AISI 430 Stainless Steel - Chemical Composition, Mechanical & Physical Properties
by AMC
Posted on January 15, 2024 at 03:57 PM
Stainless steel is a vital player in diverse industrial applications, and within this alloy family, grade 430
stands out. Belonging to the ferritic group of steels, grade AISI 430 is a non-hardenable steel with a
straight chromium composition. In this exploration, we will delve into the properties and applications of
grade AISI 430, along with its variants, shedding light on its significance in the realm of metallurgy.
AISI 430 stainless steel is well-known for its non-hardenable nature, offering a unique blend of corrosion
resistance and formability. The straight chromium content contributes to its practical mechanical properties,
making it valuable in various industrial settings.
One notable feature of AISI 430 is its applicability in certain chemical environments, owing to its
commendable resistance to nitric acid. This property opens doors for its use in diverse chemical applications,
where materials need to withstand corrosive elements.
When it comes to automation and precision machining, grade 430F steps into the spotlight. Often provided in
bar form, this variant of stainless steel is tailored for automatic screw machines. The seamless integration
of grade 430F into such machining processes showcases its versatility and suitability for applications that
demand precision and efficiency.
As we explore further, we encounter grade 434, a variant of stainless steel that shares similarities with its
predecessor, grade 430. The distinctive feature of grade 434 lies in its molybdenum-bearing composition. The
infusion of molybdenum enhances corrosion resistance, making grade 434 an attractive choice in environments
where resilience against corrosive elements is paramount.
Key Properties of AISI 430
Now, let's unveil the essential characteristics of grade 430 stainless steel, focusing on its coil, sheet, and plate forms, all of which fall under the ASTM A240/A240M standards. Understanding these properties is crucial for engineers, manufacturers, and enthusiasts alike, as it provides valuable insights into the material's behavior under different conditions.
AISI 430 & 430F Grade Specification Comparison
| Grade | UNS No | Old British | Euronorm | Swedish SS | Japanese JIS | ||
| BS | En | No | Name | ||||
| 430 | S43000 | 430S17 | 60 | 1.4016 | X8Cr17 | 2320 | SUS 430 |
| 430F | S43020 | - | - | 1.4104 | X12CrMoS17 | 2383 | SUS 430F |
AISI 430 Chemical Composition
| Type 430 Chemical Composition, % | |||||||||
| ASTM | AISI (UNS) | C, ≤ | Si, ≤ | Mn, ≤ | P, ≤ | S, ≤ | Cr | Ni, ≤ | Product |
| ASTM A240/A240M | 430 (UNS S43000) | 0.12 | 1.00 | 1.00 | 0.040 | 0.030 | 16.0-18.0 | 0.75 | Plate, Sheet, and Strip |
| ASTM A276/A276M | 0.12 | 1.00 | 1.00 | 0.040 | 0.030 | 16.0-18.0 | – | Bars and Shapes | |
AISI ASTM 430 Stainless Steel Mechanical Properties
| SS 430 Mechanical Properties | ||||||||
| Type (UNS) | Tensile strength, MPa (ksi), ≥ | Yield strength, MPa (ksi), ≥ | Elongation in 50 mm, %, ≥ | Reduction in area, %, ≥ | Brinell Hardness, ≤ | Rockwell Hardness, ≤ | Cold Bend, ≤ 25 mm (1 in.) | Product form and Condition |
| 430 (UNS S43000) | 415 (60) | 207 (30) | 20 | 45 | – | – | – | Bar, Annealed, hot-finished or cold-finished |
| 450 (65) | 205 (30) | 22 | 183 HBW | 89 HRBW | 180° | Sheet, Plate and Strip | ||
| 485 (70) | 275 (40) | 16 | 45 | – | – | – | Wire, Annealed, Cold finished | |
AISI 430 Physical Properties
| SS 430 Physical Properties | |
| Density, g/cm3 (lb/in.3) | 7.8 (0.28) |
| Melting point, °C (°F) | 1425-1510 (2600-2750) |
| Specific heat capacity, J/kg · K (Btu/lb · °F) | 460 (0.11) at 0-100 °C (32 to 212 °F) |
| Electrical resistivity, μΩ·m | 0.60 at 20 ℃ |
| 430 stainless steel magnetic permeability | 600-1100 (Approximate) |
| Elastic modulus (Modulus of elasticity), GPa (106 psi) | 200 (29.0) |
| Thermal diffusivity, mm2/s | 7.3 |
| Thermal conductivity, W/m · K (Btu/ft · h · °F) | 26.1 (15.1), at 100 ℃ (212 °F) |
| 26.3 (15.2), at 500 ℃ (932 °F) | |
| Coefficient of thermal expansion, μm/m · °C (μin./in. · °F) | 10.4 (5.8), at 0-100 ℃ (32-212 °F) |
| 11.0 (6.1), at 0-315 ℃ (32-600 °F) | |
| 11.4 (6.3), at 0-538 ℃ (32-1000 °F) | |
AISI ASTM 430 Stainless Steel Heat Treatment
For AISI ASTM 430 stainless steel, annealing is a key heat treatment step. The recommended temperature range
for annealing this steel is 705-790 °C (1300-1450 °F). Annealing involves heating the material to a specific
temperature and holding it at that temperature for a calculated duration, followed by a controlled cooling
process.
