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1.2311 40CrMnMo7
Technical Data
1.2311 is a pre hardened high tensile tool steel which offers ready machineability in the hardened and tempered condition, therefore does not always require further heat treatment . This eliminates the risks, cost, and waiting time of heat treatment and avoids the associated possibility of distortion or even cracking. Subsequent 1.2311 component modifications can easily be carried out.
Typical Analysis - 1.2311 Tool Steel
C.
Si.
Mn.
Cr.
Mo.
0.40%
0.40%
1.00%
1.20%
0.35%
Forging:Heat slowly and uniformly to 1050°C. Do not forge below 930°C. After forging cool slowly.
Annealing:1.2311 should always be annealed after forging and before rehardening. Heat uniformly to 770/790°C. Soak well and cool slowly in the furnace.
Hardening:Heat uniformly to 840/870°C until heated through. Quench in oil.
Tempering:Heat uniformly the 1.2311 tool thoroughly at the selected tempering temperatures and hold at heat for one hour per 25 millimetre of total thickness.
Tempering °C
100
200
300
400
500
600
700
HRc
51
50
48
46
42
36
28
N/mm²
1730
1670
1570
1480
1330
1140
920
Nitriding:Moulds machined from pre hardened 1.2311 may be nitrided to give a hard surface which is very resistant to wear and erosion. A nitrided surface also increases the corrosion resistance. The surface hardness after nitriding at a temperature of 525°C in ammonia gas will be approximately 650HV.
Temperature
Time
Approximate Depth of Case
525°C
20 hours
0.30mm
525°C
30 hours
0.35mm
525°C
60 hours
0.50mm
Tufftriding:Tufftriding at 570°C will give a surface hardness of approximately 700HV. After 2 hours treatment the hard layer will be approximately 0.01mm
Flame & Induction Hardening:1.2311 may be flame or induction hardened to a hardenss of 50 to 55 HRc. Cooling in air is a preferable option. Smaller pieces may however require forced cooling. Hardening should be immediately followed by tempering.
Hard Chromium Plating:After hard chromium plating the steel should be tempered for approximately 4 hours at 180°C, in order to avoid hydrogen embrittlement.
Case Hardening:In order to maintain maximum surface hardness 1.2311 may be case hardened. Before case hardening is carried out the steel should be annealed. To carburise, pack with carburising powder into a cast iron or heat resisting steel box and see that the articles are separated from the sides by at least two inches of carburising powder. Lute the lid with fireclay. Heat to the carburising temperature of 880°C and soak for sufficient time to give the required depth of case. Cool to 800/820°C and quench in oil. Tempering will then be necessary. Reheat to 200/300°C and allow to cool in the air to give a final surface hardness of Rockwell C55/59
Welding:Firstly heat to approximately 400 to 500°C. Weld .12311 at approximately 400 to 500°C and stress relieve. Use Chromium-Nickel-Molybdenum alloyed basic electrodes for welding of structural steels. Welding may also be carried out using an austenitic stainless steel electrode. In this case the stipulated increased working temperature may be modified, but the weld metal has a lower strength than the parent material.
Physical Properties: 1.2311
Temperature:
20°C
200°C
400°C
Density (Kg/m³)
7800
7750
7700
Coefficient of thermal expansion (per °C from 0°C)
-
12.7 x 10-6
13.6 x 10-6
Thermal conductivity (J/m.s °C)
29.0
29.5
31.0
Specific heat (J/kg °C)
460
-
-
Modulus of elasticity:
Kp/mm²
20 900
20 400
18 900
N/mm²
205 000
200 000
185 000
Machining:
Turning
Rough
Medium
Finish
Carbide Tools
Turning
Turning
Turning
Depth of cut (t) mm
min. 10
2-10
max. 2
Feed (s) mm
mm 1.0
0.3-1.0
max. 0.3
ISO Machining Group
P30-P40
P20-P30
P10
Cutting Speed
40-60
60-100
90-160
Milling:
Carbide Tools &
Rough
Finish
High Speed Steel Tools
Milling
Milling
Depth of cut (t)
min. 2
max.2
Feed (s) mm/tooth
min. 0.2
max. 0.2
ISO Machining Group
P30-P40
P10-P20
Carbide Tools:
Cutting Speed (v) m/min.
55-85
75-95
High Speed Steel Tools:
Cutting Speed (v) m/min.
10-20
15-30
Mechanical Properties (at room temperature) 1.2311
Tensile Strength
1000-1068 N/mm²
Yield Stress
861-930 N/mm²
Reduction of Area
45-50%
Elongation
14-17%