Project Description
Magnadur 601 Non-Magnetic Stainless Steel Overview
Magnadur 601 is an advanced non-magnetic stainless steel originally developed by Deutsche Edelstahlwerke GmbH, engineered specifically for the extreme demands of downhole measurement and drilling environments. As a premium austenitic alloy, its core strength lies in its exceptional magnetic neutrality, maintaining a permeability of μ < 1.01. This level of magnetic transparency is critical for the accuracy of sensitive directional surveying equipment, preventing interference that could lead to costly trajectory errors.
Beyond its magnetic stability, this proprietary grade offers a superior synergy of high mechanical strength and outstanding corrosion resistance. Its carefully balanced chemical composition—featuring 16.5-17.5% chromium, 4.20-5.00% nickel, 2.00-2.80% molybdenum, and 0.40-0.50% nitrogen—provides robust defense against stress corrosion cracking (SCC) and pitting corrosion in aggressive chloride-rich downhole fluids. With a Pitting Resistance Equivalent Number (PREN) reaching up to 35, it outperforms conventional non-magnetic grades, ensuring structural integrity and operational reliability where failure is not an option.
Key Applications for Magnadur 601
This alloy is predominantly utilized in the Oil & Gas, Mining, and Drilling sectors where magnetic interference and severe corrosive conditions coincide. In these demanding applications, magnetic distortion can compromise downhole data, while H2S and CO2 environments threaten structural integrity. Specific downstream products and application scenarios include:
- Measurement-While-Drilling (MWD) housings: Ensures zero magnetic distortion for precise directional drilling data.
- Non-magnetic drill collars: Provides structural weight and rigidity without interfering with survey tools, complementing standard drill pipe strings.
- Downhole measurement instruments: Protects sensitive electronic components from both mechanical stress and corrosive fluids.
- Stabilizers and steering tools: Maintains wellbore trajectory in highly aggressive sour service environments, offering an alternative to standard CRA piping in specific directional tools.
- Logging-While-Drilling (LWD) mandrels: Resists SCC under high tensile loads in deep, hot wells.
- Mining drill rods: Offers durability and non-magnetic properties for specialized geological exploration.
Specifications & Standards
The material is classified as a non-standard proprietary special steel and is not explicitly codified under generalized national standards like DIN, EN, or JIS. However, its manufacturing, testing, and performance verification strictly comply with established industry protocols:
- ASTM Corrosion Testing Protocols: Governs the validation of its exceptional pitting and SCC resistance, ensuring it withstands aggressive downhole fluids.
- PREN Evaluation: Calculated per industry-standard formulas (%Cr + 3.3x %Mo + 16x %N), achieving 29.5–35, surpassing many standard non-magnetic grades.
- API Standards: Applicable for material property verification and dimensional tolerances in oilfield drilling equipment.
- Product Shapes: Primarily manufactured and supplied as forged round bars, rolled round bars, and hollow bars.
Available Sizes & Delivery Options
SHUNFU METAL provides this grade across a versatile dimensional range to accommodate diverse downhole tool requirements. To guarantee end-product performance, we process the material using our API-compliant, regularly calibrated heat treatment furnaces. Our precision machining capabilities include BTA deep-hole drilling for hollow bars, CNC lathes and milling machines for complex geometries, and long-distance gunhole drilling for extended MWD housings, ensuring superior bore concentricity.
| Product Shape | Dimension Range |
|---|---|
| Rolled Round Bars & Flat Bars | Diameter/thickness from 20 mm to 120 mm |
| Forged Round Bars & Flat Bars | Diameter/thickness from 120 mm up to 280 mm |
| Hollow Bars | Outer diameter from 75 mm (3") to 250 mm (10") with customizable wall thicknesses |
Lead Time & Minimum Order Quantity
- Ready Stock: Available for common sizes; single-piece MOQ; approx. 7-day delivery.
- Custom Forging/Rolling: MOQ typically 3 tons; approx. 30-day delivery.
- Small Batch Special Melting: Induction furnace available; 3–5 tons MOQ.
- Large Batch Orders: 30–60 ton EAF capacity; fast delivery turnaround.
Chemical Composition
The precise chemical formulation of this proprietary alloy distinguishes it from standard AISI non-magnetic grades. The high manganese content (18.0-20.0%) stabilizes the austenitic structure without relying solely on nickel, maintaining low magnetic permeability even after severe cold working. The deliberate addition of molybdenum and nitrogen synergistically enhances pitting resistance and yields the high PREN value. Low carbon content ensures excellent weldability and minimizes carbide precipitation.
| Element | C | Si | Mn | P | S | Cr | Ni | Mo | N |
|---|---|---|---|---|---|---|---|---|---|
| Min. | – | – | 18.0 | – | – | 16.5 | 4.20 | 2.00 | 0.40 |
| Max. | 0.05 | 0.30 | 20.0 | 0.03 | 0.005 | 17.5 | 5.00 | 2.80 | 0.50 |
Melting & Processing Routes
SHUNFU METAL offers flexible melting routes tailored to your application's severity. Clients can negotiate the optimal melting strategy with our engineering team to balance performance and cost.
- Conventional Route: EAF + AOD + LF + VD, ensuring high purity for standard oilfield needs.
- Elevated Cleanliness: ESR or PESR is available for improved homogeneity, reducing delta ferrite and improving transverse toughness.
