This standard is formulated by referring to more than a dozen domestic and foreign die steel technical standards, summarizing the research results of hot forging die steel in my country, and combining the current situation of my country's die steel industry. This standard specifies the technical requirements and heat treatment technical conditions of hot forging die steel. This standard is applicable to the selection and heat treatment of hot bulk forming dies. JB/T 8431-1996 Hot forging die steel and its heat treatment technical conditions JB/T8431-1996 Standard download decompression password: www.bzxz.net

JB/T 8431--96
This standard is formulated by referring to more than a dozen die steel technical standards at home and abroad, summarizing the research results of hot forging die steel in my country, and combining the current situation of my country's die steel industry.
Appendix A of this standard is the standard appendix.
Appendix B and Appendix (of this standard are suggested appendices. This standard was proposed by the National Technical Committee for Die Standardization. This standard is under the jurisdiction of the Beijing Electromechanical Research Institute of the Ministry of Machinery Industry: Drafting units of this standard: Beijing Electromechanical Research Institute, First Automobile Works, Beijing Die Factory, Huazhong University of Science and Technology Main drafters of this standard: Li Pingan, Zhang Yunian, Yang Jing, Liao Shaoji, Luo Xuexin. 197
1 Fanquan
Mechanical Industry Standard of the People's Republic of China
Hot Forging Die Steel and Its Heat Treatment
Technical Conditions
This standard specifies the technical requirements and heat treatment technical conditions for hot forging die steel. This standard applies to the material selection and heat treatment of hot bulk forming dies. 2 Referenced Standards
JB/T 8431—96
The clauses contained in the following standards constitute the clauses of this standard through reference in this standard. When this standard is published, the versions shown are valid. All standards will be revised, and parties using this standard should explore the possibility of using the latest versions of the following standards. GB 224--78 Determination of decarburization depth of steel GB 702—86
Dimensions, shapes, weights and allowable deviations of hot-rolled round and square steels Technical conditions for alloy tool steels
GB 1299—85
GB 2101--80
GB 9452-88
GB 994388
GB 10561--89
GB 11880-89
General provisions for acceptance, packaging, marking and quality certification of steel sectionsMethod for determining effective heating zone of heat treatment furnaces
Technical conditions for high-speed tool steel bars
Microscopic evaluation method for non-metallic inclusions in steelTechnical conditions for die forging hammers and large mechanical forging pressesGB/T 15824-
一1995Test method for thermal fatigue of hot working die steelJB 3814—85
JB 3877---85
Normalizing and annealing of steel
Tempering and tempering of steel
JB/T6979---93Quality grading of large and medium-sized steel forging modules (ultrasonic and inclusions) 3 categories
3.1 Hot forging die steel can be divided into three categories according to the use characteristics of the die: steel for hammer forging and large-section machine forging dies, steel for small and medium-section machine forging dies, and steel for trimming dies. The size of the large-section machine forging die should meet the requirements of L≥B≥H≥30 0mm, see Figure 1. 3.2 Hot forging die steel can be divided into three categories according to chemical composition: low alloy tool steel, alloy tool steel and high speed tool steel. L
Figure 1 Size of large section machine forging die
Approved by the Ministry of Machinery Industry of the People's Republic of China on September 3, 1996198
Implementation on July 1, 1997
4 Technical conditions for hot forging die steel
4.1 Chemical composition and refining method
JB/T 8431-96
4.1.1 The chemical composition of low alloy tool steel and alloy tool steel for hot forging die steel shall comply with the provisions of Table 3 of GB1299--85; the chemical composition of high speed tool steel shall comply with the provisions of Table 3 of GB9943-88; the chemical composition of forging hammer and large section machine forging die steel shall comply with the provisions of Table 1 of GB11880-89. The chemical composition of new hot forging die steel shall comply with the provisions of Table 1. Table 1 Chemical composition of new hot forging steel
1 |4Cr2NiMaSi
23Cr2MoWVNi
2Cr3Mo2NiVSi
4Cr3Mo2NiVNbB
4Cr3Mo2MnSiVNbB
4Cr3Mo2Mn VB
3Cr3Mo3VNb
4Cr3M03W4VNb
4Cr5Mo2Mn VSi
106Cr4Mo3Ni2WV
≤0. 030. 03
0.450.450.030.03
≤0.5≤0.03≤0.03
0. 030. 03
0.600.350.03—0.03
0.03≤0.03
0. 03-≤0. 03
≤0.40≤0.40≤0.03≤0.03
Ca proper
B trace
4.1.2 Steel can be produced by open hearth furnace, electric furnace, converter, refining outside the furnace, electroslag remelting and other smelting methods. It is recommended to use the double smelting method of open hearth furnace, electric furnace or converter smelting followed by refining outside the furnace or electroslag remelting to produce hot forging die steel. 4.2 The shape and size requirements of hot forging die steel profiles shall comply with the provisions of GB702; the shape and size requirements of forging modules shall comply with the provisions of GB11880.
