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TWZ-3 Non-Magnetic Steel

Home/Non Magnetic Steel, Product/TWZ-3 Non-Magnetic Steel
TWZ-3 Non-Magnetic Steel2026-04-21T07:17:57+00:00

Project Description

Introduction to TWZ-3 Non-Magnetic Steel

TWZ-3 non-magnetic steel drill collar bar for directional drilling
TWZ-3 non-magnetic drill collar round bar

TWZ-3 non-magnetic steel is a high-strength austenitic alloy specifically engineered for the extreme demands of directional drilling operations. Characterized by its deliberate addition of manganese, chromium, and nitrogen, this advanced material achieves a minimum yield strength of 140 KSI (965 MPa) while maintaining exceptionally low magnetic permeability. This critical combination ensures zero interference with downhole MWD and LWD sensors, allowing operators to maintain precise wellbore trajectory control.

Beyond its magnetic stability, TWZ-3 offers outstanding toughness, excellent resistance to stress-corrosion cracking, and reliable durability under severe torsional and bending stresses. These properties make it an indispensable material for critical bottom hole assemblies. You can explore our complete range of non-magnetic steel products for various downhole applications.

Equivalent Grades and Standards

Equivalent grade and standard reference for TWZ-3 steel
Grade Standard / Specification Equivalent / Reference
TWZ-3 Enterprise / Domestic Spec Conforms to API Spec 7-1 140 KSI NMDC requirements

Key Applications in Directional Drilling

TWZ-3 non-magnetic steel is primarily utilized in downstream drilling components where magnetic interference must be strictly eliminated. Its high strength and low permeability make it the preferred choice for sensitive surveying equipment housed within the drilling string. We supply materials specifically tailored for manufacturing high-performance drill collar products.

Oil and Gas Drilling

  • Non-magnetic drill collars (NMDC)
  • Non-magnetic heavy-weight drill pipes (NMHWDP)
  • Non-magnetic stabilizers
  • MWD/LWD tool housings and carriers
  • Directional drilling bottom hole assemblies (BHA)

Mining and Rock Drilling

  • Non-magnetic guide rods for precision surveying equipment
  • Structural components for automated mining navigation systems

Drilling Engineering

  • Custom non-magnetic subs and crossover subs
  • Pressure-containing downhole sensor sleeves

Specifications and Industry Standards

TWZ-3 is manufactured to meet stringent international standards governing downhole non-magnetic components. Compliance with these specifications guarantees consistent performance and interoperability within global drilling operations.

  • API Spec 7-1: Rotary Drill Stem Elements (Covers drill collars, stabilizers, and HWDP)
  • API Spec 7-2: Threading and Gauging for Rotary Drill Stem Elements
  • SY/T 5144: Chinese Petroleum Industry Standard for Drill Collars
  • Product Shapes: Forged round bars, Hollow bars (Suitable for direct machining into drill collars)

Available Sizes and Delivery Options

SHUNFU METAL provides comprehensive dimensional flexibility for TWZ-3, demonstrating our superior hot-working and processing capabilities. We supply hot-rolled and forged round bars (OD: 80mm – 350mm) and forged flat bars, alongside hollow bar solutions tailored for drill collar production.

Our manufacturing infrastructure features API-standard regularly calibrated heat treatment furnaces ensuring precise metallurgical properties. For precision downhole requirements, we operate BTA deep hole drilling machines, CNC lathes and milling centers, and long-distance gunhole drilling equipment, guaranteeing strict borehole concentricity and straightness.

Delivery Programs

  • Ready Stock (Common Sizes): Single-piece orders available; delivery within approximately 7 days.
  • Custom Forged/Rolled Bars: Minimum order quantity (MOQ) of 3 tons; delivery within approximately 30 days.
  • Small-Batch Special Grades: Melted via our small induction furnace (3–5 tons MOQ).
  • Large-Batch Orders: Produced via 30–60 ton EAF routes for rapid, mass-scale delivery.

Chemical Composition of TWZ-3

Chemical composition limits for TWZ-3 austenitic non-magnetic steel (weight %)
Element TWZ-3 (%)
C≤ 0.04
Si0.10 – 0.60
Mn18.0 – 21.0
P≤ 0.03
S≤ 0.02
Cr16.0 – 18.0
Ni0.50 – 1.50
Mo0.40 – 0.80
N0.50 – 0.80
Nb≤ 0.08
Cu≤ 0.20
Al≤ 0.025

Melting and Processing Routes

SHUNFU METAL offers flexible melting routes for TWZ-3 non-magnetic steel to match your specific reliability requirements. The conventional route utilizes EAF + AOD + LF + VD, utilizing AOD to precisely control ultra-low carbon and nitrogen levels.

