204Cu (UNS S20430 / 1.4597) is a manganese-enriched, low-nickel austenitic stainless steel belonging to the 200-series nickel-saving grades, originally developed by Carpenter Technology. Its core design concept uses manganese and nitrogen to partially replace nickel, with intentional copper addition to enhance formability and resistance to stress corrosion cracking. It serves as a cost-effective alternative to Type 304, outperforming conventional 201 and 202 stainless steel.
Available product forms: Stainless steel wire rod, bright drawn wire, cold finished wire, annealed soft wire, spring wire, welding wire.
Applicable Specifications:
ASTM: ASTM A313 (spring wire)
ASTM A580 / A493 (stainless steel wire and wire rod)
European Standard: EN 10088-3, Material No. 1.4597
Key characteristics: Lower work-hardening rate than 201 / 202; excellent performance for deep drawing and bending; copper improves resistance to stress corrosion cracking; non-magnetic in fully annealed condition; slight magnetism develops after heavy cold working.
2. Equivalent Grade Comparison Worldwide
| Standard System | Grade Designation | Remarks |
| US AISI / UNS | 204Cu; UNS S20430 | Original registered grade |
| EU EN Material Number | 1.4597 | Widely used European designation |
| EN Chemical Grade | X8CrMnCuNB17-8-3 | Full EN nominal grade |
| German DIN | 1.4597 | No separate old DIN grade, use material number directly |
| British BS | BS 3111 | |
| Japanese JIS | No official equivalent; market alias J204Cu (non-standard) | |
| Chinese GB/T | No officially registered national grade; commercial name: 204Cu / J204Cu | ⚠️ No unified national standard code. For foreign trade contracts, specify UNS S20430 / 1.4597 preferentially |
Important distinction: Do not confuse with regular 201 (S20100) and 202 (S20200). Distinctive feature of 204Cu: Cu content 2.0~3.5%, Ni ≤ 3.0%.
3. 204Cu 200Cu 201Cu D667 D669 Chemical Composition (wt%, Solution Annealed Condition)
| GRADE | C | Si | Mn | P | S | Cr | Ni | Cu | N |
| 204Cu | ≤0.100 | ≤2.00 | 6.50~9.00 | ≤0.04 | ≤0.030 | 15.0~18.0 | 1.50~3.00 | 2.00~4.00 | 0.10~0.30 |
| Below are other kind of 200Serious included Cu.from Chinese enterprise standard | |||||||||
| 200Cu | ≤0.080 | ≤1.00 | 10.50-12.50 | ≤0.005 | ≤0.030 | 13.0-15.0 | 1.50-2.00 | 2.00-2.50 | ≤0.25 |
| 201Cu | ≤0.080 | ≤1.00 | 8.00-10.00 | ≤0.005 | ≤0.030 | 13.0-15.0 | 4.00~5.00 | 2.00-2.50 | ≤0.25 |
| D666 | 0.05~0.10 | ≤1.00 | 12.00~13.50 | ≤0.050 | ≤0.030 | 12.5~14.5 | ≤2.00 | 1.50~2.50 | ≤0.25 |
| D667 | ≤0.080 | ≤1.00 | 11.50~14.50 | ≤0.050 | ≤0.030 | 12.5~14.5 | 0.70~2.00 | 1.80~2.50 | ≤0.25 |
| D669 | ≤0.15 | ≤1.00 | 12.50~16.00 | ≤0.050 | ≤0.030 | 10.50~12.50 | ≤2.00 | 0.40~1.20 | ≤0.25 |
4. Physical Properties (Room Temperature, Solution Annealed State)
| Parameter | Value |
| Density | 7.81 g/cm³ |
| Melting Range | 1390 ~ 1450 °C |
| Coefficient of Linear Thermal Expansion (20~100°C) | 17.1 ×10⁻⁶ /°C |
| Thermal Conductivity (20°C) | 15.0 W/(m·K) |
| Specific Heat Capacity | 496 J/(kg·K) |
| Electrical Resistivity | ~72 μΩ·cm |
| Magnetic Property | Non-magnetic after annealing; weakly magnetic after cold deformation |
5. Mechanical Properties (Wire Products, Different Delivery Conditions)
5.1 Solution Annealed Soft Condition (2D Base Raw Wire)
| Item | Specification |
| Tensile Strength (Rm) | 560 ~ 780 MPa |
| 0.2% Proof Strength (Rp0.2) | ≥245 MPa |
| Elongation (A5) | ≥40% |
| Hardness HB | ≤245 HB (HRB ≤100) |
5.2 Cold Working Hardening Reference (Cold Drawn Wire)
| Cold Reduction Ratio | Tensile Strength (MPa) | Approximate Elongation |
| 20% | 820 ~ 900 | ≥32% |
| 40% | 1050 ~ 1150 | ≥22% |
| 50% | 1180 ~ 1280 | ≥16% |
| 60% | 1350 ~ 1450 | ≥10% |
Custom bright finished wire and high-strength spring wire with specified tensile grades are available. Suitable for bending, heading, weaving and stamping applications.
