Project Description
Introduction to P690 Nonmagnetic Steel
P690 nonmagnetic steel is a high-performance, pitting corrosion-resistant austenitic Cr-Ni-Mo-N alloy, specifically developed for the extreme operational demands of directional drilling and oilfield applications. Engineered to deliver a minimum yield strength of 965 N/mm² (140 ksi) alongside an exceptionally low relative magnetic permeability of ≤ 1.001, this material ensures reliable performance in MWD and LWD environments where magnetic interference must be strictly minimized.
Unlike conventional austenitic stainless steels, P690 achieves its high mechanical strength through a specialized cold-working process rather than relying on excessive carbon content. This methodology preserves its excellent intergranular corrosion resistance, ensuring longevity in aggressive downhole fluids. The high chromium, nickel, molybdenum, and nitrogen content provides robust defense against pitting corrosion. P690 serves as a trusted non-magnetic steel solution for critical downhole drilling components that demand both superior structural integrity and strict magnetic compliance.
Applications of P690 Nonmagnetic Steel
P690 nonmagnetic steel is indispensable in modern directional drilling operations, providing essential magnetic isolation for sensitive downhole measurement tools. Its combination of high strength and low permeability makes it the preferred choice for demanding subsurface environments.
- MWD/LWD non-magnetic drill collars
- Non-magnetic stabilizers and reamers
- Non-magnetic hollow bars for directional drilling subs
- Mining exploration drill rods and subs
- Downhole tool mandrels requiring low permeability
- Non-magnetic drill pipe accessories
- Heavy-wall hollow bars for aggressive drilling environments
Specifications & Standards
P690 nonmagnetic steel production and testing strictly adhere to internationally recognized standards, guaranteeing material integrity and operational safety for critical oilfield applications.
- ASTM A262: Practices for Detecting Susceptibility to Intergranular Corrosion in Stainless Steels (Practices A & E applied for intergranular SCC verification).
- ASTM E114: Standard Practice for Ultrasonic Pulse-Echo Straight-Beam Testing (Applied for 100% volumetric inspection).
- API 7-1: Specification for Rotary Drill Stem Elements (Product shape standard governing drill collars and stabilizers).
Available Sizes & Delivery
Hunan ShunFu Metal provides a comprehensive size range for P690 nonmagnetic steel to accommodate diverse downhole requirements. We supply hot-rolled rounds and hollow bars, alongside forged rounds and hollow bars. Dimensional availability extends across broad spectrums to support advanced processing capabilities.
Our production is backed by API-standard regularly calibrated heat treatment furnaces, ensuring precise metallurgical control. Furthermore, our precision machining capabilities include BTA deep hole drilling, CNC lathes and milling centers, and long-distance gunhole drilling, enabling us to deliver finished drill collars and hollow bars with exact internal and external geometries. Learn more about our advanced manufacturing infrastructure on our about ShunFu Metal page.
- Ready Stock (Common Sizes): Single-piece minimum order, approx. 7-day delivery.
- Custom Forged/Rolled Bars: MOQ of 3 tons, approx. 30-day delivery.
- Small-Batch Special Grades: Melted via our small induction furnace (3-5 tons MOQ).
- Large-Batch Orders: Fast delivery utilizing our 30-60 ton electric arc furnace.
Chemical Composition
The chemical composition of P690 nonmagnetic steel is carefully balanced to provide exceptional corrosion resistance and mechanical strength while maintaining minimal magnetic permeability.
| Element | Content (%) |
|---|---|
| C | max. 0.05 |
| Mn | 3.00 - 8.00 |
| Cr | 22.00 - 28.00 |
| Mo | 3.00 - 5.00 |
| N | min. 0.40 |
| Ni | 14.00 - 18.00 |
Note: As P690 is governed by a proprietary specification, the above represents the unified chemical requirement.
Melting & Processing Routes
Hunan ShunFu Metal offers flexible melting routes tailored to your project's severity. The standard route is EAF + AOD + LF + VD, ensuring high purity suitable for most drilling applications.
For elevated requirements, we offer ESR or PESR to drastically reduce macro-inclusions and segregation. For the most demanding downhole conditions requiring supreme structural homogeneity, the VIM + VAR route is available. We consult closely with clients to determine the most cost-effective and technically appropriate melting solution for their P690 requirements.
