ASTM F1586 ISO 5832-9 High Nitrogen Steel Round Bar, Rods & Bars

Product Description

ASTM F1586 and ISO 5832-9 High Nitrogen Stainless Steel Round Bars, Rods, and Bars

ASTM F1586 and ISO 5832-9 define the international medical and technical standard for high-nitrogen, high-purity austenitic stainless steel bar and wire stock. Designated under the Unified Numbering System as UNS S31675 and in Europe as DIN Werkstoff Nr. 1.4472 (X2CrNiMoN21-16-5-4), this alloy—commercially recognized as Rex 734, UGIPURE 4472, or Chronifer M-1586—is manufactured using vacuum arc remelting or electroslag remelting processes. It was developed specifically to replace standard 316L (ASTM F138) in orthopaedic implants and high-fatigue medical hardware by offering significantly higher mechanical strength, improved fatigue limits, and superior resistance to pitting and crevice corrosion.

Standards and Specifications

Primary governing specifications include ASTM F1586 for wrought nitrogen-strengthened 21 chromium, 10 nickel, 3 manganese, 2.5 molybdenum stainless steel for surgical implants, ISO 5832-9 for surgical implants, UNS S31675, and European standard DIN Werkstoff Nr. 1.4472.

Chemical Composition Limits

The chemical composition mandates 19.50 to 22.00 percent chromium, 9.00 to 11.00 percent nickel, 2.00 to 3.00 percent molybdenum, 2.00 to 4.25 percent manganese, 0.25 to 0.50 percent nitrogen, and 0.25 to 0.80 percent niobium. Strict maximum impurity limits require no more than 0.030 percent carbon, 0.75 percent silicon, 0.025 percent phosphorus, 0.010 percent sulfur, and 0.25 percent copper, with iron providing the balance.

Physical Properties

ASTM F1586 steel features a density of 7.88 grams per cubic centimeter (0.285 pounds per cubic inch) and a tension modulus of elasticity of 200 gigapascals. The alloy delivers a Pitting Resistance Equivalent Number between 33.0 and 38.0. Due to its stable, nitrogen-stabilized austenitic matrix, it maintains a magnetic permeability below 1.005, remaining non-magnetic even after substantial cold deformation.

Mechanical Properties

Mechanical requirements vary depending on whether the bar is supplied in the solution-annealed state or cold-worked condition.

In the solution-annealed condition, round bars mandate a minimum tensile strength of 740 megapascals (107 ksi), a minimum 0.2 percent yield strength of 430 megapascals (62 ksi), a minimum elongation of 35 percent, and a typical hardness between 200 and 250 Brinell.

In the cold-worked high-strength condition, minimum tensile strength increases to 1000 megapascals (145 ksi), minimum 0.2 percent yield strength increases to 750 megapascals (109 ksi), elongation ranges from 10 to 15 percent, and hardness reaches 30 to 38 Rockwell C.