1.3949 Cr-Mn-N Steel Round Bar

Product Description

As detailed above, 1.3949 (EN/DIN designation X4CrMnN18-7, often associated with premium proprietary grades like BÖHLER P513) is a low-carbon, nitrogen-alloyed amagnetic (non-magnetic) austenitic steel.

Engineered primarily for applications requiring an absolute absence of magnetic permeability alongside high structural toughness, 1.3949 utilizes an optimized Chromium-Manganese-Nitrogen ($\text{Cr-Mn-N}$) metallurgical matrix. It serves as a dependable industrial standard for non-magnetic structural components, electrical shielding, and cryogenic hardware.

Chemical Composition (Mass Weight %)

The low carbon threshold ($\le 0.06\%$) ensures high resistance to intergranular corrosion by preventing chromium carbide precipitation at grain boundaries during hot forming or welding operations.

Core Technical Characteristics

• Magnetic Permeability ($\mu$): $\le 1.01 \text{ G/Oe}$ in the solution-annealed state. Because the austenitic matrix is microstructurally stable, it maintains an exceptionally low magnetic footprint even after light cold drawing, heavy machining, or surface impact stresses.

• Cryogenic Toughness: Unlike ferritic or martensitic steels, 1.3949 retains superb ductility and impact energy thresholds at sub-zero and cryogenic temperatures (down to $-196^\circ\text{C}$), preventing brittle failure modes.

• Corrosion Resistance: The $18\%$ Chromium content combined with interstitial Nitrogen provides general atmospheric corrosion and moisture resistance comparable to standard 304-series stainless steels.

Mechanical Properties (At Room Temperature)

Owing to the interstitial solid-solution strengthening provided by Nitrogen atoms packed into the face-centered cubic (FCC) lattice, 1.3949 displays a higher baseline yield strength than traditional non-magnetic 300-series stainless steels without nitrogen additions.

Heat Treatment Parameters

• Hot Forming / Forging: 1150°C down to 900°C. Controlled, uniform cooling protocols are recommended.

• Solution Annealing: 1000°C to 1080°C, followed immediately by rapid quenching in water or compressed air to fix the nitrogen completely into solid solution.

Machinability Guide

Like most high-manganese austenites, 1.3949 work-hardens rapidly under the cutting edge if tool rubbing is permitted.

• Maintain a rigid machining setup with sharp, coated carbide or cobalt tooling.

• Ensure a continuous, positive feed rate to cut beneath the work-hardened layer created by the previous pass.

• Use a generous flood of cooling lubricant to effectively manage thermal generation and evacuate chips cleanly.

Primary Applications for Round Bars

1.3949 round bars are specified across industries requiring durable structural components that must remain entirely transparent to magnetic fields:

• Electrical & Power Engineering: Retaining elements, non-magnetic sensor mounts, structural rings for generators, and high-voltage transformer enclosures.

• Cryogenic Engineering: Piping supports, valves, and structural framing operating in liquid nitrogen or liquid helium environments.

• Naval & Defense Systems: Components for mine-sweeping vessels, submarine specialized hardware, and marine structural pins operating near sensitive magnetic detection arrays.

• Industrial Fasteners: High-strength, amagnetic assembly bolts, studs, and heavy-duty clamping hardware.