- Critical MWD Tools: VIM + VAR (Double Vacuum) route for ultimate structural integrity and minimized non-metallic inclusions to maximize fatigue life.
Mechanical Properties
The mechanical properties of this alloy at room temperature, in the forged and work-hardened condition, demonstrate its capability for extreme downhole stresses. Because it is a fully austenitic grade, it achieves its high yield strength through strain hardening rather than quench-and-temper treatments. This process reliably yields a minimum tensile strength of 1035 MPa across all diameter ranges, maintaining a minimum elongation of 20% and impact energy of 135 J to withstand shock loads.
| Property | Diameter 75–235 mm (3–9¼") | Diameter >235–250 mm (>9¼–9¾") |
|---|---|---|
| Hardness (HB) | 300–400 | 300–400 |
| Min. Yield Strength (Rp0.2) | 965 MPa (140 ksi) | 900 MPa (130 ksi) |
| Min. Tensile Strength (Rm) | 1035 MPa (150 ksi) | 1035 MPa (150 ksi) |
| Min. Elongation (A5) | 20% | 20% |
| Min. Reduction of Area (Z) | 50% | 50% |
| Min. Impact Energy (AV) | 135 J (100 ft-lbs) | 135 J (100 ft-lbs) |
| Min. Fatigue Strength | 445 MPa (65 ksi) | 445 MPa (65 ksi) |
Heat Treatment Process
The material achieves its exceptional mechanical strength and non-magnetic stability through a specific forging and work-hardening cycle rather than conventional quench-and-temper treatments. Solution annealing at 1050–1100°C, followed by water quenching, restores ductility and homogenizes the structure before the final strain strengthening. Work hardening is then performed at ambient or controlled room temperatures through continuous mechanical strain via forging or rolling.
| Treatment Process | Temperature Range | Holding Time | Cooling Method |
|---|---|---|---|
| Solution Annealing (Pre-Work Hardening) | 1050–1100°C | Based on cross-section | Water Quenching |
| Work Hardening (Strain Strengthening) | Ambient / Controlled Room Temp | Continuous pass | Mechanical strain via forging/rolling |
Surface Finish & Machining Capabilities
SHUNFU METAL delivers the alloy with surface finishes tailored to downhole tool specifications. Black or skin-pass forged bars are supplied as-is for general machining. For precision requirements, we offer turning (Ra 1.6–6.3 µm), grinding (Ra 0.4–1.6 µm), and milling to achieve tight dimensional tolerances down to ±0.01 mm.
Our specialized deep-hole processing includes BTA boring (Ra 0.8–3.2 µm) for hollow bars and long-distance gunhole drilling for MWD mandrels, ensuring superior bore concentricity and smooth internal surfaces. Roller burnishing and shot peening are available to enhance inner surface fatigue resistance and final surface integrity, extending the operational lifespan of the finished tool.
Quality Assurance & Inspection
Our quality assurance encompasses pre-production ingot verification, in-process dimensional checks, and comprehensive post-production testing. Ultrasonic Testing (UT) is executed per ASTM E2375 / SEP 1921 to ensure internal soundness, eliminating the risk of subsurface defects. We conduct full chemical analysis, mechanical testing, and metallographic examination.
Corrosion testing per ASTM protocols can be arranged upon request. SHUNFU METAL issues EN 10204 3.1 certificates standardly, with 3.2 certification available via SGS or TÜV third-party inspection for international project compliance. All processes operate under our API Q1 and ISO 9001 quality management systems.
Packing & Shipping Details
Black-skin forged bars are securely fastened with steel wire bundles, ensuring container stability during transit without risking mechanical damage. For bright-surface and precision-machined MWD housings or hollow bars, we apply multi-layer protective wrapping using VCI film and custom crates to preserve surface roughness and dimensional tolerance.
All products are thoroughly coated with specialized anti-rust oil, guaranteeing complete protection against marine corrosion during overseas shipping, ensuring the material arrives in pristine condition ready for final fabrication.
Frequently Asked Questions
Can you supply Magnadur 601 to API specification?
While this grade is a proprietary DEW alloy rather than a standard API codified steel, SHUNFU METAL manufactures and tests the material in strict compliance with API equipment standards and our API Q1 certified quality system, ensuring it meets the rigorous demands of downhole drilling tools.
What is the minimum order quantity for this non-magnetic steel?
We maintain ready stock for common drill collar and MWD sizes, allowing for a single-piece MOQ with a 7-day delivery. For custom forged dimensions, the MOQ is typically 3 tons with a 30-day lead time.
How does Magnadur 601 compare to other non-magnetic alloys for MWD tools?
It outperforms earlier grades like 501 and 509 due to higher molybdenum content (2.00-2.80%). This provides a significantly higher PREN up to 35 and superior resistance to stress corrosion cracking, even under tensile stresses below 0.5 x yield strength in sour service environments.
Which melting route do you recommend for Magnadur 601?
For standard MWD housings, EAF + AOD + LF + VD provides excellent purity. For extreme-depth, high-stress applications where fatigue life is critical, we recommend the ESR or VIM + VAR routes to minimize non-metallic inclusions and maximize structural homogeneity.
Request a Quote for Magnadur 601
Ready to specify Magnadur 601 for your next downhole project? Contact our sales team to discuss dimensions, melting routes, and precision machining requirements.
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