65Mn Carbon Steel Strip — Factory Direct Supplier | Huaxia-Steel
Huaxia-Steel is a dedicated carbon steel manufacturer and supplier producing high-quality 65Mn carbon steel strip in continuous cold-rolled and annealed coil form. The 65Mn carbon steel strip we supply is engineered for spring applications, cutting tools, and high-fatigue components where consistent elasticity, flatness, and surface cleanliness are mandatory. As a factory-direct source we control the full production chain from hot-rolled substrate through cold rolling, heat treatment, and edge conditioning, allowing us to hold tight dimensional tolerances and deliver material with a full Mill Test Certificate on every shipment.
This product page documents the grade definition, available specifications, chemical composition, mechanical properties, international equivalents, applicable standards, typical applications, quality assurance, and packaging of our 65Mn strip. All values stated reflect standard commercial production and can be tightened or widened to meet customer drawings.
1. Product Overview
65Mn is a Chinese spring-steel grade defined under GB/T 1222 (Spring steels). The designation breaks down as follows: “65” indicates a nominal carbon content of approximately 0.65%, and “Mn” denotes that manganese is the primary alloying element added to improve hardenability and strength. The 65Mn carbon steel strip is a high-carbon, medium-manganese steel valued for its high elasticity, good hardenability, and excellent response to heat treatment. After suitable hardening and tempering it develops a fine martensitic or tempered martensitic structure that combines high strength with useful resilience.
1.1 Grade Definition and Characteristics
The nominal composition of 65Mn is about 0.65% carbon plus manganese, which positions the grade between plain carbon spring steels and the more highly alloyed silicon-manganese spring steels. Key characteristics of the 65Mn carbon steel strip supplied by Huaxia-Steel include:
- High elastic limit and yield ratio, enabling thin sections to store substantial spring energy.
- Good hardenability from the manganese addition, reducing the risk of soft spots through the strip thickness.
- Excellent fatigue resistance under cyclic bending loads when surface decarburization is controlled.
- Superior wear resistance relative to low-carbon strip, suitable for blade and edge applications.
- Readily cold-formable in the annealed or quarter-hard condition before final hardening.
1.2 Why Choose 65Mn Carbon Steel Strip
Compared with 60Si2Mn or 55Cr3, 65Mn offers a lower alloy cost while still meeting the demands of many flat spring and blade products. It is the preferred choice when a balance of cost, strength, and formability is required rather than the maximum stress capacity of silicon-manganese grades. Huaxia-Steel supplies this strip with controlled decarburization depth, typically limited to a maximum of 0.02 mm per surface side for spring-critical orders.
2. Specification Table
The following table lists the standard production envelope for 65Mn carbon steel strip at Huaxia-Steel. Non-standard dimensions and tempers can be quoted on request.
| Parameter | Available Range | Standard Tolerance |
|---|---|---|
| Thickness | 0.10 – 3.00 mm | ±0.01 mm (≤0.50 mm), ±0.02 mm (>0.50 mm) |
| Width | 5 – 300 mm | ±0.10 mm (slit edge), ±0.15 mm (square edge) |
| Temper / Hardness Condition | Annealed, Quarter-hard, Half-hard, Full-hard | Per customer hardness band |
| Coil Inner Diameter (ID) | 200, 300, 400, 508 mm | ±5 mm |
| Coil Outer Diameter (OD) | Max 1200 mm | Weight up to 1000 kg per coil |
| Edge Type | Round edge, Square edge, Deburred slit edge | Edge radius per EN 10140 option |
| Surface Finish | Bright annealed, Polished, Blued, Phosphate | Free of scratches >0.05 mm |
| Decarburization Depth | Max 0.02 mm per side (spring grade) | Microsection verified |
2.1 Temper Conditions Explained
- Annealed (soft): Fully recrystallized structure for maximum formability; hardness around 150–190 HV.
- Quarter-hard: Light cold reduction; suitable for moderate forming with spring-back allowance.
- Half-hard: Higher yield for lightly formed parts; reduced spring-back.
- Full-hard: As-rolled high strength for flat springs that are not further heat treated.
