Spring steel
51Si7 / 1.5025 alloy engineering steel
51Si7 (1.5025) is silicon spring steel one carbon class below 56Si7. The grade is a DIN 17221 designation — it was not carried over to EN 10089, so there is no EN name to write on the certificate alongside it.
- Delivery conditions
- untreated, soft annealed or +QT
- Also known as
- 1.5025
Designations
- W.Nr.
- 1.5025
- DIN
- 51Si7
- Group
- Alloy engineering steel
What it is used for
Flat springs and hot-formed spring parts where the drawing says 51Si7.
Limits
Confirm that it is the DIN name the drawing means. If the purchase is to be made to EN 10089, 56Si7 (1.5026) is the closest standardised grade.
Delivery
We source 51Si7 from European mill partners as round bar, flat bar, square bar, cut to your dimensions and ship the certificate with the material. Typical condition: untreated, soft annealed or +QT. From a single cut piece to larger lots — with no minimum charge, so you do not have to buy a full commercial length to get what you need.
Certificates and documentation
51Si7 can be supplied with a material certificate to EN 10204, depending on producer, dimension and the requirements specified for the delivery. The heat and the delivery condition are what carry the certificate — a spring or bearing grade only gets its service properties after treatment, and that part is documented by whoever performs it. EN 10204 3.1 can be supplied on a wide range of our materials.
Dimension programme
| Form | Range | Note |
|---|---|---|
| Round bar | Ø2–35 mm drawn, Ø15–220 mm hot rolled, Ø230–710 mm forged | Drawn to DIN 671, hot rolled to DIN 1013, forged to DIN 7527. Bars in 3 or 6 m. State Ø and condition. |
| Flat bar | 20 × 3 mm to 200 × 20 mm | Flat spring steel in 5 or 6 m bars, cut to fixed length on request. Rounded edges or mill edge — state which. |
| Square bar | Same drawn and hot-rolled range as round | State side length and condition. Not every grade is run in square. |
The range is a delivery programme, not a stock statement. Length is cut to your drawing.
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Send your enquiry
State grade, dimensions and quantity — or attach a drawing. We reply with a quote.