching 725 filler (ERNiCrMo-14) followed by full post-weld heat treatment.

Q11: What forms do you supply?

Round bars (10mm-400mm), forgings, seamless tubes, and plates.

Q12: What is the price of Inconel 725 per kg?

Expect a range of $36–$85 USD/kg depending on form and size. Contact sales@hangboalloy.com for a real-time quote.

Q13: Does Shanghai Hangbo ship internationally?

Yes. We export to 32 countries with DDP terms and full logistical support.

Contact Shanghai Hangbo Alloy Group

Get a competitive quote within 10 minutes.

Shanghai Hangbo Alloy Group Co., Ltd. — Your Specialized Partner for High-Strength Sour-Service Solutions.