4.3 The surface of hot forging die steel shall not have visible cracks, folds, scars and slag inclusions. The cross-section acid leaching low-magnification microstructure test piece shall not have visible shrinkage cavities, bubbles, cracks, inclusions, delamination and white spots. 4.4 Hot forging ring-shaped die steel forging modules need to be inspected by flaw detection. The supplier shall implement it in accordance with the provisions of GB11880 and JB/T6979. 199
JB/T8431-—96
4.5 The delivery state of hot forging die steel is annealed. The annealing hardness of low alloy tool steel is ≤241HB, and the annealing hardness of alloy tool steel and high-speed tool steel is ≤269HB.
4.6 The depth of the total decarburized layer (ferrite + transition layer) on one side of hot forging die steel is ≤(0.20 + 1.5%D)mm, where D is the nominal size of the steel section. The inspection method for decarburized layer shall comply with the provisions of GB224. 4.7 Non-metallic inclusions in hot forging die steel shall be inspected and rated using the ASTM rating chart in GB10561·89, which shall comply with the provisions of Table 2. The inspection of non-metallic inclusions in S-containing steel shall be determined by negotiation between the supply and demand parties. Table 2 Inspection and rating of non-metallic inclusions
Inclusion type
B coarse or fine or D coarse or fine
A coarse or fine or C coarse or fine
4.8 According to the requirements of the demander, additional inspections of steel grain size, fracture, mechanical properties and other items may be added. The specific requirements shall be determined by negotiation between the supply and demand parties.
4.9 The inspection of hot forging die steel shall be carried out by the supplier, and a certificate of conformity shall be provided. 4.10 The packaging, marking and quality certificate of hot forging die steel shall comply with the provisions of GB2101; the packaging, marking and quality certificate of forging modules shall comply with the provisions of GB11880. 5 Technical conditions for heat treatment of hot forging die steel 5.1 Heat treatment heating equipment can be selected from air furnaces, salt bath furnaces, protective atmosphere furnaces, vacuum furnaces, fluidized particle furnaces, etc. The specific requirements are determined by the process personnel. Anti-oxidation (decarburization) measures should be taken when heating with air medium. Vacuum furnaces, protective atmosphere furnaces, and fluidized particle furnaces should be used as much as possible for heat treatment of hot forging die steel.
5.2 The determination of the heating zone of heat treatment heating equipment shall comply with the provisions of GB9452. 5.3 Quenching media can be selected from oil, organic media, air, protective gas, hot bath, water, etc. according to the material and process requirements of steel. The quenching cooling equipment should have a circulating stirring device to ensure uniform cooling of the mold and reduce quenching stress. 5.4 All heating equipment and fire media should be regularly inspected, repaired, supplemented or replaced by dedicated personnel to ensure the accuracy and performance of the equipment, and keep relevant records.
5.5 The process personnel shall determine the heat treatment process parameters according to the physical and chemical properties of the hot forging die steel, the size and shape of the die, the performance requirements of the die, the purpose of the heat treatment and the heat treatment conditions. The common basic parameters of several new types of hot forging die steels are shown in Appendix A (Standard Appendix).
5.5.1 The normalizing and annealing process of steel shall comply with the provisions of JB3814. 5.5.2 The quenching and tempering process of steel shall comply with the provisions of JB3877. 5.5.3 The quenching heating rate of hot forging die steel shall be controlled, and the quenching preheating shall be carried out according to the provisions of Table 3. Table 3 Quenching preheating temperature
Quenching temperature
≥1000
First preheating
500~600
500~600
Second preheating
820~880
5.5.4 Hot forging die steel should be fully tempered in time after quenching. The tempering temperature, time and number of tempering times should be selected according to the steel used and the characteristics of the die.
5.6 After heat treatment, quality inspection shall be conducted by full-time personnel in accordance with the provisions of Chapter 7 of JB3814-85 and Chapter 8 of JB3877-85. 5.7 After heat treatment, hot forging die steel shall have a report. The report shall include the following contents: a) name, material, quantity and weight of the die; b) type of normalizing, annealing, quenching and tempering process; 200
c) heat treatment quality inspection results;
d) operator, year, month and day of processing.
