Alloy & tool steel
1.2312 plastic mould steel (40CrMnMoS8-6)
Pre-hardened plastic mould steel with sulphur for easy machining; forged flat and block, round.
1.2312, EN ISO 4957 name 40CrMnMoS8-6, is a plastic mould steel; its closest American equivalent is P20 with sulphur (P20+S). The Iranian market calls it 'plastic mould steel 2312'.
It is supplied pre-hardened, so the mould is machined without later heat treatment, and the added sulphur makes machining easier. The same sulphur makes it unsuitable for mirror polishing and photo-etching; for those, sulphur-free grades such as 1.2311 or 1.2738 are asked for.
Equivalents
- Material number (DIN)
- 1.2312
- EN name
- 40CrMnMoS8-6
- Standard
- EN ISO 4957
- AISI/SAE (approx.)
- P20+S
- Iranian market name
- plastic mould steel 2312
- Nominal density
- 7.85 kg/dm³
Chemical composition
| Element | Range (%) |
|---|---|
| C | 0.35–0.45 |
| Si | 0.30–0.50 |
| Mn | 1.40–1.60 |
| Cr | 1.80–2.00 |
| Mo | 0.15–0.25 |
| S | 0.05–0.10 |
Mass %, ranges of EN ISO 4957; the heat certificate of the delivered material is what the contract relies on.
Hardness and delivery state
Supplied pre-hardened (quenched and tempered) at about 280–325 HB. Blocks are usually saw-cut to the ordered size, and the cut piece is weighed.
Heat treatment
Supplied pre-hardened, it usually needs no heat treatment. Stress relieving after heavy machining is possible, and the surface can be nitrided for more wear resistance.
Typical uses
- Plastic injection mould plates and cavities
- Holder plates and mould bases
- Parts machined pre-hardened, without heat treatment
Delivery forms and size ranges
- Forged flat and block
- 260×310 … 620×620 mm
- Round bar
- Ø 200–350 mm
The ranges the market offers, not a stock list. Rounds above about 100 mm are usually forged and traded in diameter bands.
Sizes and weights
Nominal weights at a density of 7.85 kg/dm³ (1.2312). The actual weight is weighed, and tool steel is usually sold by the weight of the cut piece.
| Diameter (mm) | kg per metre |
|---|---|
| Ø 200 | 246.62 |
| Ø 250 | 385.34 |
| Ø 300 | 554.88 |
| Ø 350 | 755.26 |
| Width × thickness (mm) | kg per metre |
|---|---|
| 260 × 310 | 632.71 |
| 300 × 500 | 1,177.5 |
| 400 × 600 | 1,884 |
| 620 × 620 | 3,017.54 |
What to include in your request
- Grade and material number, and the standard if your drawing requires one
- Form: round, flat or block, square or plate
- Exact size: diameter, width × thickness, or plate thickness
- Cut length, or the number and size of pieces, or full bars
- Delivery state: normalised, annealed, pre-hardened or quenched and tempered, turned
- Quantity in kg or tonnes, place and date of delivery
- Preferred origin (made in Iran or imported), if it matters to you
Documents you can ask for
- EN 10204 type 3.1 inspection certificate (heat analysis and hardness)
- Ultrasonic test (UT) report for forged sizes
- Hardness report for pre-hardened or quenched and tempered material
Frequently asked questions
What is 1.2312 steel?
1.2312, EN ISO 4957 name 40CrMnMoS8-6, is a plastic mould steel; its closest American equivalent is P20 with sulphur (P20+S). The Iranian market calls it 'plastic mould steel 2312'.
What is the density of 1.2312?
The nominal density of 1.2312 is about 7.85 kg/dm³ (g/cm³); the weight table on this page and the weight calculator use this value. The actual weight is weighed.
What is the equivalent of 1.2312?
1.2312 is listed in EN ISO 4957 as 40CrMnMoS8-6; its closest American equivalent is AISI P20+S. Equivalents are approximate: if your drawing requires a specific standard, name it in the request.
What is the hardness of 1.2312?
1.2312 is supplied pre-hardened at about 280–325 HB and is machined into moulds without later heat treatment.
How do I get a quote for 1.2312?
Send the grade, form and size, the cut length or number of pieces, the delivery state and the documents you need. We review the request and send you an offer.