Staballoy AG17 Cr-Mn-N Steel Round Bar

Product Description

Staballoy AG17 is a high-performance, non-magnetic austenitic stainless steel belonging to the Chromium-Manganese-Nitrogen (Cr-Mn-N) family. It is specifically engineered for the oil and gas industry, primarily for use in drill collars and downhole tools where high mechanical strength and absolute magnetic neutrality are required.

Like other Staballoy grades, AG17 achieves its properties through high nitrogen alloying and cold-working rather than traditional heat treatment.

1. Chemical Composition (Typical)

The alloy replaces expensive Nickel with Manganese and Nitrogen to stabilize the austenite phase and increase strength.

2. Key Performance Characteristics

• Magnetic Permeability: $\mu \leq 1.005$. It remains non-magnetic even after severe mechanical stress, which is vital for directional drilling sensors (MWD/LWD) that rely on the Earth's magnetic field.

• High Strength: In its standard "hot-finished and cold-expanded" state, AG17 offers yield strengths significantly higher than 300-series stainless steels.

• Corrosion Resistance: It is specifically designed to resist Stress Corrosion Cracking (SCC) in chloride-rich environments (brine and drilling muds) and is resistant to intergranular corrosion.

• Gall Resistance: The high manganese content provides better resistance to "galling" on threaded connections compared to standard austenitic steels.

3. Mechanical Properties

The properties of Staballoy AG17 are typically determined by the level of cold work (compression or expansion) applied during manufacturing.

4. Primary Applications

Staballoy AG17 round bars are primarily used in the upstream energy sector:

• Non-Magnetic Drill Collars (NMDC): Providing weight on the drill bit while remaining "invisible" to magnetic survey tools.

• MWD/LWD Housings: Protecting sensitive electronic measurement equipment in the drill string.

• Stabilizers & Subs: Structural components in directional drilling assemblies.

• Heavy Duty Fasteners: Used in marine or subsea environments where magnetic interference must be avoided and high tensile loads are present.

5. Technical Comparison: AG17 vs. P550/1.3816

Staballoy AG17 is often considered the industry equivalent to P550 (1.3816). Both are "18-18" type steels (18% Cr, 18% Mn). AG17 is favored in North American oilfields, while the Werkstoff designations are more common in European engineering.

6. Processing and Handling

• Machining: Due to its extreme work-hardening rate, AG17 requires rigid machine tools and sharp carbide inserts. It is critical to maintain a constant feed; if the tool dwells, the material surface will harden to a point where subsequent passes may fail.

• Surface Treatment: Often provided with a "roller-burnished" or "shot-peened" surface in the bore of drill collars to further increase resistance to fatigue and stress corrosion.

• Welding: Generally not recommended if the high-strength properties must be maintained, as the heat of welding will "soften" (anneal) the cold-worked structure.