6 Principles of material selection for hot forging die steel
JB/T8431--96
6.1 Select and use hot forging die steel according to the type and specification of forging equipment, die size, complexity of die structure, die service conditions, die failure form and batch size of die processing products. 6.2 Select and use hot forging die steel according to the principle of "meeting quality requirements, exerting material potential and economical and reasonable use of steel". Appendix B (suggestive appendix) lists the performance comparison results of several hot forging die steels, and Appendix C (suggestive appendix) lists the performance that different types of hot forging die steels should have and lists the recommended steel types. 201
4Cr2NiMoSi
Chemical composition
Chemical composition is shown in Table A1.
A1.2 Characteristics of steel
JB/T 8431—
Appendix A
Common basic parameters of several new hot forging die steels (standard appendix)
Chemical composition
It has excellent room temperature and high temperature toughness and good thermal stability and thermal fatigue performance. The comprehensive performance is better than 5CrNiMo, and it is an excellent
steel for hammer forging dies and large-section machine forging dies. A1.3 Critical point
Critical point is shown in Table A2.
Table A2 Critical point
A1.4 Forging temperature specification
Forging temperature specification see Table A3.
Heating temperature
1100～1150
A1.5 Heat treatment process
Forging temperature specification
Initial forging temperature
1050~1100
Final forging temperature
≥850
Cooling method
Furnace cooling Pit cooling
Annealing process: (820±10)C insulation for 3h, furnace cooling to 700720℃ insulation for 46h, then furnace cooling to 500℃ out of the furnace, 249HB. Quenching and tempering process: heating at 980℃, oil cooling, tempering at 650℃ twice, 38～42HRC. A2
3Cr2MoWVNi
Chemical composition
Chemical composition is shown in Table A4.
2 Characteristics of steel
Chemical composition
It has excellent room temperature and high temperature toughness, good thermal stability, thermal fatigue performance and high temperature strength. It is an excellent steel for large-section machine forging dies.
A2.3 Critical point
Critical point is shown in Table A5.
A2.4 Forging temperature specification
Forging temperature specification is shown in Table A6.
Heating temperature
1100~1150
A2.5 Heat treatment process
JB/T8431—96
Table A5 Critical point
Initial forging temperature
1060~1100
Forging temperature specification
Final forging temperature
≥850
Cooling method
Ash cooling pit cooling
Annealing process: 820℃ for 3h, furnace cooling to 700~720℃ for 4~6h, furnace cooling to 500℃, 249HB. Quenching and tempering process: heating at 980~1020℃, oil cooling, tempering twice at 610-660C, 40~50HRC. 2Cr3Mo2NiVSi
A3.1 Chemical composition
Chemical composition is shown in Table A7.
A3.2 Characteristics of steel
Chemical composition
At about 600C, it has excellent high temperature strength, oxidation resistance, thermal fatigue performance, and is a new type of hot forging die steel. A3.3 Critical point
Critical point is shown in Table A8.
Critical point
A3.4 Forging temperature specification
Forging temperature specification is shown in Table A9.
Heating temperature
1100~1150
A3.5Heat treatment process
Initial forging temperature
1000~1100
Forging temperature specification
Final forging temperature
≥850
Cooling method
Annealing process: (780±10)C for 3h, furnace cooling to 680C at a cooling rate of ≤40C/h, then cooling with the furnace, 217~220HB Quenching and tempering process: heating at 1010C, oil cooling, tempering at 400C once, 44~45HRC. A4 4Cr3Mo2NiVNbB
A4.1Chemical composition
Chemical composition is shown in Table A10.
Steel Characteristics
JB/T 8431—96
Table A10
Chemical Composition
It has excellent thermal stability, high temperature strength and thermal fatigue performance. It is a new type of hot forging die steel used under high die working temperature conditions.
A4.3 Critical Point
Critical Point See Table A11.
Table A11 Critical Point
A4.4 Forging Temperature Specification
Forging Temperature Specification See Table A12.
Table A12 Forging temperature specification
Heating temperature
1100~1150
A4.5 Heat treatment process
Initial forging temperature
1000~1100
Final forging temperature
≥900
Cooling method
Ash cold sand cold
Annealing process: (850±10)℃ for 3h, furnace cooling to (720±10)℃ for 5h, then furnace cooling, 197~217HB. Tempering process: 1130℃ heating, oil cooling, 670℃ tempering twice, 42~44HRC; 640℃ tempering twice, 47~48HRC. A54Cr3Mo2MnSiVNbB
A5.1 Chemical composition
Chemical composition is shown in Table A13.
