SUS430 is a low-cost, easy-to-process stainless steel that can be widely used in various products. There are several other types of stainless steel, such as SUS304 and SUS314, each with its characteristics. Since they each have their characteristics in terms of cost, corrosion resistance, strength, and hardness, it is necessary to understand their advantages and disadvantages and then choose the right material. This article will introduce the characteristics, advantages, and disadvantages of SUS430 and the differences from other materials.
What is SUS430?
SUS can be roughly divided into 200 series, 300 series, and 400 series. Depending on the hundredth digit, the types of elements contained in the material are also different. 200 series SUS refers to austenitic stainless steel, containing chromium, nickel, and manganese. 300 series SUS is austenitic stainless steel, containing chromium and nickel. 400 series SUS includes ferritic and martensitic stainless steel. SUS430 refers to ferritic stainless steel containing 18% chromium, a representative material in the 400 series.
Although SUS430 has poor corrosion resistance among stainless steels because it does not contain nickel, it is widely used in various products due to its excellent processability and low cost. In addition, SUS430 also has the characteristics of strong magnetism, so it is often used in products that use magnetism. There are detailed standards for the surface treatment of stainless steel. The main surface treatments of SUS430 materials are as follows. The surface treatment method can be selected according to the specific application.
- SUS430-No.1: No.1 has a whitish surface and is matte. Heat treatment is required after hot rolling.
- SUS430-2B: 2B is a common surface treatment. Many SUS430 products sold on the market belong to 2B. Its surface is smooth and has a certain glossiness.
- SUS430-HL: HL means sanding treatment, and the surface appearance is continuous grinding grain, like straight hair, beautiful and neat. This material is widely used in building materials.
- SUS430-BA: BA means mirror gloss treatment. This material is mostly used in automotive parts, home appliances, decorations, etc.
Characteristics of SUS430 Stainless Steel
Stainless steel is lighter than steel, has moderate strength, and is not as soft as aluminum, so it is an easy-to-use metal. It is a high-performance material that is not easy to rust, has corrosion resistance, and has low thermal conductivity. Stainless steel is an easy-to-use and good-performing material. However, different types of stainless steel have different characteristics and uses. Here, the characteristics of SUS430 are explained from both advantages and disadvantages.
Advantages of SUS430 Stainless Steel
Compared with stainless steel, SUS430 has a lower thermal expansion coefficient, so thermal deformation is smaller. In addition, this material is not prone to stress corrosion cracking. SUS430 has the advantage of low cost. The reason for the low cost is that it does not contain nickel. Nickel is a rare metal and is a high-cost material. Nickel can improve the strength and toughness of stainless steel, such as SUS304. Improving strength is its advantage, but it also makes the corresponding material more difficult to cut. SUS430 does not contain nickel, so among stainless steels, SUS430 has good machinability and is easy to process. In addition, austenitic stainless steel does not undergo work hardening.
Disadvantages of SUS430 Stainless Steel
SUS430 may experience “475℃ embrittlement” when subjected to high temperatures such as during welding, so care must be taken. 475℃ embrittlement is a phenomenon that occurs in ferritic stainless steel. When heated to around 475℃, while the hardness increases, the ductility and toughness decrease, and it becomes brittle and fragile when subjected to impact and other factors.
The solution to 475℃ embrittlement is to control the temperature during welding. Adjust the temperature to ensure that the material does not heat up too high. Another method is to heat treat the brittle material at a temperature of 600-800℃ to eliminate the embrittlement.
Stainless steel is a metal with excellent corrosion resistance. However, by comparison, it can be found that SUS430 is not as corrosion-resistant as SUS304 and SUS316 containing nickel. In addition, it cannot be hardened by quenching, so it is not recommended for use in parts that are subjected to particularly high loads.
Uses of SUS430 Stainless Steel
SUS430 is suitable for indoor use. For outdoor environments, SUS304, which has better corrosion resistance, is often used. The main applications of SUS430 are as follows.
Kitchen sinks, kitchen equipment, and other water-using parts: SUS430 is used in a large number of products in household water-using parts because it is low-cost and easy to process. For example, kitchen sinks, taps, etc.
Stainless steel is not easy to rust, so it is often used in products that come into contact with water.
