Project Description
P750 HS Non-Magnetic Steel Overview
P750 HS non-magnetic steel is an advanced austenitic chromium-nickel-nitrogen (Cr-Ni-N) alloy specifically engineered for demanding oilfield environments. Characterized by its extremely low relative magnetic permeability (≤ 1,001) and exceptional pitting corrosion resistance comparable to nickel-base alloys, this material ensures reliable directional drilling performance where magnetic interference must be strictly minimized. Its high yield strength of 1104 N/mm² is achieved through a specialized cold-working process applied over the full length of the bar, making it an optimal choice for manufacturing downhole tools that require both structural integrity and strict non-magnetic properties.
By combining high nitrogen content with a low carbon matrix, P750 HS effectively prevents material sensitization during warm forging, guaranteeing superior intergranular corrosion resistance. This unique chemical balance allows the steel to maintain its mechanical and magnetic properties even after severe thermal cycling downhole. For engineers seeking comprehensive non-magnetic steel solutions, SHUNFU METAL provides unmatched technical expertise and manufacturing precision.
Primary Downhole Applications
The superior magnetic neutrality and structural strength of P750 HS make it indispensable for critical measurement-while-drilling (MWD) and logging-while-drilling (LWD) systems. Magnetic interference can severely compromise directional sensor accuracy, leading to costly wellbore trajectory deviations. By utilizing P750 HS, operators ensure that their downhole measurement tools remain unaffected by the drill string's magnetic field.
- Non-Magnetic Drill Collars (NMDC) for directional drilling and steering systems
- Non-Magnetic Stabilizers integral to MWD/LWD telemetry housings
- Non-Magnetic Compressional Sleeves for downhole pressure monitoring
- Non-Magnetic Housings protecting sensitive electronic measurement tools
- Drill string components requiring strict magnetic neutrality near sensors
- Mining exploration drilling tools exposed to severely corrosive environments
SHUNFU METAL's premium drill collar products leverage this material to deliver maximum reliability in extended-reach and horizontal drilling applications. Furthermore, our specialized hollow bar stock provides the ideal starting geometry for machining complex downhole housings.
P750 HS Non-Magnetic Steel Chemical Composition
The carefully engineered austenitic Cr-Ni-N matrix of P750 HS ensures both high strength and absolute magnetic stability. The high nitrogen content acts as a potent austenite stabilizer, replacing carbon to eliminate sensitization risks, while the substantial chromium and molybdenum additions provide pitting resistance equivalent to premium nickel alloys.
| Element | P750 HS (%) |
|---|---|
| C | max. 0.03 |
| Mn | 1.50 - 3.00 |
| Cr | 26.50 - 29.50 |
| Mo | 2.00 - 4.00 |
| N | min. 0.20 |
| Ni | 28.00 - 31.50 |
Mechanical Properties and Strength Data
The exceptional mechanical performance of P750 HS is achieved through a full-length special cold-working process, ensuring uniform yield strength and hardness from surface to core. This process guarantees that the material will not yield under extreme downhole compressive and bending loads, maintaining dimensional stability for critical measurement tool housing threads.
| Property | Value (ksi) | Value (N/mm²) |
|---|---|---|
| Yield Strength (min., 0.2% offset) | 160 | 1104 |
| Tensile Strength (min.) | 165 | 1139 |
| Elongation (min.) | 10% | 10% |
| Reduction of Area (min.) | 50% | 50% |
| Impact Energy (min.) | 80 ft.lb | 110 J |
| Endurance Strength (min., N=10⁵) | ± 80 | ± 550 |
| Hardness Brinell | 300 - 420 HB | 300 - 420 HB |
Industry Specifications and Standards Compliance
P750 HS is primarily governed by proprietary specifications tailored to extreme downhole demands. However, SHUNFU METAL manufactures and tests all products within the rigorous framework of international oilfield standards to ensure interchangeability and baseline quality assurance.
- API Spec 7-1 / API Spec 5DS: Governing standards for drill collars, stabilizers, bars, and hollow bars.
- ASTM A262: Standard practices for detecting intergranular corrosion (Practices A and E utilized).
- ASTM E114: Standard for ultrasonic inspection of bars and hollow bars to ensure internal soundness.
Melting Routes and Processing Capabilities
Conventional and Advanced Melting Routes
SHUNFU METAL offers flexible melting routes tailored to your specific technical requirements and risk profiles. The conventional route utilizes EAF (Electric Arc Furnace) + AOD + LF + VD, ensuring high-quality baseline material with precise nitrogen and carbon control. For enhanced purity and structural homogeneity essential for fatigue-critical components, we offer ESR (Electro-Slag Remelting) or PESR.
