19MnCr18 Cr-Mn-N Steel Round Bar

Product Description

19MnCr18 or EN designation X8CrMnN18-18) is a highly engineered, fully austenitic Chromium-Manganese-Nitrogen (Cr-Mn-N) stainless steel.

Supplied typically as round bars and rods, this specific grade is designed as a nickel-free (or low-nickel) alternative to conventional austenitic steels. It is engineered to deliver an exceptional combination of ultra-high yield strength, high strain-hardening capacity, and absolute non-magnetic stability—even after heavy cold-working or deformation.

Chemical Composition (Typical Weight %)

The core metallurgy relies on high levels of Manganese and Nitrogen to act as strong austenite stabilizers, completely replacing or minimizing the need for expensive Nickel.

• Manganese (Mn) & Nitrogen (N): Work together to massively expand the single-phase austenite region. The high interstitial Nitrogen content dramatically boosts yield strength without compromising impact toughness.

• Chromium (Cr): Increases the solubility of nitrogen during melting and provides the base resistance to localized corrosion and oxidation.

Mechanical & Physical Properties

Because of its high interstitial nitrogen alloyed matrix, 19MnCr18 outperforms typical 300-series (like 316L) stainless steels by a wide margin regarding raw tensile parameters.

Mechanical Properties (Solution Annealed Condition)

• Yield Strength ($R_{p0.2}$): $\ge 450\text{ MPa}$ (Can surpass $1000\text{ MPa}$ when cold-worked or strain-hardened)

• Tensile Strength ($R_m$): $750 - 950\text{ MPa}$

• Elongation ($A_5$): $\ge 35\% - 40\%$ (Demonstrates remarkable uniform ductility)

• Impact Energy (KV): $\ge 70 - 85\text{ J}$

Physical Characteristics

• Magnetic Permeability ($\mu_r$): $\le 1.005\text{ H/m}$. It is virtually non-magnetic and structurally stable. Unlike common grades like 304, mechanical deformation will not trigger a transformation into magnetic martensite.

• Density: $7.70\text{ g/cm}^3$

Key Industry Standards & Equivalents

When verifying or cross-referencing this grade across global specifications:

• Material Number (WNr): 1.3816

• DIN / EN Designation: X8CrMnN18-18 (and closely related to the P900 or Mn18Cr18 series)

• ASTM Standard: Aligns closely with elements of ASTM A289 (Grade 2/3) for non-magnetic retaining rings.

• Commercial Proprietary Names: SINOXX 3816, Amagnit, or Staballoy variants.

Primary Applications for Round Bars

Round bars of 19MnCr18 are prioritized where dynamic physical loads and magnetic insulation are critical operational parameters:

• Generator Retaining Rings: Historically its most famous application; it encapsulates the rotor end-windings in turbo-generators where high centrifugal stress pairs with intense electromagnetic fields.

• Oil & Gas Downhole Drilling Tools: Non-magnetic drill collars, MWD (Measurement While Drilling) housing components, and stabilizing equipment that cannot interfere with directional magnetic sensors.

• Military & Defense Hardware: Non-magnetic structural elements for mine-countermeasure vessels, specialized submarine shafts, and naval weaponry assemblies.

• High-Strength Fasteners: Heavy-duty studs, clamping hardware, and non-magnetic bolts working in high-stress or cryogenic processing setups.

Processing & Fabrication Guidelines

• Machinability: 19MnCr18 has an extremely high work-hardening rate. Machining requires rigid machine tools, sharp cutting edges (preferably coated carbide), deep cuts, and positive feeds to ensure the tool tip cuts below the previously work-hardened surface layer.

• Heat Treatment: This grade cannot be hardened by thermal treatment. High mechanical performance is gained exclusively through cold work / strain hardening. Solution annealing is carried out between $1020^\circ\text{C} - 1120^\circ\text{C}$ followed by rapid water quenching.

• Welding: Good weldability due to the stable austenitic matrix. However, care must be taken with heat input to avoid nitrogen degassing or chromium carbide precipitation at grain boundaries. Matching or higher alloyed nitrogen-rich austenitic fillers are recommended.