EN X4CrNiMoN21-9-4 ISO X4CrNiMnMo21-9-4 High Nitrogen Steel Round Bar

Product Description

EN X4CrNiMoN21-9-4 and ISO X4CrNiMnMo21-9-4 High Nitrogen Stainless Steel Round Bars, Rods, and Bars

EN X4CrNiMoN21-9-4 and ISO X4CrNiMnMo21-9-4 represent European and international chemical designations for a high-purity, high-nitrogen austenitic stainless steel, standardized across global material systems under DIN Werkstoff Nr. 1.4472, UNS S31675, ASTM F1586, and ISO 5832-9. Manufactured through vacuum-arc remelting or pressurized electroslag remelting, this material is designed for high-fatigue orthopaedic surgical implants, trauma hardware, dental components, and precision engineering parts requiring non-magnetic behavior, biocompatibility, and elevated strength.

Standards and Equivalent Designations

• EN Chemical Standard: X4CrNiMoN21-9-4 / X4CrNiMnMo21-9-4

• DIN Werkstoff Nr.: 1.4472

• ISO Standard: ISO 5832-9 (Wrought high nitrogen stainless steel for surgical implants)

• ASTM Specification: ASTM F1586

• UNS Designation: S31675

• Commercial Trade Names: Rex 734, UGIPURE 4472, Chronifer M-1586

Chemical Composition Limits (Percent Weight)

The alloy contains a high-nitrogen addition in solid solution along with niobium for grain refinement and manganese to maintain nitrogen solubility:

• Chromium: 19.50 to 22.00 percent

• Nickel: 9.00 to 11.00 percent

• Manganese: 2.00 to 4.25 percent

• Molybdenum: 2.00 to 3.00 percent

• Nitrogen: 0.25 to 0.50 percent

• Niobium: 0.25 to 0.80 percent

• Carbon: 0.080 percent maximum

• Silicon: 0.75 percent maximum

• Phosphorus: 0.025 percent maximum

• Sulfur: 0.010 percent maximum

• Copper: 0.25 percent maximum

• Iron: Balance

Physical Properties

• Density: 7.88 grams per cubic centimeter (0.285 pounds per cubic inch)

• Elastic Modulus in Tension: 200 gigapascals

• Magnetic Permeability: Less than 1.005 (retains a non-magnetic austenitic structure even after cold working)

• Pitting Resistance Equivalent Number (PREN): 33.0 to 38.0

Mechanical Properties (ISO 5832-9 / ASTM F1586 Requirements)

Mechanical values vary based on bar diameter, cold-drawing levels, and heat-treatment condition:

Solution Annealed Condition

• Ultimate Tensile Strength: Minimum 740 megapascals (107 ksi)

• Yield Strength (0.2 Percent Offset): Minimum 430 megapascals (62 ksi)

• Elongation: Minimum 35 percent

• Typical Hardness: 200 to 250 Brinell

Cold-Worked / High-Strength Condition

• Ultimate Tensile Strength: Minimum 1000 megapascals (145 ksi)

• Yield Strength (0.2 Percent Offset): Minimum 700 to 750 megapascals (102 to 109 ksi)

• Elongation: Minimum 10 to 20 percent

• Typical Hardness: 30 to 38 Rockwell C

Primary Applications

• Medical Devices: Orthopaedic bone plates, intramedullary rods, trauma pins, spinal fixation screws, and joint prostheses.

• Dental Equipment: Precision dental shafts, surgical tools, and dental implants.

• High-Duty Industrial Parts: Non-magnetic valves, chemical processing components, and high-fatigue marine fasteners operating in halide-rich corrosive environments.