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round bar
Round
AISI, ASTM, DIN, JIS, GB, BS
Stainless Steel Scrap
Forged
Bar
Polished
High-strength Steel Plate, Wear Resistant Steel, Silicon Steel, Cold Heading Steel, Free Cutting Steel, Mold Steel
Die Steel Bar
Smooth
Wooden
6-400mm
China
7214100000
Product Description
718/1.2738/3Cr2MnNiMo
718(3Cr2MnNiMo) steel is a new type of steel developed on the basis of P20 steel.By adding 0.8%~1.2% Ni to P20,718 steel is widely used in the international pre-hardening mold steel. Due to the effect of Ni, this steel has higher hardenability, stronger toughness and corrosion resistance than P20 steel,which could make the steel with large section size have uniform hardness distribution,good polishing performance and low surface roughness after hardening and tempering.When used to make molds,the steel is usually subjected to tempering heat treatment with hardness of 28~35HRC(that is pre-hardening) and then processed into molds before direct use,which not only ensures the performance of large and super large molds,but also avoids the mold deformation caused by heat treatment.718 steel is suitable for making super large and large plastic molds,precision plastic molds,and also can be used to make low melting point alloy(such as tin,zinc,aluminum alloy) die-casting molds.
1.Size Range for 718 Plastic Mold Steel
718 Steel Round Bar: diameter 80mm~330mm
718 Steel Plate: thickness 25mm~400mm x width 200mm~800mm
Delivery Condition:
Tured Round Bar,Milling Plate,Black,requiremts for customers.
Spheroidizing Annealing,ESR material.
2.718 Plastic Mold Steel Equivalent Grades
3. 718 Plastic Mold Steel Chemical Composition
4. 718 Plastic Mold Steel Physical Properties
Physical properties of 718 Steel are listed in the tables below.The density is 7.80g/cm3 ; Coefficient of linear thermal expansion(temperature 20~200 °C) is 12.7x10-6;and the specific heat at the constant pressure(68°F,20°C) Cp is 460J/(kg·K).
Critical temperature of 718 Steel
Elastic modulus of 718 Steel
Thermal conductivity of 718 Steel
5.Forging of 718 Plastic Mold Steel
6.Heat treatment of 718 Plastic Mold Steel
High Temperature Tempering
The steel should be heated through to 1292°F(700 °C), holding time 4 hours,cool in the furnace to below 932°F(500°C),then freely in air.
Isothermal Annealing
Protect the steel and heat through to 1562°F(850 °C), holding time 2 hours;slowly cool in the furnace to the isothermal temperature 1292°F(700 °C), holding time 4 hours, cool in the furnace to below 932°F(500°C),then freely in air.
Quenching
Heat up to the temperature 1544~1598°F(840~870 °C),cool in oil or air,hardness≥50HRC.
Tempering
The temperature of tempering is 1022~1202°F(550~650 °C),cool in air,hardness30~38HRC.
7.Mechanical Properties of 718 Plastic Mold Steel
Properties after tempering at different temperatures
Note:1562°F(850 °C) oil quenching.
Mechanical test
Note:1580°F(860 °C) oil quenching, 1202°F(650 °C) tempering.
Effect of tempering temperature on performance
Note:1580°F(860 °C) oil quenching.
8.718 Plastic Mold Steel Applications
-Injection molds for thermoplastics
-Extrusion dies for thermoplastics
-Blow molds
-Forming tools, press-brake dies (possibly flame hardened or nitrided)
-Aluminium die casting prototype dies
-Structural components, shafts
718(3Cr2MnNiMo) steel is a new type of steel developed on the basis of P20 steel.By adding 0.8%~1.2% Ni to P20,718 steel is widely used in the international pre-hardening mold steel. Due to the effect of Ni, this steel has higher hardenability, stronger toughness and corrosion resistance than P20 steel,which could make the steel with large section size have uniform hardness distribution,good polishing performance and low surface roughness after hardening and tempering.When used to make molds,the steel is usually subjected to tempering heat treatment with hardness of 28~35HRC(that is pre-hardening) and then processed into molds before direct use,which not only ensures the performance of large and super large molds,but also avoids the mold deformation caused by heat treatment.718 steel is suitable for making super large and large plastic molds,precision plastic molds,and also can be used to make low melting point alloy(such as tin,zinc,aluminum alloy) die-casting molds.
1.Size Range for 718 Plastic Mold Steel
718 Steel Round Bar: diameter 80mm~330mm
718 Steel Plate: thickness 25mm~400mm x width 200mm~800mm
Delivery Condition:
Tured Round Bar,Milling Plate,Black,requiremts for customers.