3. Chemical Composition
The chemical composition of 65Mn carbon steel strip conforms to GB/T 1222 and is verified by spectrographic analysis on every heat. Typical ladle analysis is shown below.
| Element | Symbol | Content (wt%) |
|---|---|---|
| Carbon | C | 0.62 – 0.70 |
| Manganese | Mn | 0.90 – 1.20 |
| Silicon | Si | 0.17 – 0.37 |
| Phosphorus (max) | P | ≤ 0.035 |
| Sulfur (max) | S | ≤ 0.035 |
| Chromium (max) | Cr | ≤ 0.25 |
| Nickel (max) | Ni | ≤ 0.30 |
| Copper (max) | Cu | ≤ 0.25 |
3.1 Composition Effects
The carbon content of roughly 0.65% is the primary contributor to hardenability and peak strength. Manganese at 0.90–1.20% refines the pearlite, raises the hardenability, and offsets the tendency of sulfur to form low-ductility inclusions. Silicon, held at 0.17–0.37%, acts as a deoxidizer and provides modest solid-solution strengthening. Phosphorus and sulfur are kept low to protect surface quality and fatigue life. Tight control of these elements is what gives our 65Mn carbon steel strip its repeatable performance.
4. Mechanical Properties
Mechanical properties depend heavily on the temper and any post-supply heat treatment. The table below summarizes typical values for material shipped in common conditions. Values are indicative; final properties are confirmed by the Mill Test Certificate.
| Condition | Tensile Strength (MPa) | Yield Strength (MPa) | Hardness (HV) | Bend Test (180°) |
|---|---|---|---|---|
| Annealed | 600 – 750 | 350 – 450 | 150 – 190 | Good, no cracking at 1.5×t |
| Quarter-hard | 750 – 900 | 550 – 700 | 200 – 250 | Bend at 2×t |
| Half-hard | 900 – 1050 | 750 – 900 | 250 – 310 | Bend at 3×t |
| Full-hard | > 1000 | > 900 | 320 – 400 | Limited, formed before hardening |
4.1 Elastic Limit and Spring Performance
The elastic limit of 65Mn is a critical parameter for spring design. In the hardened and tempered condition the material can reach an elastic limit of 800–1100 MPa depending on tempering temperature. Lower tempering temperatures favor higher strength but reduced toughness, while higher tempering temperatures around 400–500 °C improve ductility for dynamic-load springs. For static flat springs, the 65Mn carbon steel strip is often used in the full-hard or lightly tempered condition to maximize load capacity in thin cross-sections.
4.2 Hardness and Bend Test Notes
Bend testing is performed across and along the rolling direction. Because cold-rolled strip work-hardens anisotropically, transverse bend values are more conservative and govern spring forming limits. Huaxia-Steel reports both directions on request. Surface decarburization, if excessive, sharply reduces fatigue bending life, which is why our spring-grade strip is processed to limit decarburization depth.
5. Equivalent Grades
65Mn is broadly comparable to several international spring-steel designations. The table maps the closest equivalents so designers can substitute with confidence.
| China (GB) | USA (AISI / ASTM) | Germany (DIN) | Japan (JIS) | Notes |
|---|---|---|---|---|
| 65Mn | 1065 | 65Si7 | SUP9 / 65C | Closest general spring-steel match |
| 65Mn | 1566 | 1.0904 | SUP9A | Higher Mn variant |
| 65Mn | 1065 modified | Ck67 | SWRH67B | Wire-rod equivalent |
5.1 Substitution Guidance
When replacing AISI 1065 or DIN 65Si7 with our 65Mn carbon steel strip, note that 65Si7 contains elevated silicon which raises elastic limit but reduces weldability. For most flat-spring and blade uses the substitution is straightforward, provided heat-treatment temperatures are adjusted. JIS SUP9 and 65C are frequently used for leaf springs and similar laminated applications and correspond well to 65Mn in the spring-tempered condition.
6. Manufacturing Standards
Huaxia-Steel produces and inspects 65Mn carbon steel strip against the following principal standards:
- GB/T 1222 — Spring steels; the defining Chinese standard for 65Mn composition and delivery condition.
- ASTM A29 / A29M — Standard specification for general requirements for steel bars, carbon and alloy, covering comparable carbon grades.
- JIS G4801 — Japanese standard for spring steels, relevant for SUP9 / 65C equivalence.
- EN 10132 — Cold-rolled narrow steel strip for heat-treatment; defines dimensional and surface tolerances for strip supply.
