GRADE 430 STAINLESS STEEL (UNS S43000 / EN 1.4016) — TECHNICAL DATASHEET AND METALLURGICAL ASSESSMENT
Grade 430 stainless steel is a low-carbon, non-hardenable, plain chromium ferritic stainless steel that represents one of the most widely utilized alloys within the 400-series family. Metallurgically, the alloy is characterized by a stable body-centered cubic (BCC) crystal structure, which it maintains from room temperature up to its melting point. Because of this stable ferritic phase, the alloy does not undergo martensitic transformation during conventional heat treatment and can be increased in strength only moderately through cold working.
The alloy typically contains between 16.0% and 18.0% chromium with negligible nickel additions. This nickel-free composition provides a notable cost advantage over nickel-bearing austenitic grades like Grade 304, protecting manufacturers from price volatility in the global nickel market. The BCC matrix ensures the alloy is strongly ferromagnetic in all tempers, making it ideal for applications requiring high magnetic flux permeability or magnetic attraction.
■ International Standards and Designations
Grade 430 is covered under several major global specifications across various product forms, including plates, sheets, strips, wire, and hot- or cold-finished bars.
| Country / Standardizing Body | Standard Reference | Designation / Grade |
|---|---|---|
| Unified Numbering System (USA) | UNS S43000 | UNS S43000 |
| American Iron and Steel Institute (USA) | AISI 430 | Type 430 / 430 |
| Aerospace Material Specifications (USA) | AMS 5503 | 430 |
| European Standards (Europe) | EN 10088-2 / EN 10088-3 | 1.4016 / X6Cr17 |
| Japanese Industrial Standards (Japan) | JIS G4304 / JIS G4305 | SUS 430 |
| British Standards (UK) | BS 1449 / BS EN 10088 | 430S17 |
| French Standards (France) | AFNOR | Z8C-17 / Z8C17 |
■ Chemical Composition Specifications (wt%)
The chemical boundaries are structured to control formability, scaling resistance, and passivation kinetics. Stricter limits under European standards serve explicit microstructural safety goals.
| Chemical Element | ASTM A240 / UNS S43000 | EN 10088-2 / EN 1.4016 | JIS G4305 / SUS430 |
|---|---|---|---|
| Chromium (Cr) | 16.00 - 18.00 | 16.00 - 18.00 | 16.00 - 18.00 |
| Carbon (C) max | 0.12 | 0.08 | 0.12 |
| Manganese (Mn) max | 1.00 | 1.00 | 1.00 |
| Silicon (Si) max | 1.00 | 1.00 | 0.75 |
| Phosphorus (P) max | 0.040 | 0.040 | 0.040 |
| Sulfur (S) max | 0.030 | 0.015 | 0.030 |
| Nickel (Ni) max | 0.75 | — | 0.60 |
| Nitrogen (N) max | — | 0.030 | 0.030 |
| Iron (Fe) | Balance | Balance | Balance |
■ Proprietary Datasheet Download
For materials engineers, manufacturing detailers, and purchasing managers requiring deep texturing profiles, complete life-assessment logs, and advanced formability constraints, the proprietary datasheet must be accessed.
Grade 430 Stainless Steel — Full Mechanical Sizing & Deep Drawing Parameters
Contains empirical logs for finite element analysis, texture banding randomizing steps, and certified weld integrity limits. Corporate credentials required.