Table A13
A5.2 Characteristics of steel
Chemical composition
It has excellent high temperature strength, thermal stability and thermal fatigue performance. It is a new type of hot forging die steel suitable for working at very high temperature.
A5.3 Critical point
Critical point is shown in Table A14.
Table A14 Critical point
A5.4 Forging temperature specification
Forging temperature specification is shown in Table A15.
Heating temperature
1100~1150
Table A15
Forging temperature specification
Initial forging temperature
1050~1100
Final forging temperature
≥900
Cooling method
A5.5 Heat treatment process
JB/T 8431-96
Annealing process: (850±10)C holding for 3h, furnace cooling to (720±10)C holding for 5h, then furnace cooling, 170~181HB, tempering process: heating at 1150C, oil cooling, tempering at 680C twice, 43~44HRC; tempering at 650C twice, 4950HRC. 4Cr3Mo2MnVB
A6.1 Chemical composition
Chemical composition is shown in Table A16.
Table A16
A6.2 Characteristics of steel
Chemical composition
It has excellent high temperature strength and thermal fatigue performance. It is a new type of hot forging die steel used at higher temperatures. A6.3 Critical point
Critical point is shown in Table A17.
Table A17 Critical point
A6.4 Forging temperature specification
Forging temperature specification is shown in Table A18.
Heating temperature
1100~1150
A6.5 Heat treatment process
Table A18
Initial forging temperature
1050～1100
Forging temperature specification
Final forging temperature
≥850
Quenching method
Ash cooling_pit cooling
Annealing process: (840±10)℃ for 3h, furnace cooling to (720±10)℃ for 5h, furnace cooling again, 180~200HBQuenching and tempering process: 1030℃ heating, oil cooling, 650~660℃ tempering twice, 42~44HRC: 600~610℃ tempering twice, 48~49HRC.
3Cr3M03VNb
A7.1 Chemical composition
Chemical composition is shown in Table A19.
Table A19
A7.2 Characteristics of steel
Chemical composition
It has excellent high temperature strength, high temperature toughness and thermal fatigue performance. It is a new type of hot forging die steel with excellent comprehensive performance. A7.3 Critical point
See Table A20 for critical point.
Table A20 Critical point
A7.4 Forging temperature specification
See Table A21 for forging temperature specification.
Heating temperature
1170~1190
A7.5 Heat treatment process
JB/T 8431--96
Table A21
Forging temperature specification
Initial forging temperature
1100~1150
Final forging temperature
Annealing process: 870℃ for 3h, furnace cooling to 710-~730℃ for 5h, then furnace cooling, 164~168HB. Cooling method
Ash cooling and sand cooling
Braid tempering process: 1080C heating, oil cooling, 620~640℃ tempering twice, 40~44HRC; 570~~600℃ tempering twice, 47~48HRC.
A84Cr3Mo3W4VNb
A8.1 Chemical composition
Chemical composition is shown in Table A22.
Table A22
A8.2 Characteristics of steel
High high temperature strength and good thermal fatigue resistance. A8.3 Critical point
Critical point is shown in Table A23.
Chemical composition
Critical point
Table A23
A8.4 Forging temperature specification
Forging temperature specification is shown in Table A24.
Heating temperature
1100~1150
A8.5Heat treatment process
Table A24
Initial forging temperature
10501100
Forging temperature specification
Final forging temperature
≥900
Cooling method
Ash cold sand cold
Annealing process: (810±10)℃ for 3h, furnace cooling to (660±10)℃ for 5h, then furnace cooling, 241～270HB. Tempering process: 1160℃ heating, oil cooling, 660℃C tempering twice, 49～50HRC. A94Cr5Mo2MnVSi
A9.1Chemical composition
Chemical composition is shown in Table A25.
Table A25
A9.2 Characteristics of steel
Chemical composition
It has excellent oxidation resistance, thermal fatigue resistance and thermal melting loss resistance, and is especially suitable for aluminum alloy die casting molds. 206
A9.3 Critical point
Critical point is shown in Table A26.
A9.4 Forging temperature specification
Forging temperature specification is shown in Table A27.