Mechanical Properties of P690 Nonmagnetic Steel
The mechanical properties of P690 nonmagnetic steel are tested at room temperature, achieved by a special cold-working process over the full length to ensure consistent performance throughout the component.
| Property | OD up to 9 1/4" | OD 9 1/2" and larger |
|---|---|---|
| Yield Strength (0.2% offset, min.) | 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.) | 162 J (120 ft.lb) | 162 J (120 ft.lb) |
| Endurance Strength (N=10⁵, min.) | ± 550 N/mm² (± 90 ksi) | ± 550 N/mm² (± 90 ksi) |
| Hardness (Brinell) | 350 - 450 HB | 350 - 450 HB |
Heat Treatment Process
Proper heat treatment is critical for P690 nonmagnetic steel to achieve the desired mechanical properties and prevent intergranular stress corrosion cracking.
| Process Stage | Parameters | Cooling Method |
|---|---|---|
| Warm Forging | Proprietary warm forging temperature range | Controlled |
| Quenching | Performed immediately after warm forging | Water Quench |
| Cold Working | Specialized cold-working process over full length | Ambient |
Surface Finish & Machining
ShunFu Metal provides comprehensive surface finishing and precision machining for P690 components to maximize fatigue life and prevent transgranular SCC. We offer turning, grinding, and CNC milling to achieve precise external dimensions with tolerances down to IT6-IT7 and surface roughness of Ra ≤ 1.6 µm.
For internal geometries, BTA deep hole drilling and long-distance gunhole drilling ensure straight, high-quality boreholes. To enhance downhole durability, critical surfaces undergo specialized treatments including hammer peening, roller burnishing (achieving Ra ≤ 0.4 µm), and shot peening. These processes induce compressive residual stress, effectively preventing transgranular stress corrosion cracking while ensuring superior dimensional accuracy.
Quality Assurance & Inspection
Quality assurance at ShunFu Metal spans pre-production, in-process, and final inspection stages. Every P690 nonmagnetic steel collar undergoes 100% magnetic probe testing to certify relative permeability (≤ 1.001) with official printouts. Ultrasonic inspection covers 100% of the volume per ASTM E114.
Intergranular corrosion susceptibility is rigorously tested per ASTM A262 Practices A and E, ensuring material integrity after quenching. We conduct comprehensive chemical analysis, mechanical property testing, dimensional verification, and metallographic examination. Certified EN 10204 3.1 mill certificates are standard; 3.2 certificates are available upon request. Third-party inspections by SGS or TÜV can be arranged. All processes operate strictly under our API Q1 and ISO 9001 certified quality management systems.
Packing & Shipping
Black-surface (as-forged/rolled) P690 bars are securely bundled with steel wire strapping, ensuring stability and preventing container damage during transit. For bright-surface or precision-machined drill collars and hollow bars, we utilize multi-layer protective packaging materials—including wooden crates and waterproof wrapping—specifically designed to preserve surface roughness and tight dimensional tolerances.
All products are coated with high-grade anti-rust oil, guaranteeing complete protection against corrosion throughout maritime shipping.
Frequently Asked Questions
Can you supply P690 nonmagnetic steel to API specifications?
Yes. As an API Q1 and ISO 9001 certified manufacturer, ShunFu Metal produces P690 non-magnetic drill collars and hollow bars fully compliant with API 7-1 specifications and related downhole tool standards.
What is the minimum order quantity for P690 non-magnetic drill collars?
For common sizes available in our ready stock, we accept single-piece orders with an approximate 7-day lead time. For custom forged sizes, the MOQ is typically 3 tons. We also support 3-5 ton small-batch melts and fast-turnaround 30-60 ton large batches.
How is the magnetic permeability of P690 verified?
Each P690 drill collar is 100% tested using our proprietary magnetic probe-testing process. The relative permeability is certified to be ≤ 1.001, and an official printout is provided with the mill certificate to guarantee compliance for MWD/LWD applications.
What surface treatments are applied to prevent stress corrosion cracking (SCC)?
To prevent transgranular SCC, ShunFu Metal applies hammer peening, roller burnishing, and shot peening. Intergranular SCC is prevented by strict quenching immediately after warm forging, verified via ASTM A262 Practices A and E testing.