⬇ DOWNLOAD DATASHEET■ Mechanical Properties (Ambient and High Temperature)
Grade 430 exhibits low work-hardening rates and moderate ductility, performing similarly to mild low-carbon steels. Yield targets for flat-rolled products are detailed below:
| Specification & Product Form | Tensile Strength, Rm | 0.2% Yield Strength, Rp0.2 | Elongation (%) | Hardness Limits (max) |
|---|---|---|---|---|
| ASTM A240 Plate/Sheet/Strip | ≥ 450 MPa (≥ 65 ksi) | ≥ 205 MPa (≥ 30 ksi) | ≥ 22% | 183 HBW / 89 HRB |
| EN 10088-2 Sheet (≤ 8 mm) | 450 - 600 MPa | ≥ 260 MPa (transverse) | ≥ 20% | 200 HBW / 200 HV |
| EN 10088-2 Plate (8 - 13.5 mm) | 450 - 600 MPa | ≥ 240 MPa | ≥ 18% | 200 HBW / 200 HV |
| EN 10088-2 Plate (13.5 - 25 mm) | 430 - 630 MPa | ≥ 240 MPa | ≥ 20% | 200 HBW / 200 HV |
| JIS G4305 Cold-Rolled Sheet | ≥ 450 MPa | ≥ 205 MPa | ≥ 22% | 183 HBW / 88 HRB / 200 HV |
| Annealed Foil/Strip (Typical) | 517 MPa (75 ksi) | 310 MPa (45 ksi) | 30% | 85 HRB |
| Cold-Rolled Foil/Strip (Typical) | 1000 MPa (145 ksi) | 930 MPa (135 ksi) | 1% | — |
For long drawn products, light bars, and cold-drawn spring wires, mechanical attributes track dimensional diameter parameters:
| Product Form & Sizing (EN Limits) | Tensile Strength, Rm | 0.2% Yield Strength, Rp0.2 | Elongation, A (%) min |
|---|---|---|---|
| Drawn Light Bars (≤ 10 mm) | 500 - 750 MPa | ≥ 320 MPa | 8% |
| Drawn Light Bars (10 - 16 mm) | 480 - 750 MPa | ≥ 300 MPa | 8% |
| Drawn Light Bars (16 - 63 mm) | 400 - 700 MPa | ≥ 240 MPa | 15% |
| Spring Strip (+C700 / +C850 condition) | 700 - 850 MPa / 850 - 1000 MPa | — | 2% / 1% |
| Drawn Wire (1.00 - 3.00 mm, +2D) | < 800 MPa | — | — |
■ ASME SA240 Code Sizing & High-Temperature Strengths
In pressure-retaining designs under ASME Section VIII Division 1, maximum allowable design stress thresholds ($S$) degrade as temperature prompts microstructural relaxation. Short-time tensile strengths and 10,000-hour creep limits are indexed below:
| Service Temperature | ASME Allowable Stress (SA240) | Short-Time Tensile Strength | Creep Strength (1% over 10,000 h) |
|---|---|---|---|
| 100°C / 212°F | 140 MPa (20.3 ksi) | — | — |
| 200°C / 392°F | 130 MPa (18.8 ksi) | — | — |
| 300°C / 572°F | 120 MPa (17.4 ksi) | 450 MPa (65.2 ksi) | — |
| 400°C / 752°F | 110 MPa (16.0 ksi) | 430 MPa (62.3 ksi) | — |
| 550°C / 1022°F | — | 220 MPa (31.9 ksi) | 50 MPa (7.25 ksi) |
| 650°C / 1202°F | — | 120 MPa (17.4 ksi) | 15 MPa (2.18 ksi) |
| 750°C / 1382°F | — | 50 MPa (7.25 ksi) | 3 MPa (0.44 ksi) |
■ Physical, Thermal, and Electromagnetic Properties
The nickel-free chemistry yields low density and higher thermal conductivity than austenitic alloys, reducing localized thermal strains. Dynamic elastic constants softer continuously with heat:
| Physical Constants (at 20°C Base) | Metric Units | Imperial Units |
|---|---|---|
| Density (Annealed state) | 7.70 - 7.75 g/cm³ | 0.278 - 0.280 lb/in³ |
| Melting Range Boundaries | 1425 - 1510 °C | 2595 - 2750 °F |
| Solidus / Liquidus Points | Solidus: 1425°C / Liquidus: 1510°C | Solidus: 2600°F / Liquidus: 2750°F |
| Bulk Modulus / Shear Modulus | 144 - 159 GPa / 77 GPa | 20.9 × 10⁶ - 23.1 × 10⁶ psi / 11.2 × 10⁶ psi |
| Poisson's Ratio (ν) | 0.27 - 0.28 | 0.27 - 0.28 |
| Specific Heat Capacity (0 - 100°C) | 460 J/kg·K | 0.110 Btu/lb·°F |
| Thermal Conductivity (at 100°C / 500°C) | 24.9 - 26.1 W/m·K / 26.0 - 26.3 W/m·K | 166 - 181 Btu·in/hr·ft²·°F / 180 - 182 Btu·in/hr·ft²·°F |
| Electrical Resistivity (Ambient) | 600 nΩ·m | 361.0 ohm-cir-mil/ft |
| Relative Magnetic Permeability | 600 - 1100 (Typical 800) | 600 - 1100 (Typical 800) |
| Latent Heat of Fusion | 260 - 285 kJ/kg | 111.8 - 122.5 Btu/lb |
| Temperature Range Threshold | Mean Coeff. of Thermal Expansion (α) | Tension Modulus, E (GPa / Simple Mpsi) |
|---|---|---|
| 20 - 100°C / 68 - 212°F | 10.4 - 10.5 × 10⁻⁶ /°C | 200 - 220 / 29.0 - 31.9 |
| 20 - 200°C / 68 - 392°F | 11.0 × 10⁻⁶ /°C | 210 / 30.5 |
| 20 - 300°C / 68 - 572°F | 11.5 × 10⁻⁶ /°C | 205 / 29.7 |
| 20 - 400°C / 68 - 752°F | 12.0 × 10⁻⁶ /°C | 195 / 28.3 |
■ Derivative Specifications & Alternative Alloy Selection
To bypass the specific limits of Grade 430, structural designers prioritize specialized chemistry variants tailored for unique fabrication constraints.