For the most demanding critical applications requiring ultimate reliability and inclusion-free material, the VIM (Vacuum Induction Melting) + VAR (Vacuum Arc Remelting) route is available. Customers can negotiate directly with our engineering team to learn about SHUNFU METAL's manufacturing facilities and select the optimal melting solution based on specific downhole operational demands.
Heat Treatment Process
The thermal processing of P750 HS is carefully controlled to preserve its austenitic structure and prevent sensitization. Warm forging followed by rapid quenching prevents carbide precipitation and intergranular stress corrosion cracking (SCC). Subsequently, a special cold-working process is applied over the full bar length to achieve the required high yield strength and hardness, ensuring uniform mechanical performance without relying on precipitation hardening mechanisms.
- Warm Forging + Quenching
- Purpose: Prevent material sensitization and intergranular SCC. Cooling Method: Rapid Quenching.
- Special Cold-Working Process
- Purpose: Achieve required high yield strength and hardness over the full length. Method: Ambient / Mechanical Processing.
Surface Finish, Machining, and Quality Assurance
SHUNFU METAL provides comprehensive surface finishing and precision machining for P750 HS components. We supply as-forged (black) surfaces or process to precise requirements via turning, grinding, milling, and CNC precision machining. For deep-hole requirements characteristic of drill collars and MWD housings, we utilize BTA boring and long-distance gunhole drilling.
To enhance fatigue life and prevent transgranular SCC—critical failure modes for downhole tools—specialized surface treatments such as roller burnishing, hammer peening, and shot peening are applied. These processes induce beneficial compressive residual stress on the component surface, significantly extending service life. Our machining capabilities achieve superior surface roughness (Ra ≤ 0.8 μm for burnished/ground surfaces) and strict dimensional tolerances (±0.05 mm).
Quality control at SHUNFU METAL spans pre-production, in-process, and post-production phases. All P750 HS non-magnetic steel products undergo 100% ultrasonic inspection according to ASTM E114 and 100% magnetic permeability probe testing, with permeability printouts certified for every collar. Chemical composition analysis, mechanical property testing, and metallographic examination are systematically executed. Intergranular corrosion resistance is strictly verified per ASTM A262 Practices A and E. For projects requiring superior pitting resistance, our corrosion-resistant alloy piping solutions provide complementary material options.
We issue EN 10204 3.1 certificates as standard, with 3.2 certificates available upon request. Third-party inspections by SGS or TÜV can be arranged. SHUNFU METAL operates under API Q1 and ISO 9001 quality management systems, guaranteeing full traceability and compliance.
Available Sizes, Delivery, and Packaging
SHUNFU METAL supplies P750 HS in a comprehensive range of sizes to accommodate diverse downhole tool requirements. We offer rolled round bars, forged round bars, forged flat bars, and hollow bars. Our dimensional capabilities extend broadly, supported by API-standard calibrated heat treatment furnaces and advanced precision machining equipment.
- Common Sizes
- Available from ready stock. Single-piece orders accepted with delivery within approximately 7 days.
- Custom Forgings / Rolled Material
- Minimum order quantity typically 3 tons, with delivery within approximately 30 days.
- Small Batch Special Grades
- Small induction furnace available for melting from 3-5 tons, accommodating specialized project requirements.
- Large Volume Orders
- 30-60 ton EAF capacity ensures fast turnaround for major drilling programs.
Black-skin (as-forged) products are securely bundled with steel wire strapping to prevent shifting and container damage during transit. For bright-surface and precision-machined P750 HS bars and hollows, multiple protective packaging materials—including wooden crates and shock-absorbing wraps—are utilized. Anti-rust oil is uniformly applied to all products, ensuring comprehensive protection against corrosion throughout long-distance ocean shipping.
Frequently Asked Questions
Can you supply P750 HS to API specification?
Yes. SHUNFU METAL is an API Q1 and ISO 9001 certified manufacturer. We produce P750 HS drill collars and hollow bars fully compliant with API Spec 7-1 and API Spec 5DS, utilizing API-calibrated heat treatment furnaces and rigorous testing protocols.
What is the minimum order quantity for P750 HS?
We offer flexible MOQs. Common sizes are available from our ready stock with single-piece minimums and a 7-day turnaround. Custom forged or rolled material typically requires a 3-ton MOQ, while small batch special grades can be melted from 3-5 tons in our induction furnace.
How do you guarantee the non-magnetic properties of P750 HS?
Each collar is 100% tested via a proprietary magnetic probe-testing process. We guarantee a relative magnetic permeability of ≤ 1,001, and provide a certified printout of the probe test with every delivery to ensure absolute magnetic neutrality for directional drilling.
What surface treatments are available to prevent stress corrosion cracking (SCC)?
To prevent transgranular SCC, we offer specialized surface treatments including hammer peening, roller burnishing, and shot peening. These processes induce beneficial compressive residual stress on the component surface, significantly enhancing fatigue life.