304 Stainless Steel Elastic Steel Strip

 Alternative Name 

304 stainless steel spring steel strip

Cold-rolled hard strip steel of 304 stainless steel

304 stainless steel hard strip

304 stainless steel high-strength elastic tape

304 stainless steel quenched and tempered steel strip (emphasizing the acquisition of specific hardness and elasticity through cold rolling

304 1/4H, 1/2H, 3/4H, H, EH, SH hard state steel strips (different cold-rolled hardening degree grades)

 Product Introduction 

304 stainless steel elastic steel strip is a special state of stainless steel strip made from 304 austenitic stainless steel as raw material. Through precise cold rolling process, it is rolled to a specific thickness at room temperature, and in this process, its strength, hardness and elastic limit are significantly improved. It does not gain elasticity through heat treatment quenching, but takes advantage of the work hardening characteristics of austenitic stainless steel.

Core features: Excellent elastic properties (good resilience and fatigue resistance) + inherent corrosion resistance of 304 stainless steel, non-magnetic (may have weak magnetism after cold working) and good formability (within the elastic range).

Key process: Precise control of the degree of cold rolling hardening (reduction) to achieve the required mechanical properties (such as hardness, tensile strength, yield strength, and elongation).

Common specifications

• Thickness: 0.03mm - 3.0mm (commonly seen in 0.05mm - 1.5mm)

• Width: 3mm - 1000mm (customizable slitting available)

• Hardness state 1/4H (approximately HV 250-310), 1/2H (approximately HV 310-370), 3/4H (approximately HV 370-430), H (fully hard, approximately HV 430-480), EH (Extra hard, >480HV), SH (Spring hard, the highest hardness grade). The higher the hardness, the better the elasticity, but the lower the plasticity and formability.

• Surface conditions: 2B (bright annealing after cold rolling, pickling and passivation), BA (bright annealing), No.3 (frosted), No.4 (brushed), etc.

 Product Features 

• High strength and high elasticity: Through cold rolling work hardening, the yield strength and tensile strength are significantly enhanced, endowing it with excellent elastic recovery ability and resistance to permanent deformation.

• Excellent corrosion resistance: Inheriting the good corrosion resistance of 304 stainless steel (18% chromium, 8% nickel), it can resist the corrosion of the atmosphere, water vapor, and various chemical media (such as weak acids and weak alkalis), and is suitable for environments that require rust prevention.

• Non-magnetic/weakly magnetic: The austenitic structure is basically non-magnetic in the solution state. After cold rolling processing, a small amount of martensitic transformation may occur, resulting in weak magnetism (magnetic permeability is usually less than 1.02), but it is much lower than that of ferritic or martensitic stainless steel. It is very important for applications that require low magnetism.

• Good fatigue life: It has excellent fatigue resistance under repeated bending or compression deformation, making it suitable for manufacturing elastic components that need to withstand alternating loads for a long time.

• Certain formability: Within the elastic deformation range, it can undergo forming processes such as bending, stamping, and winding (it is more difficult to form compared to the annealed state). Choosing the appropriate hard state grade (such as 1/2H, 3/4H) can strike a balance between elasticity and formability.

• Smooth and beautiful surface: Different surface treatments (such as 2B, BA, frosted, brushed) can be provided according to requirements to meet the appearance and functional requirements (such as reducing friction and improving contact).

• Broad performance adjustability: By controlling the degree of cold rolling (hardness grade), its mechanical properties (strength, elasticity, toughness) can be precisely adjusted to meet different application requirements.

• Environmental protection and hygiene: Meets the requirements for food contact materials (specific certification is required), is easy to clean, and is commonly used in medical and food equipment.

 Application scenarios (based on its elasticity and corrosion resistance) 

Electronic appliances

Katto spring plates, shielding cover spring plates, battery contacts, connector terminals, micro switch spring plates, and heat sink clamps in mobile phones/computers.

Elastic elements of relays and contactors.

Automotive industry

Sensor spring plates, fuel injection system parts, seat belt retractor spring plates, various wire harness fixing clamps, sealing gaskets (elastic ones are required).

Medical devices

Spring components of surgical instruments, forceps, fixtures, endoscope parts, auxiliary elastic parts of implantable instruments, and probes of detection equipment.

Precision Machinery and Instrumentation

Precision springs (such as torsion springs, compression springs, and leaf springs), diaphragms, bellows, Pointers, hairsprings, precision fixtures, and elastic elements in measuring instruments.

Household appliances

Washing machine and dishwasher door lock spring plates, coffee machine and kettle temperature controller spring plates, reset springs for various buttons, and connection spring plates inside electrical appliances.

Industrial equipment

Valve seals (requiring elastic compensation), pump springs, filter elements, safety valve disc springs, mechanical seals, conveyor belt guide clamps.

Building Hardware

Springs for high-quality door and window hardware, internal springs for locks, and torsion springs for invisible hinges.

Daily hardware and stationery

Folding knife back spring, binder spring, automatic pen internal spring, high-quality hairpin, clip.

 Product Advantages 

• Excellent performance combination: It simultaneously meets the requirements of elasticity and corrosion resistance, which is irreplaceable by ordinary carbon steel spring steel strips.

• Long service life: Corrosion resistance prevents performance degradation or fracture caused by rust, and good fatigue resistance extends the service life in dynamic applications.

• High reliability: Stable performance, weakly magnetic or non-magnetic, meeting specific requirements (such as precision instruments, electronic equipment).

• Good appearance and hygiene: The surface is smooth and clean, meeting both hygiene and aesthetic requirements.