Spheroidizing Annealing,ESR material.
2.718 Plastic Mold Steel Equivalent Grades
| Country | Sweden | German | China | |
| Standard | ASSAB | W-nr. | DIN | GB/T1299-2000 |
| Grades | 718 | 1.2738 | 40CrMnNiMo8-6-4 | 3Cr2MnNiMo |
3. 718 Plastic Mold Steel Chemical Composition
| Grades | C% | Si% | Mn% | P% | S% | Cr% | Mo% | Ni% |
| 718 | 0.32~0.40 | 0.20~0.80 | 1.00~1.50 | ≤0.03 | ≤0.03 | 1.70~2.00 | 0.25~0.40 | 0.85~1.11 |
| 1.2738/40CrMnNiMo8-6-4 | 0.35~0.45 | 0.20~0.40 | 1.30~1.60 | ≤0.035 | ≤0.035 | 1.80~2.10 | 0.15~0.25 | 0.90~1.20 |
| 3Cr2MnNiMo | 0.32~0.40 | 0.20~0.80 | 1.00~1.50 | ≤0.03 | ≤0.03 | 1.70~2.00 | 0.25~0.40 | 0.85~1.15 |
Physical properties of 718 Steel are listed in the tables below.The density is 7.80g/cm3 ; Coefficient of linear thermal expansion(temperature 20~200 °C) is 12.7x10-6;and the specific heat at the constant pressure(68°F,20°C) Cp is 460J/(kg·K).
Critical temperature of 718 Steel
| Critical point | Ac1 | Ac3 |
| Temperature(approximation) | 1319°F(715°C) | 1418°F(770°C) |
| Temperature /°C | 20 | 200 |
| E/MPa | 205000 | 200000 |
| Temperature /°C | 20 | 200 |
| λ/W•(m•K)-1 | 29.0 | 29.5 |
| Heating temperature | Starting forging temperature | Final forging temperature | Cooling |
| 2084~2156°F (1140~1180°C) | 1922~2084°F (1050~1140°C) | ≥1562°F (≥850°C) | Cooling in hole |
High Temperature Tempering
The steel should be heated through to 1292°F(700 °C), holding time 4 hours,cool in the furnace to below 932°F(500°C),then freely in air.
Isothermal Annealing
Protect the steel and heat through to 1562°F(850 °C), holding time 2 hours;slowly cool in the furnace to the isothermal temperature 1292°F(700 °C), holding time 4 hours, cool in the furnace to below 932°F(500°C),then freely in air.
Quenching
Heat up to the temperature 1544~1598°F(840~870 °C),cool in oil or air,hardness≥50HRC.
Tempering
The temperature of tempering is 1022~1202°F(550~650 °C),cool in air,hardness30~38HRC.
7.Mechanical Properties of 718 Plastic Mold Steel
Properties after tempering at different temperatures
| Tempering temperature | 100 | 200 | 300 | 400 | 500 | 600 | 700 |
| Hardness(HRC) | 51 | 50 | 48 | 46 | 42 | 36 | 28 |
| Tensile strengthσb/MPa | 1730 | 1670 | 1570 | 1480 | 1230 | 1140 | 920 |
Mechanical test
| Test temperature | σb/MPa | σs/MPa | δ(%) | ψ(%) | aK/J·cm-2 | Hardness(HRC) |
| Room temperature | 1120 | 1020 | 16 | 61 | 96 | 35 |
| 392°F(200 °C) | 1006 | 882 | 13.6 | 56 | -- | -- |
| 752°F(400 °C) | 882 | 811 | 14.0 | 67 | -- | -- |
Effect of tempering temperature on performance
| Tempering temperature | Hardness(HRC) | σb/MPa | σs/MPa | δ5(%) | ψ(%) | aK/J·cm-2 |
| 842°F(450 °C) | 45 | 1600 | 1300 | 12 | 52 | 40 |
| 932°F(500 °C) | 42 | 1400 | 1250 | 13 | 53 | 50 |
| 1022°F(550 °C) | 38 | 1300 | 1150 | 14 | 60 | 70 |
| 1112°F(600 °C) | 36 | 1200 | 900 | 15 | 65 | 120 |
| 1202°F(650°C) | 32 | 900 | 750 | 16 | 67 | 160 |
| 1292°F(700 °C) | 26 | 700 | 650 | 17 | 67 | 190 |
8.718 Plastic Mold Steel Applications
-Injection molds for thermoplastics
-Extrusion dies for thermoplastics
-Blow molds
-Forming tools, press-brake dies (possibly flame hardened or nitrided)
-Aluminium die casting prototype dies
-Structural components, shafts