Heating temperature
1100-~1150
A9.5Heat treatment process
JB/T8431—96
Table A26
Critical point
Table A27
Forging temperature specification
Initial forging temperature
10501100
Final forging temperature
≥850
Cooling method
Gray sand cooling
Annealing process: (850±10)℃ for 3h, furnace cooling to (730±10)℃ for 5h, then furnace cooling, 180~190HB. Quenching and tempering process: heating at 1020℃, oil cooling, tempering twice at 600~610℃, 42~45HRC. A10 6Cr4M03Ni2WV
A70.1 Chemical composition
Chemical composition is shown in Table A28.
Table A28
A10.2 Characteristics of steel
Chemical composition
It has excellent high temperature strength and heat wear resistance. It is a new type of hot forging die steel with a base steel type that can be used for both hot and cold applications. A10.3 Critical point
Critical point is shown in Table A29.
Table A29
Critical point
A10.4 Forging temperature specification
Forging temperature specification is shown in Table A30.
Heating overflow
1100～~1150
A10.5 Heat treatment process
Table A30 Forging temperature specification
Initial forging temperature
1050~1100
Final forging temperature
Quenching method
Annealing process: (850±10)℃ for 3h, furnace cooling to (720±10)℃ for 5h, then furnace cooling, 170～220HB. Braid tempering process: heating at 1130℃, oil cooling, tempering at 650℃ twice, 47~48HRC. C
099009
002009002
099009
002059
2 ~s0f
0 yuan~8.68
ANASOEIE
ENAMOAE3 Critical point
Critical point see Table A26.
A9.4 Forging temperature specification
Forging temperature specification see Table A27.
Heating temperature
1100-~1150
A9.5Heat treatment process
JB/T8431—96
Table A26
Critical point
Table A27
Forging temperature specification
Initial forging temperature
10501100
Final forging temperature
≥850
Cooling method
Gray sand cooling
Annealing process: (850±10)℃ for 3h, furnace cooling to (730±10)℃ for 5h, then furnace cooling, 180~190HB. Quenching and tempering process: heating at 1020℃, oil cooling, tempering twice at 600~610℃, 42~45HRC. A10 6Cr4M03Ni2WV
A70.1 Chemical composition
Chemical composition is shown in Table A28.
Table A28
A10.2 Characteristics of steel
Chemical composition
It has excellent high temperature strength and heat wear resistance. It is a new type of hot forging die steel with a base steel type that can be used for both hot and cold applications. A10.3 Critical point
Critical point is shown in Table A29.
Table A29
Critical point
A10.4 Forging temperature specification
Forging temperature specification is shown in Table A30.
Heating overflow
1100～~1150
A10.5 Heat treatment process
Table A30 Forging temperature specification
Initial forging temperature
1050~1100
Final forging temperature
Quenching method
Annealing process: (850±10)℃ for 3h, furnace cooling to (720±10)℃ for 5h, then furnace cooling, 170～220HB. Braid tempering process: heating at 1130℃, oil cooling, tempering at 650℃ twice, 47~48HRC. C
099009
002009002
099009
002059
2 ~s0f
0 yuan~8.68
ANASOEIE
ENAMOAE3 Critical point
Critical point see Table A26.
A9.4 Forging temperature specification
Forging temperature specification see Table A27.
Heating temperature
1100-~1150
A9.5Heat treatment process
JB/T8431—96
Table A26www.bzxz.net
Critical point
Table A27
Forging temperature specification
Initial forging temperature
10501100
Final forging temperature
≥850
Cooling method
Gray sand cooling
Annealing process: (850±10)℃ for 3h, furnace cooling to (730±10)℃ for 5h, then furnace cooling, 180~190HB. Quenching and tempering process: heating at 1020℃, oil cooling, tempering twice at 600~610℃, 42~45HRC. A10 6Cr4M03Ni2WV
A70.1 Chemical composition
Chemical composition is shown in Table A28.
Table A28
A10.2 Characteristics of steel
Chemical composition
It has excellent high temperature strength and heat wear resistance. It is a new type of hot forging die steel with a base steel type that can be used for both hot and cold applications. A10.3 Critical point
Critical point is shown in Table A29.
Table A29
Critical point
A10.4 Forging temperature specification
Forging temperature specification is shown in Table A30.
Heating overflow
1100～~1150
A10.5 Heat treatment process
Table A30 Forging temperature specification
Initial forging temperature
1050~1100
Final forging temperature
Quenching method
Annealing process: (850±10)℃ for 3h, furnace cooling to (720±10)℃ for 5h, then furnace cooling, 170～220HB. Braid tempering process: heating at 1130℃, oil cooling, tempering at 650℃ twice, 47~48HRC. C
099009
002009002
099009
002059
2 ~s0f
0 yuan~8.68
ANASOEIE
ENAMOAE
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