For elevated micro-cleanliness and homogeneity, we offer ESR or PESR routes. For the most demanding critical-service applications, VIM + VAR (Double Vacuum) melting is available. Clients can negotiate with our metallurgists to select the optimal balance of purity and cost. To learn more about our facility and metallurgical expertise, visit about ShunFu Metal.

Mechanical Properties

Mechanical properties of TWZ-3 steel under High Strength (HS) and Lower Strength (LS) conditions
Condition Diameter Range (mm) Rp0.2 (MPa) Rm (MPa) A (%) Z (%) AkV (J) HBW
HS (High Strength)≥80 ~ ≤180≥ 965≥ 1035≥ 20≥ 50≥ 100≥ 290
HS (High Strength)>180 ~ 280≥ 900≥ 1000----
LS (Lower Strength/High Ductility)≥80 ~ ≤180≥ 825≥ 930≥ 25≥ 50≥ 130≥ 277
LS (Lower Strength/High Ductility)>180 ~ 280≥ 770≥ 900----

Heat Treatment Parameters

Solution annealing parameters for TWZ-3 non-magnetic steel
Treatment Type Temperature Range Soaking Time Cooling Method
Solution Annealing 1000°C – 1050°C 1.5 hrs per 25mm section Water Quenching

Surface Finish and Precision Machining

To achieve the strict tolerances required for downhole tool assemblies, SHUNFU METAL provides extensive surface finishing and precision machining for TWZ-3 products. Rough turning delivers an Ra of 3.2–6.3 μm for semi-finished bars. We perform CNC turning and milling to achieve dimensional tolerances up to ±0.01mm.

For internal bores, BTA boring and long-distance gunhole drilling maintain precise concentricity, achieving an internal Ra of 1.6–3.2 μm. Roller burnishing is applied to inner diameters to reach an Ra ≤ 0.4 μm, while external grinding finishes surfaces to Ra ≤ 0.8 μm. External shot peening can be specified to enhance surface compressive stress.

Quality Assurance and Inspection Protocols

SHUNFU METAL enforces rigorous quality control throughout production. Pre-production verifies raw material chemistry. In-process checks monitor dimensions and heat treatment parameters via API-calibrated furnaces. Post-production includes 100% Ultrasonic Testing (UT) per ASTM E2375/API Spec 7-1 to ensure internal soundness.

Furthermore, we conduct mandatory magnetic permeability testing (μr ≤ 1.005), tensile and impact testing, metallographic examination, and dimensional verification. We issue EN 10204 3.1 certificates as standard; 3.2 certifications via SGS or TÜV are available upon request. All processes operate under our API Q1 and ISO 9001 quality management systems.

Packing and Shipping Logistics

For black and skin-pass products, we secure bundles with heavy steel wire strapping to prevent movement and container damage during transit. For bright surfaces and precision-machined TWZ-3 drill collars and bars, we apply multi-layer protective wrapping including VCI film and waterproof cloth.

This safeguards surface roughness and dimensional accuracy. All products are coated with specialized anti-rust oil, guaranteeing complete protection against corrosion throughout international ocean freight.

Frequently Asked Questions

Can you supply TWZ-3 to API specification?

Yes. TWZ-3 non-magnetic steel is engineered to meet the mechanical requirements of API Spec 7-1 for 140 KSI non-magnetic drill collars. As an API Q1 certified manufacturer, SHUNFU METAL ensures full compliance with API dimensional, threading, and metallurgical standards.

What is the minimum order quantity for TWZ-3?

We maintain ready stock for standard NMDC sizes, allowing for single-piece purchases with a 7-day delivery. For custom forged requirements, the MOQ is typically 3 tons. For specialized small-batch chemistry variations, we can melt 3-5 tons using our induction furnace.

How do you guarantee the non-magnetic properties of TWZ-3?

Our API-calibrated heat treatment furnaces execute precise solution annealing and water quenching, ensuring the austenitic structure remains fully stable. We perform mandatory magnetic permeability testing on every lot, certifying a relative permeability (μr) of ≤ 1.005.

What deep-hole drilling capabilities do you offer for TWZ-3 hollow bars?

We operate advanced BTA deep-hole boring machines and long-distance gunhole drilling equipment. This allows us to produce seamless hollow bars and drill collars with deep, straight internal bores, tight concentricity, and superior internal surface finishes directly from forged rounds.

Request a Quote for TWZ-3

Need reliable TWZ-3 non-magnetic steel for your next directional drilling project? Our metallurgical team is ready to assist you with specifications, custom sizes, and delivery schedules. Contact SHUNFU METAL today to discuss your requirements.

Request a Quote
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