| Fastener Grade / Sizing | UNS / EN Code | Metallurgical Modification Feature | Core Performance Selection Criteria |
|---|---|---|---|
| Grade 430 | S43000 / 1.4016 | Plain Chromium Ferritic Steel Base | Reference alloy; cost-effective, ferromagnetic, resists chloride SCC. |
| Grade 430F | S43020 / 1.4104 | Sulfur Addition (≥ 0.15% S) | Free-machining variant; MnS stringers fracture chips cleanly. Lower pitting limit. |
| Grade 434 | S43400 / 1.4113 | Molybdenum Addition (1.0% Mo) | Stabilizes passive film against pitting stringency in hot de-icing salt zones. |
| Grade 439 (430Ti) | S43035 / 1.4510 | Titanium-stabilized (Ti ≈ 0.15-0.7%) | Binds carbon as TiC, preventing HAZ sensitization without mandatory PWHT. |
| 430 LNbTi | S45090 / 1.4509 | Dual Ti & Nb Stabilization | Advanced stabilization for exhaust manifolds; restricts grain coarsening bursts. |
■ High-Temperature Fastening Torque Specifications
Type 416/430 elements are standardly requested for nuts under ASTM A194 Grade 6F rules, hardened within 225 to 271 HBW. Verified assembly dry torques are cataloged below:
| Fastener Thread Size | Threads Per Inch (TPI) | Dry Assembly Torque (Inch-Pounds) | Dry Assembly Torque (Foot-Pounds) |
|---|---|---|---|
| 1/4" | 20 | 78.8 | 6.5 |
| 5/16" | 18 | 138.0 | 11.5 |
| 3/8" | 16 | 247.0 | 20.5 |
| 1/2" | 13 | 542.0 | 45.1 |
| 5/8" | 11 | 1160.0 | 96.7 |
| 3/4" | 10 | 1582.0 | 131.8 |
| 1" | 8 | 3595.0 | 299.6 |
■ Material Engineering Controls and Operational Restrictions
- The 475°C Embrittlement Nose: Grade 430 must never be allowed to soak inside or cool slowly through the 400°C to 540°C (752°F to 1004°F) window. Prolonged operations (exceeding 100 hours) trigger spinodal micro-decomposition, segregating matrix bonds into iron-rich alpha ($\alpha$) and chromium-rich alpha-prime ($\alpha'$) phases. This ruins ductility and decreases pitting boundaries. Remediate by re-heating above 760°C and running a rapid quench.
- The Low-Temperature Cleavage Limit (DBTT): The body-centered cubic matrix imposes a sharp ductile-to-brittle transition temperature centered within 0°C and -20°C. Below these limits, Charpy impact energy absorption values fall off to ≤ 15 Joules, risking rapid cleavage fractures. Grade 430 is strictly excluded from cryogenic lines or dynamic impact-loaded systems.
- Deep-Drawing Ridging Prevention: Severe drawing parallel to the rolling path causes macroscopic surface corrugations ("roping" or "ridging") due to localized texture banding. Control by enforcing a specific slab hot-rolling max threshold of 1010–1065°C, followed by a two-stage box band anneal (954–1038°C for 1h → 788–816°C for 2h → slow furnace cool) to completely randomize grain anisotropy colonies prior to continuous processing.
- Weldment Heat-Affected Zone (HAZ) Embrittlement: Thermal cycles exceeding 1000°C drive rapid grain coarsening and trigger partial brittle martensitic transformation fields upon cooling, promoting cold cracking risks. Enforce a mandatory preheat to 150–200°C, keep heat input minimized, and run a post-weld sub-critical temper anneal at 790–815°C to restore boundary toughness. Alternatively, select stabilized Grade 439 to bypass post-weld treatments.
- Machining and Tooling Engagement: Automatic lathe parameters function optimally with HSS tools at 135–155 SFPM. Ensure tooling forces are raised by 30% to 50% relative to basic low-carbon steels. Wrenching or turning feeds must remain continuous; allowing tools to dwell or rub generates severe subsurface glazing, instantly dulling cutting edges.
- Pitting vs. Stress Corrosion Passivity: Possessing a baseline PREN ≈ 17, Grade 430 is vulnerable to halide spallation and pitting staining in marine or high-chloride atmospheres, requiring mirror-polished surfaces to eliminate crevice traps. However, the ferritic matrix offers outstanding protection against chloride-induced stress corrosion cracking (SCC), making Grade 430 structurally superior to Grade 304 for pressurized hot water tanks and static heat exchangers.