P20+S/40CrMnMoS 8 6/1.2311/618 Plastic Special Tool Steel, Tool
steel bar
Description:
P20 is a pre hardened high tensile tool steel which offers ready
machineability in the hardened and tempered condition, therefore
does not require further heat treatment . This eliminates the
risks, cost, and waiting time of heat treatment thus avoiding the
associated possibility of distortion or even cracking. Subsequent
component modifications can easily be carried out.
Applications: Typically used for relatively low temperature applications such as
die casting dies and injection molds.Suitable for a wide range of
injection moulds, blow moulds and extrusion dies for plastic.
Steel Grade:
GB 3Cr2Mo, %
| C | Si | Mn | P | S | Cr | Mo |
| 0,28 - 0,40 | 0,20 - 0,80 | 0.60 - 1,00 | <= 0,035 | <= 0,035 | 1,40 - 2,00 | 0,30 - 0,55 |
DIN- 1.2311 , %
| C | Si | Mn | P | S | Cr | Mo |
| 0,35 - 0,45 | 0,20 - 0,40 | 1,30 - 1,60 | <= 0,035 | <= 0,035 | 1,80 - 2,10 | 0,15 - 0,25 |
Similar grade: AISI-P20 ,618,M202,PBD25, SCM4
Hardening : 1050 - 850 °C (oil)
Delivery Condition:
| GB/T1299-2000 | DIN | AISI |
| Annealed (HB) | 330~280 | <=230 | 150~180 |
| Harden(HRC) | 30~34 | 46~51 | 64~58 |
Size available:
Square/Round Bar: 12~ 500mm
Flat: thickness,20~ 500mm , width, 500mm , 600mm , 700mm , 800mm ,
900mm , 1000mm , 1200mm , 1500mm , 1600mm , 1800mm , 2000mm .
Length: Contracted.
Forging:
Heat slowly and uniformly to 1050°C. Do not forge below 930°C.
After forging cool slowly.
Annealing:
P20 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 and thoroughly at the selected tempering
temperatures and hold at heat for one hour per 25 millimetre of
total thickness.
Nitriding:
Moulds machined from pre hardened P20 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.
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:
P20 can be flame or induction hardened to a hardenss of 50 to 55
HRc. Cooling in air is preferable. 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 P20 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 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.
