Characteristics and Production Application of 304 Stainless Steel 3/4H Steel Sheet

1、 Definition and Classification

304 stainless steel 3/4H hard state is a medium to high hardness state achieved through cold rolling work hardening process, with a hardness level between 1/4H (soft state) and full hard state (FH), belonging to the semi hard state material. The cold rolling deformation is usually controlled at 25% -35% to achieve a stable balance between strength and ductility.

2、 Production process and workflow

Cold rolling processing

Using a 20 roll Sendzimir rolling mill for multi pass rolling, the thickness is rolled from the initial hot-rolled plate (such as 3mm) to the target specification (such as 2.23mm).

After rolling, the surface oxide layer and impurities are removed by degreasing and cleaning through a cold strip annealing and pickling unit.

Finally, the shape of the board was improved through the re rolling and straightening process, ensuring a flatness error of ≤ 3mm/m.

Work hardening control

By adjusting the rolling reduction rate and deformation speed, the tensile strength of the material can reach 800-900MPa, and the hardness (HV) can be increased to 250-350, meeting the 3/4H hard state standard.

3、 Key performance parameters

Source of hard state parameters for indicator 3/4H

Tensile strength (MPa) 800-900

Hardness (HV) 250-350

Elongation rate (%) 10-15

Surface roughness (Ra) ≤ 0.5 μ m (precision cold rolling)

4、 Core application areas

Precision stamping parts

Suitable for stamping hard sheet metal with a thickness of ≤ 0.8mm (such as electronic components, connectors), it needs to be matched with powder high-speed steel PM23 mold to resist cracking.

High strength structural components

Used for automotive fasteners, chemical pipeline supports, and other scenarios, replacing traditional carbon steel and improving corrosion resistance.

New energy equipment

As a bipolar plate substrate for hydrogen fuel cells, it is necessary to achieve lightweight through the synergy of ultra-thin (such as 0.2mm) and high hardness.

5、 Market supply and selection

Product specifications

Thickness range: Conventional 0.05-3.0mm (in stock), customizable ultra-thin (0.03mm) or ultra wide (1250mm) specifications.

Surface treatment: Provides options such as cold-rolled precision surface (2B) and brushed surface (HL).

6、 Precautions

Residual stress control: Hard plates should avoid direct welding and, if necessary, undergo stress relief annealing at 300-450 ℃.

Selection matching: When stamping high hardness materials, it is necessary to optimize the mold clearance (recommended to be 8% -12% plate thickness) to reduce burrs.