Aço inoxidável 301 vs 304: a diferença explicada

301 vs 304 Stainless Steel: The Difference Explained

What is the difference between SUS301 and SUS304?

SUS304 (stainless steel):

This is the most commonly used type of stainless steel. Due to its nickel content, it has better corrosion resistance and heat resistance than chrome steel.

It also has good mechanical properties and a high hardening rate, making it ideal for use in structural supports that require resistance.

SUS304 is non-magnetic and has good resistance, but is less elastic. It is typically used in thicknesses between 0.4T to 1.0T. When used in notebook applications, it is important to specify the appropriate class to meet the design requirements. The best option is usually 3/4H. For stretching and drawing applications such as LCD brackets, 1/2H is typically recommended.

However, some companies now use SUS430 instead of SUS304 to save money.

SUS301 (stainless steel):

This type of stainless steel has a lower chromium content than SUS304, which makes it less resistant to corrosion. However, it can achieve very high tensile strength and hardness through cold working, making it suitable for a wide range of applications.

Due to its elasticity, it is commonly used in notebook applications for EMI shielding and elastic contact parts. However, it is typically used in thicknesses between 0.4T and 0.07T, and it is important to specify the appropriate grade to meet design requirements (such as elasticity and strength).

It should be noted that the direction of the metal's crystal structure in material 301 affects its hardness and brittleness, with higher grades being harder and more brittle. If not handled properly during forming, it can cause cracks in the corners and side walls.

Material properties:

SUS301: Suitable for elastic applications, with high carbon content and hardness. It is not prone to elastic fatigue, but it has low ductility and is not easily removed.

SUS304: Not suitable for elastic, low carbon and low hardness (soft) applications. SUS430: Contains more impurities, resulting in unstable hardness.

Observation:

  • If the hardness of both materials is similar, such as SUS301 3/4H and SUS304 H, although the hardness is the same, SUS304 H is more likely to suffer elastic fatigue when used in elastic products.
  • The thickness of the material affects the hardness tolerance (the thicker the material, the higher the tolerance).

SUS301

Chemical composition of SUS301:

Note SUS301
Chemical composition
(Weight%)
(W) ≤0.15
(Mn) ≤2.00
(Ni) 6:00-8:00
(Si) ≤1.00
(P) ≤0.035
(S) ≤0.030
(No.) /
(Cr) 4pm-6pm

Observation:

Heat treatment specification: Solution treatment at 1010-1150℃ followed by rapid cooling.

Metallographic structure: The microstructure is characterized by austenite.

Delivery condition: Generally delivered in the heat-treated state, with the specific type of heat treatment specified in the contract. If not specified, it will be delivered untreated.

Mechanical properties of SUS301

Note SUS301
Mechanical properties Tensile strength σb (MPa) ≥520
Yield resistance σs (Mpa) ≥205
Stretching δs (%) ≥40
Area reduction ψ(%) ≥60
Akv impact energy
(J)
/
Impact resistance value α kv
(J/ cm2 )
/
Toughness /
Blank sample size /

Hardness: ≤187HB; ≤90HRB; ≤200HVK

Note Mechanical properties
SUS304 ANN 200 max. 205 minutes 520 minutes 40 minutes
SUS304 1/2H 250 minutes 470 minutes 780 minutes 6 minutes
SUS304 3/4H 310 minutes 665 minutes 930 minutes 3 minutes
SUS304 FC 370 minutes 880 minutes 11:30 am /
SUS301 ANN 200 max. 205 minutes 520 minutes 40 minutes
SUS301 1/2H 310 minutes 510 minutes 930 minutes 40 minutes
SUS301 3/4H 310 minutes 745 minutes 11:30 am 5 minutes
SUS301 FC 430 minutes 1030min 1320 minutes 3 minutes
SUS301 EH 490 minutes 1275 minutes 1570 minutes /

SUS 301 density

SUS 301 has a density of 7.93 g/cm³.

Hardness SUS301

Material Hardness mark Hardness value
SUS301 1/4H 250 ~ above 250
SUS301 1/2H 300 ~ above 310
SUS301 3/4H 360 ~ above 370
SUS301 H 400~ above 430
SUS301 EH Above 490

SUS304

“SUS” is a general term for Japanese steel grades. SUS304 is a Japanese JIS standard stainless steel, which corresponds to China's 0Cr18Ni9 and USA's 304.

Properties: It has good corrosion resistance, heat resistance, low temperature resistance and mechanical properties. It has good hot working properties such as stamping and bending, and does not harden during heat treatment. It's not magnetic.

Uses: Household utensils, cabinets, internal piping, water heaters, boilers, bathtubs, automotive parts, medical devices, building materials, chemicals, food industry, agriculture and ship components.

SUS304 Properties

Note SUS304
Mechanical properties Tensile strength σb (MPa) ≥520
Yield strength σs (MPa) ≥205
Stretching δ5 (%) ≥40
Area reduction ψ(%) ≥60
Impactful energy Akv (J) /
Impact resistance Value/αkv
(J/ cm2 )
/
Toughness /
Blank sample size /

Hardness: ≤187HB; ≤90HRB; ≤200HV

SUS304 Density

SUS 304 has a density of 7.85 g/cm³.

SUS304 stainless steel composition

Note SUS304
Chemical composition (WT%) (W) ≤0.07
(Mn) ≤2.00
(Ni) 8:00-11:00
(Si) ≤1.00
(P) ≤0.035
(S) ≤0.030
(No.) /
(Cr) 5pm-7pm

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