6. Machinability, Heat Treatment & Corrosion Resistance
6.1 Heat Treatment Features
✅ Not hardenable by quenching (austenitic stainless steel; strength improvement only via cold working)
Solution annealing temperature: 1010 ~ 1120 °C, rapid air cooling or water quenching
Purposes: Softening, relieving residual stress, restoring ductility
Not age-hardenable; maximum continuous service temperature recommended ≤450 °C
6.2 Forming Performance
Advantages: Lower work-hardening rate than 201, comparable to 304. Ideal for deep drawing, continuous bending, wire weaving, heading for screws and rivets.
Machining: High ductility leads to long chips; low cutting speed and sufficient lubrication are recommended.
6.3 Weldability
Suitable for TIG welding and plasma welding. Matching 200-series welding consumables are recommended. ⚠️ Higher sensitization risk than 304 under sustained high temperature; not preferred for long-term high-temperature service. Welds are susceptible to intergranular corrosion; solution annealing after welding is suggested for corrosive service environments.
6.4 Corrosion Resistance (Critical for Material Selection)
Atmospheric exposure, fresh water and indoor humid environments: Good performance, close to 304, much better than 201
Weak organic acids and detergent environments: Benefit from copper alloying
❌ Not recommended for seawater, long-term immersion in high-chloride media or concentrated acids & alkalis (no molybdenum; inferior pitting resistance vs 304, far lower than 316)
Resistance to chloride-induced stress corrosion cracking (SCC): Significantly superior to copper-free 201 / 202
Approximate Pitting Resistance Equivalent Number (PREN): 22 ~ 26 (lower than 304 PREN ≈28)
7. Material Comparison: 204Cu vs 201 vs 304
| Item | 204Cu | 201 (S20100) | 304 (1.4301) |
| Nickel Content | 1.5~3.0% | 3.5~5.5% | 8~10% |
| Copper Content | 2.0~3.5% | Trace | Trace |
| Deep Drawability | ★★★★ | ★★☆ | ★★★★★ |
| Work-hardening Rate | Low | Very High | Medium |
| General Atmospheric Corrosion Resistance | Good | Fair | Excellent |
| Raw Material Cost | Medium (201 ＜ 204Cu ＜ 304) | Lowest | Highest |
8. Typical Applications of 204Cu Stainless Steel Wire
Fasteners & Wire Products (Main Application Field)
Rivets, screws, self-tapping screws, hose clamps, retaining springs, circlips, chains
Woven metal mesh, filter screens, decorative wire mesh
Hardware & Household Products
Kitchen hardware accessories, stamping parts, wire brackets, decorative wire components
Automotive & General Engineering
Light-load springs, wiring harness fixtures, pipe fittings, formed stamped components for interior parts
Other Fields
Braided shielding wire, craft wire, wire formed daily hardware
Selection Tip: Choose 204Cu when you need better formability than 201 while controlling cost, and corrosion requirement is not as strict as 304. Not applicable for marine and heavy chloride service conditions.
