1.2311, 1.2312, P20 / P20+S, UNS T51620 - tool steel, data according to DIN 17350

Standard Grade
Chemical composition %
C: Si: Mn: P: S: Cr: Mo:
EN 1.2311 - 40CrMnMo7
0.35 - 0.45 0.2 - 0.4 1.3- 1.6 <0.035 <0.035 1.8 - 2.1 0.15 - 0.25
DIN 1.2312 - 40CrMnMoS8-6
0.35 - 0.45 0.3 - 0.5 1.4- 1.6 <0.03 0.05 - 0.10 1.8 - 2.0 0.15 - 0.25
UNS UNS T51620 - P20
0.28 - 0.40 0.2 - 0.8 0.6- 1.0 <0.03 <0.03 1.4 - 2.0 0.30 - 0.55
UNS P20+S
0.4 0.35 1.5 - 0.05 1.9 0.2
AFNOR 40CMD8
0.35 - 0.45 0.15 - 0.40 1.35 - 1.65 - - 1.75 - 2.15 0.15 - 0.30
UNE F-5302
0.35 - 0.45 0.2 - 0.4 1.3- 1.6 <0.03 <0.02 1.8 - 2.1 0.15 - 0.25

1.2311, 1.2312, UNS T51620 – description

1.2311 and 1.2312 are plastic mould tool steels, suitable to operate in high temperature, used mainly for plastic moulds, hydroforming tools and frames for plastic pressure dies. They are highly hardenable, resistant to tempering and strong in high temperature.

1.2311 enables better texturing and polishability compared to 1.2312, making an A-2 surface finish easy to obtain. However, over-polishing may lead to pitting.

1.2312 is, on the other hand, better machinable compared to 1.2311.

Welding is possible but difficult. Pre-heating is necessary. After welding, the workpiece must be cooled down and the tempered.


Physical and mechanical properties

1.2311/1.2312 - general physical and mechanical properties in ambient temperature:

  • Density: 7.84 g/cm3
  • Linear expansion coefficient: 12.4 *10-6m/(m*K)
  • Thermal conductivity: 34 W/(m*K)
  • Hardness (in soft annealed condition): < 235 HB
  • Hardness (in hardened and tempered condition): < 51 HRC

The linear expansion coefficient of 1.2311 steel, in high temperature and in hardened and tempered condition:

  • Temperature range: 20-200 °C - 13 *10-6m/(m*K)
  • Temperature range: 20-300 °C - 13,4 *10-6m/(m*K)

Thermal conductivity of 1.2311 steel, in high temperature and in hardened and tempered condition:

  • Testing temperature: 150 °C - 34 W/(m*K)
  • Testing temperature: 200 °C - 33,6 W/(m*K)
  • Testing temperature: 250 °C - 32,9 W/(m*K)
  • Testing temperature: 300 °C - 31,9 W/(m*K)

The linear expansion coefficient of 1.2312 steel, in high temperature and in hardened and tempered condition:

  • Temperature range: 20-200 °C - 13 *10-6m/(m*K)
  • Temperature range: 20-300 °C - 13,7 *10-6m/(m*K)

Thermal conductivity of 1.2312 steel, in high temperature and in hardened and tempered condition:

  • Testing temperature: 150 °C - 40,4 W/(m*K)
  • Testing temperature: 200 °C - 40,4 W/(m*K)
  • Testing temperature: 250 °C - 39,9 W/(m*K)
  • Testing temperature: 300 °C - 39,0 W/(m*K)

Hardness of steel 1.2311 and 1.2312 in hardened and tempered condition, at various tempering temperatures:

  • Tempering temperature: 200 °C - 50 HRC
  • Tempering temperature: 300 °C - 48 HRC
  • Tempering temperature: 400 °C - 46 HRC
  • Tempering temperature: 500 °C - 42 HRC
  • Tempering temperature: 600 °C - 36 HRC
  • Tempering temperature: 700 °C - 28 HRC

Heat treatment and working

Recommended working and heat treatment parameters for the alloys:

  • Forging: 1100-850 °C
  • Rolling: 1100-850 °C
  • Quenching: 840-870 °C
  • Soft annealing: 710-740 °C

We deliver this steel alloy as:

  • Forgings
  • Round bars
  • Flat bars

Replacements, equivalents and other designations:

1.2311, 1.2312, 40CrMnMo7, 40CrMnMoS8-6, P20+S, UNS T51620, P20, 40Ch2GM, 35CrMo8, 40CMD8, F-5302, A681, 40Х2ГМ


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