Quenched and tempered steel
30CrNiMo8 / 1.6580 quenched and tempered steel
30CrNiMo8 is an alloy chromium-nickel-molybdenum quenched and tempered steel with Werkstoffnummer 1.6580 to EN 10083-3. Nickel and chromium are higher than in 34CrNiMo6, which gives higher through-hardening in heavy cross-sections. It is chosen when diameter and core requirements demand it – not as a replacement for 42CrMo4 at Ø80. Typical delivery is +QT (quenched and tempered), as round bar or forging. INDUSTRISTÅL cuts to size – even one piece without minimum charge – and ships with EN 10204 3.1.
Designations
- W.Nr.
- 1.6580
- EN standard
- 30CrNiMo8
- DIN
- 30CrNiMo8
- AISI/SAE
- 4340
- UNS
- G43400
- Group
- Alloy engineering steel
Mechanical properties
Typical +QT values according to EN 10083-3
+QT, round bar. The table shows the standardised ruling sections up to 250 mm.
| Ruling section | Re min. | Rm | A min. |
|---|---|---|---|
| d ≤ 16 mm | 1050 MPa | 1250–1450 MPa | 9 % |
| 16–40 mm | 1050 MPa | 1250–1450 MPa | 9 % |
| 40–100 mm | 900 MPa | 1100–1300 MPa | 10 % |
| 100–160 mm | 800 MPa | 1000–1200 MPa | 11 % |
| 160–250 mm | 700 MPa | 900–1100 MPa | 12 % |
Impact toughness (KV) is specified at min. 30–35 J depending on ruling section. Larger diameters and forgings are agreed according to the specific specification and certificate.
Chemical composition
Typical range according to EN 10083-3 (ladle analysis)
| Element | Range |
|---|---|
| C | 0.26–0.34 % |
| Si | max. 0.40 % |
| Mn | 0.30–0.60 % |
| P | max. 0.025 % |
| S | max. 0.035 % |
| Cr | 1.80–2.20 % |
| Mo | 0.30–0.50 % |
| Ni | 1.80–2.20 % |
Applications
- Very large and heavily loaded shafts
- Forgings and heavy rotor parts in +QT
- Heavy transmission parts and gear blanks
- Machine components with high requirements for core strength and toughness
Delivery conditions
- +QT (hardened and tempered)
- Round bar cut to size
- Often forged in large Ø
Heat treatment
30CrNiMo8 is hardened and tempered (+QT). Hardening and the higher content of nickel (~2 %), chromium (~2 %) and molybdenum ensure through-hardening in large cross-sections; tempering gives toughness. The condition is locked to the strength or hardness requirement on the drawing.
Machinability
Machining in +QT is demanding because of high strength and toughness. Rough machining and boring are best done before final hardening, or supplied pre-machined from the mill.
Weldability
Not intended for structural welding. Requires a separate procedure if welding is unavoidable.
Sawing and documentation
Sawing to fixed length and boring of the core as required – from a single piece to series without minimum charge. Forged piece when rolled round bar does not cover diameter or length. EN 10204 3.1 is included as standard at no charge. 3.2 and classification society are ordered when the PO requires it.
Frequently asked questions
- What is 30CrNiMo8 / 1.6580?
- 30CrNiMo8 (W.Nr. 1.6580) is a high-alloy Cr-Ni-Mo quenched and tempered steel to EN 10083-3, placed one step above 34CrNiMo6 in hardenability and strength at large cross-sections.
- When do you choose 30CrNiMo8 instead of 34CrNiMo6?
- When diameter and core requirements mean that 34CrNiMo6 (1.6582) no longer achieves the required through-hardening. Not “to be on the safe side” in moderate diameters.
- Can INDUSTRISTÅL supply 30CrNiMo8 round bar cut to size?
- Yes. We supply 30CrNiMo8 / 1.6580 as round bar and forgings in +QT, cut to your size – even a single piece without minimum charge – with EN 10204 3.1.
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