• Strong customizability: Dimensions (thickness, width), hardness grades, surface conditions, and performance ranges can all be customized according to customer requirements.

• No heat treatment required: Its elasticity is directly obtained through cold rolling, eliminating the need for heat treatment processes such as quenching and simplifying the manufacturing process of some parts (though stress relief annealing may be necessary after complex forming).

 Customized Process 

Demand communication

Clarify the application scenarios and functional requirements (such as the required elastic force, deformation amount, and working environment).

Determine the key parameters: material (confirm 304), thickness, width, length/roll weight.

Determine the hardness grade (1/4H, 1/2H, 3/4H, H, EH, SH) or the target mechanical properties (such as the yield strength Rp0.2 range).

Select the surface condition (2B, BA, No.3, No.4, etc.) and surface quality requirements.

Discuss the packaging methods and transportation requirements.

Technical Assessment and Quotation

The supplier assesses the feasibility of the requirements (such as whether the thickness/width/hardness combination can be produced).

Provide detailed quotations and estimated delivery dates based on specifications, quantities and special requirements.

Sample confirmation (optional but recommended)

If necessary, the supplier shall provide small samples for the customer to test (dimensions, hardness, elasticity, corrosion resistance, etc.).

The customer confirmed that the sample met the requirements.

Formal order signing

Both parties confirm the technical specifications (usually in writing, by drawing or technical agreement).

Sign a purchase contract.

Production Scheduling and Raw material Preparation

The supplier arranges the production plan and prepares 304 stainless steel coil materials that meet the requirements.

Precision cold rolling processing

Multi-pass rolling is carried out on the precision cold rolling mill, and the reduction amount is strictly controlled to achieve the target thickness and hardness grade.

Process control: Monitor thickness, plate shape and surface quality.

Surface treatment

Carry out cleaning, pickling and passivation (2B), bright annealing (BA) or grinding (No.3, No.4) as required.

Refinement and slicing

Slitting to the precise width required by the customer.

Check the width and burr condition, and deburr if necessary.

Inspection and Testing

Inspection shall be conducted in accordance with the agreed standards (such as national standards, ASTM, JIS, and enterprise standards) and quality inspection procedures by both parties (for details, see below).

Packaging and Shipment

Package as required (such as anti-rust paper + stretch film + wooden box/iron box/pallet), and affix labels.

Arrange logistics transportation.

 Quality inspection process (Key control points) 

Raw material inspection

Check the material certificate (MTC/CofC) to verify whether the grade (304) and chemical composition (especially the contents ofC, Cr, and Ni) comply with the standards (such as ASTM A240).

Check the surface quality of the incoming material rolls (no serious defects).

Dimensional accuracy inspection

Thickness: Use a high-precision micrometer or an online thickness gauge for multi-point measurement to ensure that the thickness tolerance meets the requirements (such as ±0.005mm).

Width: Use a vernier caliper or projector to check the slitting width and tolerance (such as ±0.05mm).

Length/Roll weight: Check the actual length or weight.

Mechanical property testing

Hardness: Multi-point testing with a Vickers hardness tester (HV) or a Rockwell hardness tester (HRB/HRC - please pay attention to conversion and applicability) to confirm that it meets the specified hardness grade range.

Tensile test: Samples are taken to make tensile specimens, and tensile strength (Rm), yield strength (Rp0.2/Rp1.0), and elongation (A) are tested. This is the most crucial verification of elastic performance.

Bending/repeated bending test (as required) : Test its bending forming ability and fatigue resistance.

Surface quality inspection

Visual inspection: Inspect the surface of the strip under good lighting to ensure there are no scratches, indentations, roller marks, rust spots, oxidation colors, pockmarks, creases, peeling, cracks or other defects. The surface finish meets the requirements (such as 2B, BA).

Surface roughness test (as required) : Measure the Ra value using a roughness meter.

Plate shape (flatness) inspection

Lay the steel belt freely on the platform and check for warping, wavy edges, sickle bends, etc. Measure the unevenness (such as I-unit values).

Corrosion resistance spot check (as needed or regularly)

Salt spray test: Conduct a neutral salt spray test in accordance with standards (such as ASTM B117) (commonly 48 hours or 72 hours) to check for the appearance of red rust and evaluate corrosion resistance.

Copper-accelerated acetic Acid salt spray test (CASS) : A more rigorous test (on demand).

Inspection of other special requirements

Magnetic test (as required) : Use a permeability meter to measure the permeability to ensure it meets the low magnetic requirements.

Metallographic structure (as required) : Observe the microstructure to confirm the degree of cold rolling and whether there are any abnormal structures.

Packaging and Labeling Inspection

Check whether the packaging method complies with the contract requirements (moisture-proof and shock-proof).

Check whether the label information (grade, specification, hardness, batch number, quantity, standard, etc.) is clear and accurate.

Document Records

Issue a detailed factory inspection report (COA), including all key test results.

Retain inspection records and traceability information (batch number, furnace number).

 Summary 

304 stainless steel elastic steel strip, with its unique "cold rolling hardening" process, successfully combines the excellent corrosion resistance and non-magnetic/weakly magnetic properties of 304 stainless steel with high strength and high elasticity. This material is an ideal choice for manufacturing elastic components that operate in corrosive environments, precision electronics, medical fields, or those requiring non-magnetic or weakly magnetic conditions. The customizability of its performance and state, as well as its advantage of relatively no heat treatment, make it widely and indispensable in modern manufacturing. A strict quality inspection process is the key to ensuring its performance and reliability.

It is hoped that the above detailed introduction can help you have a comprehensive understanding of 304 stainless steel elastic steel strips. If there are more specific application or performance requirements, further discussions can be held.