Selection summary
Overview
2101 lean duplex stainless uses chromium, manganese, and nitrogen with relatively low nickel and molybdenum to deliver high strength and useful corrosion resistance. It can compete with 304L or 316L in selected tank, structural, and process duties, but substitution requires verification of pitting, crevice, weld, low-temperature, and product-standard requirements.
This page separates standard-oriented limits from typical reference data. Purchase acceptance comes from the ordered specification and certified material test report.
Names and systems
Identity & standards
Similar designations across ASTM, EN, JIS, and other systems are not automatically interchangeable. Product form and ordered standard control chemistry, properties, dimensions, condition, and testing.
Reference chemistry
Composition
| Element | Reference range | Why it matters |
|---|---|---|
| Chromium | 21.0–22.0% | Passive-film and duplex balance |
| Nickel | 1.35–1.70% | Austenite balance |
| Manganese | 4.0–6.0% | Austenite and nitrogen support |
| Nitrogen | 0.20–0.25% | Strength, pitting resistance, and phase balance |
Concise grade-family reference only. Confirm every element limit against the current standard for the exact product ordered.
Condition matters
Reference properties
Solution-annealed flat-product reference; verify thickness and standard
Solution-annealed flat-product reference with product-form limits
Typical room-temperature engineering reference
Environment first
Corrosion behavior
Offers useful stress-corrosion cracking resistance and corrosion performance for many mild-to-moderate chloride applications.
Its pitting and crevice resistance is not automatically equal to 2205 or 2507 and must be checked for temperature, chloride, deposits, and geometry.
Temperature, concentration, deposits, crevices, stress, surface finish, cleaning, and fabrication quality can change service performance.
Service limits
Temperature & service
Duplex toughness and phase stability limit both low- and elevated-temperature use; apply the governing code and product specification.
Delivery condition
Heat treatment & condition
2101 requires product-appropriate solution annealing followed by rapid cooling to establish the intended ferrite-austenite balance.
It is not hardened by thermal treatment; uncontrolled hot work or welding can create excessive ferrite, nitrides, or other harmful phases, so heat input and interpass temperature need qualified limits.
Process route
Fabrication
Higher strength increases forming load and springback; duplex bend radii and tooling review are required.
Welding must preserve phase balance through qualified heat input, interpass temperature, filler, shielding, and cleaning.
Magnetic response: Magnetic because of its ferritic-austenitic microstructure.
Decision boundaries
Comparisons & substitution
2101 provides higher yield strength and better chloride stress-corrosion resistance than common annealed austenitic grades in many verified environments, but its pitting margin is not automatically equal to 2205.
2304 offers a different chromium-nickel balance with little molybdenum; 2205 or 2507 is reviewed as chloride, crevice, or process severity rises.
Where it is used
Applications
Ordering scope
Product forms & standards
Plate, sheet, and strip in the specified solution-annealed condition with the exact UNS designation and any ordered corrosion testing.
Pipe, tube, fittings, flanges, bar, and forgings under form-specific standards with heat treatment, weld, phase-balance, and NDE controls.
Decision support
Selection guidance
Choose this grade when
- High yield strength can reduce section and the environment fits verified lean-duplex corrosion capability.
- Nickel and molybdenum economy is useful without sacrificing the required weld and structural performance.
Review another grade when
- Severe chloride, sour, high-temperature, or crevice conditions require 2205, 2507, or another qualified alloy.
- The fabrication shop lacks duplex welding and ferrite/heat-treatment controls.
Before ordering
Procurement checklist
Name the governing product specification and edition, exact UNS designation, dimensions, tolerances, finish, and delivery or heat-treatment condition.
Require a traceable material test report and verify chemistry, mechanical tests, heat treatment, marking, and any supplementary examination against the purchase order.
State the service environment, design temperature, fabrication route, inspection plan, certification, packaging, and any regulatory or end-user approval before order release.
Traceable evidence