Selection summary
Overview
2304 is a chromium-nickel-nitrogen duplex stainless steel with little molybdenum, providing roughly twice the yield strength of common annealed austenitic grades and useful stress-corrosion resistance. It is selected for verified structural, storage, water, and process environments, while pitting demand, weld procedure, phase balance, impact requirements, and product form control the decision.
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 | 21.5–24.5% | Passive-film and duplex balance |
| Nickel | 3.0–5.5% | Austenite balance and toughness |
| Molybdenum | 0.05–0.60% | Controlled pitting-resistance contribution |
| Nitrogen | 0.05–0.20% | 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 product and thickness
Solution-annealed flat-product reference under the ordered standard
Typical room-temperature engineering reference
Environment first
Corrosion behavior
Provides good general corrosion and chloride stress-corrosion resistance in many moderate environments.
Lower molybdenum means less pitting and crevice margin than 2205 in aggressive chloride conditions.
Temperature, concentration, deposits, crevices, stress, surface finish, cleaning, and fabrication quality can change service performance.
Service limits
Temperature & service
Use at low or elevated temperature is limited by duplex toughness and phase stability; follow the governing design code.
Delivery condition
Heat treatment & condition
2304 is solution annealed and rapidly cooled under the applicable product standard to restore duplex phase balance and corrosion performance.
Thermal hardening is not used; welding and hot forming must control heat input, time at temperature, interpass temperature, cooling, and any required corrosion or ferrite testing.
Process route
Fabrication
Forming requires higher loads and greater springback allowance than annealed austenitic stainless.
Qualified welding and heat-treatment controls are required to maintain phase balance, toughness, and corrosion resistance.
Magnetic response: Magnetic because of its duplex structure.
Decision boundaries
Comparisons & substitution
2304 offers high duplex strength and useful stress-corrosion resistance with less molybdenum than 2205, so pitting and crevice limits require separate verification.
2101 emphasizes lean alloying through manganese and nitrogen, while 2205 and 2507 provide progressively greater alloy and chloride-corrosion margin with stricter fabrication demands.
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
- A high-strength duplex can reduce section in a moderate corrosion environment.
- The application needs better chloride stress-corrosion resistance than common austenitic grades but not 2205-level pitting resistance.
Review another grade when
- Pitting, crevice, seawater, or sour-service severity exceeds verified 2304 capability.
- Impact toughness, welding, or thermal exposure cannot be controlled within duplex limits.
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