Project Description
Overview of P650 Non-Magnetic Steel
P650 non-magnetic steel is a high-performance, austenitic alloy engineered specifically for the extreme demands of directional drilling and downhole measurement environments. Belonging to the specialized Mn-Cr-Mo-N alloy family, this grade achieves an exceptional balance of mechanical strength and ultra-low magnetic permeability. Magnetic interference from standard drill string components can cause trajectory deviations, leading to costly wellbore placement errors. Through a proprietary cold-working process, P650 delivers high yield and tensile strength across its full length while maintaining a relative permeability of ≤ 1.005. This ensures zero interference with MWD sensors, allowing the magnetic compass to accurately read the Earth's magnetic field without distortion.
Furthermore, its enriched chromium, molybdenum, and nitrogen content provides robust pitting corrosion resistance, mitigating premature failure in aggressive, chloride-rich wellbore fluids. Downhole environments often contain high concentrations of chlorides, which can initiate pitting in standard stainless steels. The addition of molybdenum and nitrogen in this alloy dramatically improves the pitting resistance equivalent number (PREN), making it highly resilient against localized corrosive attacks. As a specialized manufacturer of high-performance steel for the oil and gas sector, Hunan ShunFu Metal Material Co., Ltd. produces P650 solid bars and non-magnetic hollow bars to the strictest industry tolerances. You can explore our complete range of non-magnetic steel products to find the right fit for your drilling requirements.
Key Applications in Downhole Operations
In oil and gas extraction, sourcing P650 non-magnetic steel for directional drilling stabilizers, subs, and HWDP is critical, as these components must remain magnetically transparent. Non-magnetic drill collars (NMDC) placed at the bottom of the drill string provide weight on the bit while remaining invisible to MWD sensors. MWD and LWD tools require protective housings that shield sensitive electronics from extreme downhole pressures and temperatures. If you are sourcing specific downhole components, our specialized drill collar solutions provide comprehensive compatibility with these applications.
In mining and drilling engineering, this austenitic steel is utilized for rock drill steel components requiring non-magnetic properties, downhole instrumentation protective sleeves, and exploration drilling tools. For broader structural needs, you can review our hollow bar product category for compatible dimensions.
Specifications and Industry Standards
P650 operates primarily as a proprietary performance-driven specification rather than a universally cataloged ASTM/ASME material grade. It conforms to critical industry frameworks and testing protocols to ensure field reliability. API Spec 7-1 and API Spec 8 dictate the performance requirements for drill collars and non-magnetic drilling equipment, ensuring geometrical tolerances and magnetic properties are consistent. ASTM A262 Practices A and E provide the standard for verifying intergranular corrosion resistance, mandated for sensitization testing to ensure the material has not undergone detrimental carbide precipitation during manufacturing. ASTM E114 governs the ultrasonic inspection standard, utilized for 100% volumetric testing of our products, detecting hidden discontinuities that could lead to fatigue failure. Available product shapes include Solid Round Bars, Hollow Bars (Tubulars), and Drill Collars.
Chemical Composition and Mechanical Properties
Chemical Composition
The high manganese content (19.50-20.50%) stabilizes the austenitic structure at room temperature, replacing the need for high nickel content found in other non-magnetic alloys, resulting in a more cost-effective yet high-performing solution. Chromium provides baseline corrosion resistance, while molybdenum and nitrogen enhance localized corrosion resistance.
| Element | Specification (%) |
|---|---|
| C | max. 0.06 |
| Mn | 19.50 - 20.50 |
| Cr | 18.00 - 19.00 |
| Mo | 1.70 - 2.00 |
| N | 0.55 - 0.65 |
| Ni | 3.00 - 4.50 |
Mechanical Properties
Achieving 140 ksi yield strength in smaller ODs (up to 9 1/4") and 130 ksi in larger ODs (9 1/2" and above) through cold-working ensures that collars do not bend or buckle under extreme compressive and torsional loads downhole. The 20% elongation and 50% reduction of area guarantee that the steel retains sufficient ductility to avoid brittle catastrophic failure.
