718 P20+Ni 1.2738 3Cr2NiMo plastic mould steel

3Cr2NiMo die steel is an improved version of 3Cr2Mo die steel, which is made by adding a mass fraction of 0.8%-1.2% nickel to 3Cr2Mo steel. The actual composition of P4410 steel produced in China is consistent with that of P20 improved 718 steel produced in Sweden.

The steel has high hardenability, as well as good polishing properties, EDM and skin processing properties. The pre-hardened product does not need to be hardened again. It is suitable for electrochemical machining and mirror polishing. It has good comprehensive mechanical properties and can be hardened to >40HRC.

The steel can also be nitriding, boronizing and other chemical heat treatment, the surface hardness after treatment can be increased from 370 ~420HV to 100HV significantly improve the durability and corrosion resistance of the die, can also be used for the die on the surface of chrome plating. Repair welding method can also be used to repair the mold after local damage, welding quality is good, can be processed. In the pre - hard state, prevent heat treatment deformation. The steel has been incorporated into the standard GB/T1299-2000 and YB/T 094-1997.

Chemical composition

C Mn Si Cr Mo Ni

0.28 0.40 0.60 1.00 0.20 0.80 1.40 2.00 0.30 0.55 0.80 1.20 0.020 0.015 or less or less

The phase transition points are Ac1=725℃, Ac3810℃, Ms280℃

State of supply

Pre-hardened, hardness 30HRC

Reference grade number

Chinese GB standard number 3Cr2NiMo, Swedish UDDEHOLM standard number IMPAX HI HARD, American AISI standard number P20 MODIFIED, American AISI standard number P20 + Ni, German DIN standard number 1.2738, Swedish Yisheng100 (ASSAB) Standard Grade 718 (HH)

Production process

Alkaline open furnace roughing → vacuum degassing, ladle powder refining → hydraulic forging → rough machining → ultrasonic flaw detection → tempering heat treatment → inspection factory. The steel produced by this process has high cleanliness, fine structure, good mirror polishing performance and surface roughness up to Ra0.05-0.025um.

Performance Characteristics

After quenching at 860℃ and tempering at 650℃, the mechanical properties of 3Cr2NiMo die steel at room temperature and high temperature are shown in the table below

The experimental temperature ℃ σb (MPa) σs(MPa) δ(%) ψ(%) αk(J/ cm2) HRC

Room temperature 1120 1020 16 61 96 35

200 1006 882 13.6 56 --

400 882 811 14.0 67 --