1.3815 Cr-Mn-N Steel Round Bar

Product Description

1.3815 (X40MnCr18) is a specialized non-magnetic, austenitic steel. While it shares the "Cr-Mn-N" family lineage with the high-strength P900 or 1.3817 grades, 1.3815 is often utilized for its stable non-magnetic properties and excellent work-hardening capabilities in medium-stress industrial applications.

Material Specifications: 1.3815 (X40MnCr18)

This grade uses high manganese content to stabilize the austenite, which is an economical alternative to nickel-rich stainless steels.

Technical Characteristics

• Non-Magnetic Stability: The most critical feature is its low magnetic permeability ($\mu_r \approx 1.01$). Even after significant cold-forming or machining, it remains non-magnetic, which is vital for electrical and electronic interference shielding.

• Work Hardening: Like other high-manganese steels, it exhibits a high work-hardening rate. While the base material is relatively easy to form, any impact or pressure during service will significantly increase the surface hardness.

• Cryogenic Performance: It maintains high impact strength and toughness at sub-zero temperatures, preventing the "brittle transition" common in ferritic steels.

• Corrosion Resistance: It offers moderate resistance to atmospheric corrosion. However, due to the lower chromium content ($\approx 4\%$), it is not a "stainless" steel in the traditional sense and should not be used in highly acidic or saline environments without protection.

Common Applications

1.3815 round bars are typically converted into components for the power and electronics industries:

• Power Generation: Clamping plates, pressure rings, and spacer bolts for large generators and electric motors.

• Electrical Engineering: Components for high-voltage switchgear and transformers where eddy currents must be minimized.

• Cryogenic Vessels: Structural supports and fasteners for liquefied gas storage.

• Wear Parts: Bushings and pins subjected to abrasive environments.

Fabrication & Processing

• Machining: Challenging due to the high manganese content. It requires rigid machine tools, sharp carbide inserts, and constant feed rates. Avoid "dwelling" (letting the tool rub without cutting), as the surface will harden instantly and destroy the cutting edge.

• Heat Treatment: This material is typically delivered in the solution annealed condition (heated to $\approx 1050^\circ\text{C}$ and water-quenched). It does not respond to traditional quench-and-temper hardening; strength is increased only via cold working.

• Welding: Welding is possible using similar austenitic fillers, though care must be taken to manage the heat-affected zone (HAZ) to prevent carbide precipitation.

Comparison: 1.3815 vs. 1.3817

While 1.3815 (X40MnCr18) and 1.3817 (X55MnCrN18-4) are very similar, 1.3815 has slightly lower carbon and is generally applied where the extreme yield strength of the "X55" variant isn't required, offering a more cost-effective solution for standard non-magnetic hardware.