1. Main application:
Large, precision, high polishing plastic moulds, such as car accessories, household appliance, electronic and Audio/Video products.
2. Manufacturers:
An Steel, Tai Steel, Wuyang Steel, Wuhan Steel, Fushun Steel, etc.
3. Delivery conditions:
Conventional or ESR, hot rolling or forging, black surface or milling
Hardened and tempered to: 28~35HRC
4. General
In the DIN EN ISO 4957 the grades 1.2311 (AISI P20), 1.2312 (AISI P20+S) and 1.2738 (AISI P20+Ni) covered by the above mentioned code were amalgamated. The grade 1.2738 contain additional quantities of Ni and no additional quantities of S.
5. Chemical analysis:
|
C%
|
Mn%
|
Si%
|
Cr%
|
Ni%
|
Mo%
|
P%
|
S%
|
|
0.32~0.40
|
1.10~1.50
|
0.20~0.40
|
1.10~2.00
|
2.90~3.50
|
0.25~0.40
|
=<0.03
|
=<0.03
|
6. Mechanical properties:
Low sulphur plastic mould steel that is usually supplied in a quenched and tempered condition. The additional Ni content improves the through hardenability large dimensions (>400 mm). Good machinability, better polishability compared to 1.2312 (AISI P20+S). Similar to AISI P20+Ni.
7. Available sizes:
Round Bar: Φ 6-410mm
Flat: 8-160*205-710mm
Plate: 20-400mm*1800-3200mm (Thickness*Width)
Mould: 200*200-1200*1000mm
Length: 3000-12000mm
Mill deliver conditions, or sawing or cutting for customer request.
8. Compared grades:
|
Chinese
|
American
|
German
|
Swedish
|
Japanese
|
DIN EN
|
|
GB
|
AISI
|
DIN
|
ASSAB
|
JIS
|
ISO 4957
|
|
3CrMnNiMo
|
P20+Ni
|
1.2738
|
718
|
NAKS5
|
40CrMnNiMo8-6-4
|
|
Grade
|
Standard
|
C
|
Si
|
Mn
|
Cr
|
Mo
|
Ni
|
P、S≤
|
|
718
|
ASSAB
|
0.32-0.40
|
0.20-0.40
|
1.10-1.50
|
1.70-2.00
|
0.25-0.40
|
0.85-1.15
|
0.030
|
|
1.2738
|
DIN
|
0.35-0.45
|
0.20-0.40
|
1.30-1.60
|
1.80-2.10
|
0.15-0.25
|
0.90-1.20
|
0.030
|
|
3Cr2MnNiMo
|
GB
|
0.32-0.40
|
0.20-0.40
|
1.10-1.50
|
1.70-2.00
|
0.25-0.40
|
0.85-1.15
|
0.030
|
9. Physical properties:
|
Thermal expansion coefficient
|
10-6 m
|
20-100°C
|
20-200°C
|
20-300°C
|
20-400°C
|
|
m K
|
11.8
|
12.5
|
13.1
|
13.3
|
|
|
Thermal conductivity
|
W
|
20°C
|
350°C
|
|
|
|
m K
|
39.5
|
39.1
|
|
|
10. Heat treatment:
|
Soft annealing
|
Temperature
|
Cooling
|
Hardness
|
|
710 - 740°C
|
furnace
|
max. 235 HB
|
|
|
|
|||
|
Stress relief annealing
|
Temperature
|
Cooling
|
|
|
500 - 550°C
|
furnace
|
|
|
|
|
|||
|
Hardening
|
Temperature
|
Cooling
|
Tempering
|
|
830 - 870°C
|
oil or hot bath
180 - 220°C
|
see tempering
diagram
|
|