Washing machines: Washing machines also come into contact with water and need to be corrosion-resistant. Therefore, SUS430 materials, which are low-priced and easy to process, are also used.
- Automobiles: Stainless steel materials are widely used in automobiles. For example, automobile exhaust pipes, fuel injectors, and precision parts such as fixing parts are also made of SUS430.
- Kitchen gadgets: Cooking utensils such as pots and kettles are also made of SUS430. In addition, tableware such as spoons, forks, and knives are also made of SUS430.
- Building-related: Metal parts used to fix building structures are also made of SUS430. For example, you may have seen L-shaped fixings in wooden house structures.
In addition, building interiors are also made of SUS430.
Differences between SUS430 and Other Stainless Steel Materials
The following is an introduction to the differences between SUS430 and other stainless steels and steel.
Differences from SUS304
Nickel (Ni) in SUS304 has the effect of increasing the toughness of the material. The increase in toughness makes it less likely to break and improves the tensile strength. Therefore, compared with SUS430, SUS304 has the characteristics of high strength and good ductility and is a material that is impact-resistant and not easy to break. In terms of corrosion resistance, SUS304 is also higher than SUS430. Both stainless steels contain chromium, which can form a passive film on the metal surface to make it resistant to oxidation, but SUS304 contains nickel in addition to chromium, which can form a more stable non-dynamic film and further improve corrosion resistance. SUS304 is recommended for use outdoors or in other harsh environments.
Differences from Martensitic Materials
The 400 series stainless steel contains martensitic. The martensitic 400 series contains about 13% chromium, which is lower than SUS430. Martensitic stainless steels include SUS403, 410, 420, etc. SUS430 is ferritic stainless steel and cannot be quenched, but martensitic stainless steel can be quenched to increase the hardness of the material. Because it has the effect of preventing cracking and wear, it can be used for parts that will have friction, such as tools, knives, and rotating shafts. In addition, martensitic stainless steel is cheaper than SUS304 in terms of cost. However, both SUS430 and SUS304 are superior to martensitic stainless steel in terms of corrosion resistance.
Differences from Steel
SUS430 does not contain nickel and is a material with low strength among stainless steel. However, it has higher tensile strength and hardness than steel. SUS430 contains chromium and has the property of not being able to conduct heat easily, and its thermal conductivity is lower than that of steel.
Due to this characteristic, SUS430 is often used for tableware and stainless steel water bottles that require heat preservation effects. SUS430 is a stainless steel material that is easy to cut and bend. In addition, it is suitable for welding processes because of its small thermal deformation. However, it is not as good as steel in terms of weldability and machinability. In addition, unlike SUS430, which is a ferritic material, steel can be hardened by quenching.
Comparison of Thermal Conductivity, Cutting Performance, Corrosion Resistance, and Magnetism
The properties of SUS430, SUS304, SUS403, and steel are compared as follows.
| SUS430 | SUS304 | SUS403 | Steel | |
|---|---|---|---|---|
| Thermal Conductivity [W/(m・K)] | 27.0 | Column 3 Value | Column 4 Value | Column 5 Value |
| Machinability Index | 50 | 35 | 50 | 50 |
| Corrosion Resistance | ○ | ◎ | △ | × |
| Magnetic Properties | √ | × | × | √ |
In terms of thermal conductivity, austenitic SUS304 is significantly lower, while SUS430 and SUS403 are not much different. On the other hand, the thermal conductivity of SUS430 is lower than that of steel. In terms of machinability, stainless steel materials such as SUS430 are classified as difficult-to-cut materials. The higher the machinability index, the easier the material is to cut, and the lower the index, the more difficult the material is to cut. The data shows that SUS430 is an easy-to-cut material compared to SUS304.
Some SUS materials such as SUS303 are called easy-to-cut materials, so if the required cutting volume is large, it is best to choose such materials. In terms of corrosion resistance, the order from high to low is SUS304, SUS430, SUS403, and steel. This is only the comparison order of the materials listed here, but even the worst SUS403 has much higher corrosion resistance than steel.
However, this does not mean that SUS403 has low corrosion resistance. Although stainless steel gives the impression that it is non-magnetic, in fact only austenitic stainless steel is non-magnetic. Therefore, both SUS430 and SUS403 have magnetism and can be attracted by magnets.