When it comes to forging AISI ASTM 430 stainless steel, precision in temperature control is once again
paramount. The typical forging temperature for SS430 ranges between 815-1120 °C (1500-2050 °F). Forging
involves shaping the material at elevated temperatures, aligning its grain structure, and enhancing its
mechanical properties.
Heat Resistance
| Maximum service temperatures, °C (°F) | ||
| AISI | Intermittent service | Continuous service |
| 430 | 870 (1600) | 815 (1500) |
Welding
Welding presents unique challenges for type 430 stainless steel (SS430) due to its lower ductility compared to
austenite types. This divergence in ductility increases the susceptibility to weld cracking, especially when a
significant amount of martensite forms during the cooling phase post-welding. To mitigate these challenges and
ensure a successful welding process, specific precautions are recommended.
Type 430 stainless steel's lower ductility makes it prone to weld cracking, a phenomenon where fractures occur
in the welded material. This is particularly crucial to address because, during the cooling phase after
welding, a substantial amount of martensite is formed. Martensite, being a harder crystalline structure,
increases the material's sensitivity to cold cracking.
Corrosion Resistance: AISI 430 Stainless Steel (SS430)
AISI 430 stainless steel (SS430) demonstrates reliable corrosion resistance, rendering it well-suited for deployment in mild atmospheres and exposure to mild oxidizing acids and organic acids. While it exhibits proficiency in these environments, it's imperative to acknowledge certain limitations. Specifically, AISI 430 is not recommended for use in sulfuric acid settings, where alternative stainless steel grades such as AISI 302 or 304 prove more resilient. In the realm of food processing, the elevated standards of hygiene necessitate the use of AISI 304 over SS430. Furthermore, for applications in marine environments, heavily polluted atmospheres, or exposure to more severe corrosives, opting for AISI 316 stainless steel or higher alloyed materials is advised. By recognizing these nuances, informed decisions can be made, ensuring optimal corrosion resistance in diverse scenarios.
Machining
The machinability of stainless steel grade 430 surpasses that of standard austenitic steels like grade 304. However, caution is warranted due to the potential for galling. Notably, lightly drawn bars prove more conducive to machining compared to bars in the annealed condition. For enhanced ease, grade 430F stands out as particularly easy to machine.
Fabrication
Stainless steel grade 430 boasts a low work hardening rate, facilitating easy bending and forming processes during fabrication. While its low ductility rate presents challenges for rigorous operations, the material exhibits capability in handling cold heading for grade 430 wire. In instances of extreme cold working, sub-critical intermediate annealing may be necessary to maintain optimal performance. The balance of machinability and fabrication flexibility positions grade 430 as a versatile choice for a range of applications.
Versatile Applications of Stainless Steel Grade 430
Stainless steel grade 430 finds diverse applications across various industries, showcasing its versatility and durability. The following are key areas where this stainless steel grade proves invaluable:
- Dishwasher Linings: Stainless steel grade 430 is employed for its corrosion resistance and formability, making it an ideal material for dishwater linings. Its robust properties ensure longevity in the demanding environment of dishwashing appliances.
- Refrigerator Cabinet Panels: The corrosion-resistant nature of grade 430 makes it well-suited for refrigerator cabinet panels. The material's ability to withstand mild atmospheres and oxidizing acids contributes to the longevity and aesthetic appeal of refrigerator components.
- Element Supports and Fasteners: In various industrial applications, including heating elements and fastening systems, grade 430 stainless steel is chosen for its machining ease and sufficient corrosion resistance. This ensures reliable support and lasting performance in diverse environments.
- Stove Trim Rings and Chimney Liners: The durability and corrosion resistance of stainless steel grade 430 make it a preferred choice for stove trim rings and chimney liners. These components endure exposure to heat and varying conditions, emphasizing the reliability of the material.
- Automotive Trim and Lashing Wires: Grade 430 finds application in the automotive industry, specifically in trim components and lashing wires. Its combination of formability and resistance to corrosion contributes to the aesthetic and functional aspects of automotive design.
Conclusion
Stainless steel grade 430 emerges as a versatile and reliable player, demonstrating a harmonious balance of properties that cater to a multitude of applications. From its commendable corrosion resistance to its machinability and fabrication flexibility, SS430 proves its mettle in dishwashers, refrigerators, automotive components, and beyond. From machining efficiency to fabrication ease, SS430 showcases its adaptability in different processing stages. The material's application spectrum spans dishwasher linings, refrigerator panels, element supports, stove trim rings, and automotive trim, underlining its diverse utility across industries.
SAE 1018 Steel
SAE 1018 mild/low carbon steel is renowned for its exceptional weldability, contributing to ease in fabrication. This steel exhibits the capability to produce a uniform and harder case, making it particularly well-regarded for carburized parts.
