I. SUS304 stainless steel – 0Cr18Ni9 stainless steel material
As a kind of fundamental austenitic steel, it has excellent corrosion resistance, heat resistance, low temperature resistance and mechanical properties. After heat treatment, it does not harden and almost lacks magnetism.
Features and practical applications:
| Difference | SUS304 | SUS304L |
| Characteristics | – Austenitic steel is the most used type of base metal; – Provides excellent resistance to corrosion and heat; – Provides superior resistance to low temperatures and mechanical performance; – Consists of a single-phase austenitic structure, without hardening effect due to heat treatment. |
-Compared to 304, it has excellent corrosion resistance. |
| Use | – Cutlery, exterior materials, construction materials, automobile parts; – Medical devices, chemistry, food processing, fiber industry; – Ship components |
-Equipment for chemical, coal and petroleum industries with high anti-crystalline corrosion requirements; -Construction materials, heat-resistant parts and components that are difficult to heat treat. |
Chemical Composition: (Unit:% by weight)
| Specification | W | Yes | Mn | P | s | Cr | No |
| TYPE 304 |
≤0.08 | ≤1.00 | ≤2.00 | ≤0.045 | ≤0.030 | ≤18.0-20.0 | ≤8.0-10.5 |
| TYPE 304L |
≤0.030 | ≤1.00 | ≤2.00 | ≤0.045 | ≤0.030 | ≤18.0-20.0 | ≤8.0-10.5 |
Mechanical Performance:
| Specification | YS（Mpa） | TS（Mpa） | EL（%） | Hv |
| TYPE 304 |
≥205 | ≥520 | ≥40 | ≤200 |
| TYPE 304L |
≥175 | ≥480 | ≥40 | ≤200 |
II. SUS 430 stainless steel
1. Overview
Composed of 17% Cr, it exists in mixed phase (α+γ) at high temperatures, and is a single-phase CCC structure below 1000°C. This ferritic stainless steel is widely used.
2. Features
1) Excellent deep drawing performance, similar to 304 steel.
2) Strong resistance to oxidative acids, also has certain corrosion resistance in alkaline solutions, most organic and inorganic acids. It has greater resistance to stress corrosion cracking than 304 steel.
3) The thermal expansion coefficient is lower than that of 304 steel, with high oxidation resistance, suitable for heat-resistant equipment.
4) Cold rolled products have good surface gloss and aesthetic appeal.
5) Compared to 304 steel, it is more affordable and serves as an effective alternative to 304 steel.
3. Applications
Mainly used for high polish decorative purposes in mild atmospheres, such as gas stove surfaces, household appliance parts, tableware, building interior decorations, wash basins, washing machine drums, etc.
4. Chemical Composition (JIS G 4305-2005) (% by weight)
| Chemical composition | W | Yes | Mn | P | s | Cr |
| Standard | £0.12 | £0.75 | £1.00 | £0.040 | £0.030 | 4pm~6pm |
| In general | 0.040 | 0:30 | 0.45 | 0.020 | 0.004 | 4:30 p.m. |
5. Performance (JIS G 4305-2005)
| Differentiation | Mechanical properties | Machinability | |||||
| Yes (Mpa) | Ts (Mpa) | El (%) | Hv | CCV | LDR | Er（mm） | |
| Standard | ≥ 205 | ≥ 450 | ≥ 22 | ≤ 200 | – | – | – |
| In general | 330 | 505 | 27 | 155 | 28.0 | 1.98 | 8.7 |
6 . Physical properties
| Density (g/ cm3 ) |
Magnetism | Resistance (10 6 .W.cm) |
Specific heat capacity 25℃ (J/kg.℃) |
Thermal conductivity 100°C (L/m. ℃) |
Thermal expansion coefficient 20~100°C (10 6 /℃) |
Young's Modulus 20°C (GPa) |
| 7.70 | With | 53.6 | 460 | 26.0 | 10.4 | 219 |
7. Heat treatment
- Melting point: 1425~1510°C;
- Annealing: 780~850°C.
8. Conditions of use
Annealed state: NO.1, 2D, 2B, N0.4, HL, BA, Mirror, along with various other surface treatment states.
9. Precautions for use
- Compared to 304, it has lower ductility and weldability;
- Like ferritic stainless steel, it has lower resistance and less hardening capacity, which must be considered in the selection;
- After stretch forming, surface grooves may occur in the rolling direction, which can significantly complicate polishing tasks.
