X2CrNiMo17-12-2

Overview

Designation system

EN symbolic steel name and European steel number

Product forms

Hot- and cold-rolled sheet and strip, Hot-rolled plate, Semi-finished products, Bars and rods, Wire, Sections, Bright products, Tubes, forgings, fittings and pressure products when ordered to their respective product standards

Condition

Solution annealed, Descaled or pickled mill finishes, Cold-rolled and annealed finishes, Cold-worked strength conditions where permitted by the applicable product standard

Density

8 kg/dm³ (Reference value at approximately 20 °C; equivalent to about 8,000 kg/m³.)

How the designation and standards work

The symbolic name describes a highly alloyed steel with approximately 0.02% carbon, 17% chromium, 12% nickel and 2% molybdenum. The steel number 1.4404 is the more reliable identifier for procurement and certification. The familiar name 316L comes from the North American designation system and should be treated as a counterpart rather than as the governing EN designation.

A certificate showing only “1.4404” does not establish suitability for pressure service, structural use, hygienic service or a particular corrosion environment. The order must identify the applicable product standard and edition.

Composition and metallurgical significance

The current EN composition range extends molybdenum to 3.00%. Historical EN 10088 editions and many older data sheets show 2.00–2.50% Mo; the standard edition therefore matters when reviewing legacy specifications. EN 10088-3 permits sulfur up to 0.030% for this long-product grade and allows controlled sulfur ranges to favor machinability, weldability or polishability. Sulfur control should be stated when surface finish, orbital welding, corrosion performance or machining behavior is important.

Mechanical properties depend on product form

Austenitic stainless steels have no sharp yield point, so design and acceptance commonly use 0.2% or 1.0% proof strength. Cold work can raise proof and tensile strength markedly while reducing ductility. A strength value from cold-rolled sheet, bright bar, pressure plate or tube must not be transferred to another product form without checking its governing specification.

Corrosion behavior and service limitations

Compared with 1.4307/304L, 1.4404 has distinctly better resistance to pitting and crevice corrosion because of its molybdenum addition. This makes it a common choice for food, pharmaceutical, chemical-processing, pulp and paper, wastewater and exterior applications where 304L provides insufficient margin. Performance still depends strongly on chloride concentration, temperature, pH, oxidizing conditions, deposits, crevice geometry, surface finish and cleaning practice.

“Marine grade” is a commercial description, not a guarantee of suitability for seawater immersion, splash zones, swimming-pool atmospheres or concentrated chloride process streams. More highly alloyed austenitic or duplex grades may be necessary.

Welding and restoration of the stainless surface

1.4404 is readily welded by the usual arc and resistance processes. The low carbon level minimizes sensitization in the heat-affected zone, so ordinary welded fabrication generally does not require post-weld solution annealing. Distortion can nevertheless be significant because austenitic stainless steel combines relatively high thermal expansion with low thermal conductivity.

Heat tint is not merely cosmetic: oxide formation leaves a chromium-depleted layer beneath the colored scale and lowers localized-corrosion resistance. Corrosion-critical welds should be adequately shielded, including the root, and then cleaned by an appropriate combination of mechanical treatment, pickling and passivation. Carbon-steel tooling, grinding dust and handling contamination must be excluded or removed. Smooth weld profiles and elimination of crevices are particularly important in hygienic and chloride-bearing service.

Forming, machining and heat treatment

In the solution-annealed condition the grade is generally described as non-magnetizable, but a measurable magnetic response can result from cold-work-induced martensite or weld-metal ferrite. Applications requiring tightly controlled permeability need a specific limit, test method, product route and post-fabrication condition; the name 1.4404 alone is insufficient.

Specification and purchasing controls

Dual certification as 1.4401/1.4404 or 316/316L is common commercially, but it is valid only when the heat and product satisfy both applicable specifications and all mechanical requirements. It does not mean that the designations have become identical. For pressure equipment, use the applicable pressure-material standard—such as EN 10028-7 for flat products, EN 10216-5 or EN 10217-7 for tubes, EN 10272 for bars, EN 10222-5 for forgings or EN 10253-3 for fittings—and confirm project and regulatory requirements.

Related designations

A related designation or cross-standard counterpart is not a declaration of equivalence; confirm the standard, product form and condition before substituting.