6.1 Production Route
Production begins with electric-furnace or converter steelmaking followed by continuous casting and hot rolling into strip substrate. The substrate is pickled, cold-rolled in multiple passes with inter-annealing, and finished by bright annealing under protective atmosphere to avoid oxidation. Final slitting sets the width and edge profile. For hardened and tempered deliveries, the strip passes through a controlled furnace and quench followed by tempering. Each stage is logged for traceability.
7. Applications
The combination of elasticity, strength, and economy makes 65Mn carbon steel strip suitable for a wide range of formed and spring components:
- Flat springs and scroll springs in automotive, appliance, and electrical devices.
- Saw blades and band-saw backings where wear resistance and edge retention matter.
- Clips, fasteners, and retaining rings formed from thin strip.
- Washers and spring washers requiring consistent load-deflection behavior.
- Measuring tapes and rules needing dimensional stability and flex life.
- Agriculture blades such as sickle sections and mower knives.
- Shims, feeler gauges, and precision spacers where flatness is critical.
7.1 Forming and Heat-Treatment Tips
For springs made from annealed strip, form the part first, then harden by austenitizing around 780–830 °C followed by oil or water quenching, and temper at 350–500 °C to the target hardness. Avoid excessive heating time to limit decarburization. When using full-hard strip, design parts to be formed cold with generous bend radii and minimal spring-back correction. Huaxia-Steel can supply pre-hardened and tempered 65Mn carbon steel strip to save downstream processing.
8. Quality Assurance
Every coil of 65Mn carbon steel strip shipped by Huaxia-Steel is accompanied by a Mill Test Certificate (MTC) to EN 10204 3.1. Our quality system covers incoming chemistry, in-process dimensional checks, and final inspection.
8.1 Inspection Items
- Chemical verification: Spectrographic analysis of each heat against the composition table above.
- Hardness testing: HV or HRC measured across the width and along the coil length at defined intervals.
- Surface inspection: Visual and microscope check for scratches, pits, rust, and oxide; bright surface free of edge cracks.
- Edge inspection: Verification of edge profile, burr height below 0.02 mm, and freedom from edge waves.
- Decarburization check: Microsection measurement to confirm depth limits for spring grades.
- Flatness and camber: Controlled to customer specification for automated stamping lines.
8.2 Documentation
The MTC records heat number, dimensions, temper, mechanical results, and compliance statements. Additional third-party inspection (SGS, BV, TUV) can be arranged before shipment on request.
9. Packaging & Shipping
Proper protection is essential to preserve the bright surface of 65Mn carbon steel strip during transit and storage. Our standard packaging procedure is as follows:
- Each coil is wrapped with VCI (volatile corrosion inhibitor) anti-rust paper to block moisture and salt-air corrosion.
- An inner and outer layer of polyethylene film seals the coil against humidity.
- Coils are radially strapped with steel or PET bands and fitted with edge protectors.
- For export, coils are palletized on wooden or steel skids and corner-guarded.
- Container loading is photo-documented, with dunnage used to prevent coil-to-coil contact.
9.1 Storage Recommendations
Store coils in a dry, covered warehouse below 60% relative humidity. Avoid outdoor exposure. If surface passivation or oiling is required for long sea transit, specify at order time so we apply a temporary rust-preventive film that is easily cleaned before forming.
10. Request a Quote for 65Mn Carbon Steel Strip
Huaxia-Steel supplies 65Mn carbon steel strip in thicknesses from 0.10 mm to 3.00 mm and widths from 5 mm to 300 mm, in annealed, quarter-hard, half-hard, and full-hard tempers, with round or square edges and bright, polished, blued, or phosphate surfaces. We deliver with full MTC documentation and can match GB/T 1222, ASTM A29, JIS G4801, and EN 10132 requirements.
To receive a competitive factory-direct quotation and a sample Mill Test Certificate for 65Mn carbon steel strip, please contact the Huaxia-Steel sales team with your required thickness, width, temper, coil weight, and destination. Our engineers will confirm availability, lead time, and packaging options, and can advise on equivalent grades such as AISI 1065, DIN 65Si7, or JIS SUP9 / 65C for your design. Reach out to Huaxia-Steel today for 65Mn strip quotes and MTC, and let our technical staff help you specify the right spring-steel strip for your application.
