1.3817 Cr-Mn-N Steel Round Bar

Product Description

1.3817 is a high-nitrogen, austenitic stainless steel designated as X12CrMnNiN18-12-1. It is a specialized grade within the Chromium-Manganese-Nitrogen family, engineered to provide a very specific combination of high yield strength, high ductility, and absolute non-magnetic behavior.

While it shares similarities with 1.3816 (P550), the 1.3817 grade is often utilized when a slightly different balance of corrosion resistance and toughness is required for structural components in the energy and defense sectors.

1. Chemical Composition (Typical)

The addition of Nitrogen and Manganese allows this steel to remain austenitic (non-magnetic) even under extreme stress, while the small Nickel addition aids in maintaining toughness at low temperatures.

2. Physical and Mechanical Properties

Round bars of 1.3817 are known for their "work-horse" reliability in electromagnetic environments.

• Magnetic Permeability: $\mu \leq 1.01$. This grade is virtually transparent to magnetic fields, ensuring it does not interfere with sensors or cause heating through induction.

• Yield Strength ($R_{p0.2}$): $\geq 400$ MPa (nearly double that of 304L/1.4307).

• Tensile Strength ($R_m$): $750 - 950$ MPa.

• Impact Energy: Maintains excellent notch impact strength even in sub-zero or cryogenic conditions.

3. Key Applications

1.3817 round bars and rods are primarily specified for "Magnetic Silence" and high-load structural integrity:

• Electrical Power Generation: Clamping bolts, tension rods, and support structures for generators and large transformers where magnetic eddy currents must be avoided.

• Naval Engineering: Fasteners, drive shafts, and structural hardware for minesweepers and submarines requiring low magnetic signatures.

• Medical Equipment: Internal structural supports for MRI housing and high-field diagnostic rooms.

• Cryogenic Physics: Frameworks for superconducting magnets and laboratory equipment where magnetic flux must be strictly controlled.

4. Technical Comparison: 1.3817 vs. 1.3816

• Manganese Content: 1.3817 typically has lower Manganese ($\approx 12\%$) compared to 1.3816 ($\approx 18\%$).

• Machinability: Because of the slightly lower Manganese content, 1.3817 can be marginally easier to machine than the ultra-high Manganese grades, though it still work-hardens significantly faster than standard stainless steels.

• Purpose: 1.3816 is the "extreme" version for oilfield drill collars, while 1.3817 is often the "industrial" version for high-end electrical and structural components.

5. Processing Guidelines

• Cold Working: This material responds very well to cold drawing. If you require higher strength than the annealed state, cold-worked rods can reach yield strengths exceeding $700$ MPa while remaining non-magnetic.

• Machining: Use slow cutting speeds and high feed rates. It is vital to use sharp, cobalt-alloyed high-speed steel or carbide tools to penetrate the surface before it can work-harden.

• Surface Finish: Due to its high hardness and homogeneous austenitic structure, it can be polished to a very high mirror finish, which is beneficial for both aesthetics and corrosion resistance.