718/1.2738/3Cr2MnNiMo Plastic Mould Steel P20+Ni Forged and Rolled

• Customization: Available
• Type: Round
• Standard: AISI, ASTM, DIN, JIS, GB, BS
• Model NO.: round bar
• Composition: Stainless Steel Scrap
• Technique: Forged
• Shape: Bar
• Surface Treatment: Polished
• Special Use: High-strength Steel Plate, Wear Resistant Steel, Silicon Steel, Cold Heading Steel, Free Cutting Steel, Mold Steel
• Application: Die Steel Bar
• Transport Package: Wooden
• Specification: 6-400mm
• Trademark: Smooth
• Origin: China
• HS Code: 7214100000
• Production Capacity: 5000 Ton/Year

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

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

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

Critical point	Ac1	Ac3
Temperature(approximation)	1319°F(715°C)	1418°F(770°C)

Elastic modulus of 718 Steel

Temperature /°C	20	200
E/MPa	205000	200000

Thermal conductivity of 718 Steel

Temperature /°C	20	200
λ/W•(m•K)^-1	29.0	29.5

5.Forging of 718 Plastic Mold Steel

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

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

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

Note:1562°F(850 °C) oil quenching.
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	--	--

Note:1580°F(860 °C) oil quenching, 1202°F(650 °C) tempering.
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

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