| Property | OD up to 9 1/4" | OD 9 1/2" and larger |
|---|---|---|
| Yield Strength (min., 0.2% offset) | 965 N/mm² (140 ksi) | 900 N/mm² (130 ksi) |
| Tensile Strength (min.) | 1035 N/mm² (150 ksi) | 1035 N/mm² (150 ksi) |
| Elongation (min.) | 20% | 20% |
| Reduction of Area (min.) | 50% | 50% |
| Impact Energy (min.) | 82 J (60 ft.lb) | 82 J (60 ft.lb) |
| Endurance Strength (min., N=10⁵) | 414 N/mm² (60 ksi) | 414 N/mm² (60 ksi) |
| Hardness (Brinell) | 330 - 430 HB | 330 - 430 HB |
Melting Routes and Heat Treatment
ShunFu Metal offers flexible melting routes for P650 non-magnetic steel to match specific operational demands. The standard route is EAF + LF + VD, which removes dissolved gases like hydrogen and oxygen to prevent hydrogen-induced cracking. For elevated purity and homogeneity, we provide ESR or PESR options, reducing non-metallic inclusions. For the most rigorous downhole applications, the VIM + VAR route represents the pinnacle of steel cleanliness. Given its high chromium and nitrogen content, an AOD step is integrated into the refining process for optimal corrosion resistance and precise nitrogen introduction. To understand our manufacturing pedigree, you can learn more about our company.
The heat treatment process for P650 non-magnetic steel involves two primary phases. Warm forging and rapid quenching prevent material sensitization and intergranular stress corrosion cracking by avoiding chromium carbide formation at grain boundaries. Subsequently, a special cold-working phase applies full-length ambient cold working (strain hardening). This step is critical to achieve the minimum yield strength and target hardness throughout the entire cross-section.
Surface Finish, Machining, and Quality Assurance
To maximize the performance and longevity of P650 non-magnetic steel, ShunFu Metal provides comprehensive surface treatments and precision machining. We offer turning, grinding, and milling for initial shaping, followed by CNC precision machining for tight dimensional tolerances, ensuring that drill collar threads and shoulders mate perfectly. For deep-hole requirements, BTA boring and long-distance gunhole drilling deliver exceptional internal surface finishes, crucial for the accurate placement of MWD electronics.
Crucially, to prevent transgranular SCC, we apply specialized surface enhancements including hammer peening, roller burnishing, and shot peening. These induce beneficial compressive residual stresses on the component surface, effectively counteracting operational tensile stresses and significantly extending the fatigue life of the material.
Our quality control spans pre-production, in-process, and post-production stages. 100% volumetric ultrasonic inspection is executed per ASTM E114. Magnetic permeability is certified for every collar via a proprietary probe-testing process, ensuring values remain ≤ 1.005. Intergranular corrosion resistance is strictly verified per ASTM A262. ShunFu Metal issues EN 10204 3.1 certificates standardly, with 3.2 certificates available upon request. Third-party inspections by SGS or TÜV can be seamlessly arranged.
Available Sizes, Delivery, and Packing
ShunFu Metal supplies P650 non-magnetic steel across a broad dimensional spectrum, demonstrating robust manufacturing flexibility. We offer hot-rolled and forged round bars, flat bars, and non-magnetic hollow bars tailored for downhole applications.
- Ready Stock: Common sizes available; single-piece orders accepted; ~7 days delivery.
- Custom Forged/Rolled: MOQ typically 3 tons; ~30 days lead time.
- Small Batch Special Grades: Custom melts start from 3-5 tons using our small induction furnaces.
- Large Batch Orders: 30-60 tons via EAF, ensuring rapid and scalable delivery.
For shipping, black skin products are securely fastened with steel wire strapping to prevent shifting. Bright surface and precision-machined products receive custom wrappings and wooden crates. All shipments receive comprehensive anti-rust measures and specialized rust-preventative oil, guaranteeing the material arrives free from marine corrosion.
Frequently Asked Questions
Can you supply P650 non-magnetic steel to API specifications?
Yes. As an API Q1 certified manufacturer, ShunFu Metal produces P650 drill collars and hollow bars that fully comply with API performance requirements for non-magnetic drilling equipment, supported by rigorous UT and magnetic permeability testing.
What is the minimum order quantity for P650 non-magnetic hollow bars?
We offer maximum flexibility. For ready stock sizes, we accept single-piece orders with a 7-day lead time. For custom forged or rolled dimensions, the MOQ is typically 3 tons with a 30-day lead time.
Why are specialized surface treatments like roller burnishing critical for P650?
P650 is susceptible to transgranular SCC in certain downhole environments. Processes like roller burnishing, hammer peening, and shot peening introduce compressive residual stresses on the surface, effectively preventing SCC initiation and extending component lifespan.
How do you verify the non-magnetic properties of P650?
Every single collar is 100% tested using a proprietary magnetic probe-testing process. This ensures the relative magnetic permeability strictly meets the ≤ 1.005 requirement, and the results are certified with a printout for full traceability.
Request a Quote
Ensure the structural integrity and magnetic transparency of your downhole assemblies with certified P650 material. Contact our metallurgical team today to discuss your specific dimensional and melting route requirements.
Request a Quote for P650 Non-Magnetic Steel