III. Composition Comparison Table of 430 and 304 Stainless Steel
430 stainless steel is an American standard stainless steel material.
It is a low-carbon, high-chromium ferritic steel and belongs to one of the 400 series stainless steels.
304 stainless steel is also an American standard stainless steel material, which is chromium-nickel austenitic steel and is a common steel of 300 series stainless steel.
According to the American standard specification ASTM A240/A240M-15a for chromium and nickel-chromium stainless steel plates, sheets and strips for pressure vessels and general applications, the carbon content of 430 stainless steel should be less than 0. 12%, the chromium content should be between 16-18%, and the nickel content should be less than 0.75%.
The difference between 430 and 304 stainless steel is mainly in the nickel content.
See the chemical composition comparison table of 430 and 304 stainless steels to know the difference in element content between the two materials:
Differences in chemical composition between 430 and 304 stainless steel
| UN | Note | W | Mn | P | s | Yes | Cr | No |
| S43000 | 430 | 0.12 | 1.00 | 0.04 | 0.03 | 1 | 16-18 | 0.75 |
| S30400 | 304 | 0.07 | 2:00 | 0.045 | 0.03 | 0.751 | 7.5-19.5 | 8.0-10.5 |
Observation:
- 1. Data source: American standard ASTM A240M-15a;
- 2. The data unit is percentage, that is, “%”;
- 3. Except for the indicated range, the components listed in this table are the maximum values.
4. What is the difference between 430 and 304 stainless steel?
430 stainless steel is a ferritic stainless steel, which can be slightly strengthened by cold working, but its low temperature toughness is low and it generally cannot be hardened by heat treatment.
304 stainless steel has good plasticity and toughness. Deformation at room temperature or a slightly higher temperature will increase strength and reduce elongation.
Annealed austenitic stainless steel (such as 304 stainless steel) maintains high impact resistance.
Even at cryogenic temperatures, this property is combined with its strength and low-temperature processability to allow liquid natural gas to be transported or used in other cryogenic temperature environments.
Yield strength, tensile strength, elongation and hardness are four parameters to measure the mechanical properties of stainless steel materials.
Through comparison, we can see which is better: tensile strength, elongation and hardness.
430 and 304 stainless steel are quite different.
See the comparison table of mechanical properties of 304 and 430 stainless steel for details:
| Note | Yield Strength | Tensile strength | Stretch by 2 in. Or 50 mm, minimum |
Toughness max. |
|
| Unit | MPa | MPa | % | Brinell | Rockwell |
| 430 | 205 | 450 | 22 | 183 | 89 HRBW |
| 304 | 205 | 515 | 40 | 201 | 92 HRBW |
Data Source: ASTM Specification A240/A240M-15a for Chromium Nickel Chromium Stainless Steel Plates, Sheets, and Strips for Pressure Vessels and General Applications
V. Related data
General Properties of 430 Stainless Steel
430 stainless steel is a low C ferritic stainless steel.
Its corrosion resistance in a mildly corrosive environment or atmosphere is similar to some stainless steels containing Ni (nickel element) and has resistance to oxidation at high temperatures.
430 steel has ductility, is not easy to harden, and can be formed by many forming methods, low-tensile bending and the most commonly used drawing and bending processes.
430 stainless steel structure
When the temperature is lower than about 1650 ℉ (about 899 ℃), these alloys are ferrites with irregular spherical carbide diffusion.
When heated above 1650°F, a small amount of austenite will form at grain boundaries and in the grains.
The transformation of these austenites into martensite or ferrite and carbide depends on the cooling rate.
Martensite can be found in the welding zone and heat-affected zone of the base metal, which will be transformed into ferrite and carbide after annealing.
430 Stainless Steel Formation and Conditions
430 stainless steel can be processed into plates, strips, wires, extrusions, seamless tubes, forged billets and ingots.
When these alloys are processed into strips and sheets, they can have a variety of surface finishes (non-oriented pickling surface, highly oriented polishing surface, bright annealed mirror products).
430 Stainless Steel Applications
430 stainless steel can be used for various indoor and outdoor decorations. In these scenes, corrosion resistance is much more important than toughness.
Typical uses include sink and edge, home appliance decoration, top and bottom covers, etc.
