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Carbon Spring Steel
BRAND: PROMISTEEL
GRADES: 65Mn, 70#, 85#, AISI 1065, 1075, 1085
SHAPES: Round Bar, Flat Bar, Hot/Cold Rolled Strip, Wire Rod
DELIVERY CONDITION: Hot Rolled, Annealed, Cold Rolled, Quenched & Tempered
SURFACE: Black, Pickled, Oiled, Blue Finish (for strip)
HARDNESS: Annealed ≤220 HB; Quenched 42-50 HRC
APPLICATION: Harrow Discs, Plough Shares, Clips, Washers, Mattress Springs
MOQ: 25 Tons
High Quality Carbon Spring Steel is the most versatile and cost-effective material in the spring industry. Defined by a carbon content typically between 0.60% and 0.90%, these steels offer a reliable balance of elasticity, hardness, and wear resistance.
Our flagship grade, 65Mn (AISI 1566 equivalent), is the "Gold Standard" for manufacturing agricultural wear parts (like harrow discs and plough shares) and flat springs (clips and washers). Unlike alloy steels, carbon spring steel provides sufficient performance for general applications at a significantly lower cost, making it the preferred choice for high-volume manufacturing.
Product Specifications & Grade Equivalents
We supply high-carbon spring steels meeting GB, ASTM, and DIN standards, available in bars for forging and strips for stamping.
Table-1
Select the right grade for your specific application.
International Grade Comparison |
||||
| GB (China) | ASTM / AISI (USA) | DIN (Germany) | JIS (Japan) | Primary Use |
| 65Mn | 1566 | - | SWRH 67B |
Agri-blades, Round Springs |
| 70# | 1070 | 1.1231 (C70) | SWRH 72A |
Wire Springs, Mattress Wire |
| 85# | 1085 | 1.1269 (C85) | SWRH 82B |
High Strength Clips, Washers |
| T9A | W1-09 | 1.1625 | SK4 |
Cold-Rolled High-Carbon Strip |
Table-2
Strict control of Manganese (Mn) content ensures deep hardenability.
Chemical Composition (Mass Fraction %) |
|||||
| Grade | C | Si | Mn | P | S |
| 65Mn | 0.62~0.70 | 0.17~0.37 | 0.90~1.20 | ≤0.030 | ≤0.030 |
| 70# / 1070 | 0.67~0.75 | 0.17~0.37 | 0.50~0.80 | ≤0.030 | ≤0.030 |
| 85# / 1085 | 0.82~0.90 | 0.17~0.37 | 0.50~0.80 | ≤0.030 | ≤0.030 |
Table-3
Diverse forms for Stamping, Coiling, and Forging.
Supply Range & Formats |
|||
| Product Form | Dimensions (mm) | Delivery Condition |
Typical Application |
| Steel Strip | Thickness: 0.1-5.0 | Cold Rolled / Blue / Bright |
Clips, Washers, Saw Blades |
| Flat Bar | Thickness: 3-40 | Hot Rolled/Slit Edge |
Agricultural Discs, Knives |
| Round Bar | Dia: 5.5 - 100 | Hot Rolled / Annealed |
Coil Springs, Tools |
| Wire Rod | Dia: 5.5 - 20 | Sorbitized / Pickled |
Wire Drawing (Mattress Springs) |
Why Choose Our Carbon Spring Steel?
Optimized for Agriculture
Our 65Mn flat bars are specially rolled with consistent grain flow, making them ideal for heat-treating into durable, wear-resistant Rotary Tiller Blades and Harrow Discs that resist breaking in rocky soil.
Superior Surface Quality
For strip and wire applications, surface defects (like scratches or decarburization) can cause fatigue failure. We supply Pickled and Oiled or Cold Rolled surfaces that are defect-free.
Cost-Effective Performance
For non-critical springs (e.g., clips, lock washers, door springs), Carbon Spring Steel offers 90% of the performance of Alloy Steel at 70% of the cost.
Good Formability
In the annealed condition, our strips and wires can be easily stamped, bent, or coiled before the final quenching and tempering process.
Typical Applications
Agricultural Machinery
The largest market for 65Mn. Used for manufacturing plough shares, coulters, cultivator shovels, and mower blades.
Hardware & Fasteners
Circlips, spring washers, lock nuts, and hose clamps made from 1070/1085 strip.
Furniture & Bedding
High-carbon steel wire (70#/72A) is the standard material for mattress springs and sofa zigzag springs.
Cutting Tools
Bandsaw blades and simple hand tools.
FAQ
Q1: What is the US equivalent of 65Mn?
A1: The closest US equivalent is AISI 1566. Many people also compare it to AISI 1065, but 65Mn has higher Manganese (0.90-1.20%), which gives it better hardenability and wear resistance than standard 1065. This makes 65Mn superior for agricultural blades.
Q2: Can you supply heat-treated (blue) spring strip?
A2: Yes, we supply Quenched and Tempered (Hardened) spring steel strip with a Polished Blue or Yellow finish. This material is ready to use for making shutter springs or trowels without further heat treatment.
Q3: Is 65Mn suitable for heavy-duty truck springs?
A3: Generally, no. For heavy-duty suspension (trucks), we recommend Alloy Spring Steels like SUP9 (5155) or 5160. 65Mn is better suited for thinner agricultural blades or light-duty coil springs where heat build-up is not a major issue.
Q4: How do you package the steel strip?
A4: Our cold-rolled strips are oiled and wrapped in waterproof paper, then placed on wooden pallets to prevent rust during sea freight. Coil weights can be customized to your machine's requirements.
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