Heat Treatment of 2311 Die Steel

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2311 die steel is the steel grade of DIN material standard in Germany. The material has excellent mechanical properties and good machinability. It is mainly used in the processing and production of plastic mould in hot working die. The material has been pre-hardened when it leaves the factory by special processing technology, which reduces the heat treatment process in normal die processing and production, and improves the economic benefits.

Name of material: GS-2311
Standard: AISI-p20 GS-2311 ASSAB-618
Usage method:
GS-2311 has been pre-hardened to 285-330HB (30-36HRC), which is similar to Sweden’s 618 German GS-2311. It can be directly used in die-making process and has good dimensional stability. Only the pre-hardened steel can meet the general needs, and the die life can reach 50W dies.

2311 die steel 2311 pre-hardened plastic die steel, after heat treatment, processing and polishing performance is good, more suitable for EDM. It can be used to manufacture large plastic moulds and moulds.

Pre-hardening to 980-1080N/mm, (30-34HRC) steel characteristics: this steel is P20 plus 1.1% nickel, steel surface to center hardness uniform, good cutting, excellent spark machine and polishing performance, suitable for gasification, hard chromium plating and titanium plating. Usage: Suitable for high requirements of plastic moulds, especially for moulds over 400 MM thick. Annealing: 720-740 C thermal insulation enough time, then with the furnace cooling to 600 C, and then cooling in the air, the hardness obtained is about 240HB (the highest). Stress relief: Heating to 600 C for about 2 hours in the protective gas furnace, then cooling slowly with the furnace. Quenching: Quenching oil after heat preservation at 840-860 or air cooling after heat preservation at 860-880 is slightly higher than instant tempering at room temperature. The hardness obtained is about 54HRC. Tempering: Tempering immediately after quenching, not less than 2-2.5 hours, and then out of the furnace air-cooled. Forging: cooling annealing in furnace at 1050-850 and air cooling at 850-900 C.

GS2311 steel is Germany (SAARSTAHL) super high quality hard plastic die steel, pre-hardened, after calcification, vacuum degassing and heat treatment, machinability and polishing performance is good, more suitable for EDM.

Characteristics of 2311 die steel:
Good polishing performance, good processability, excellent strength and toughness, can be nitrided or chromium plating.
Vacuum degassing refining treatment of pure steel, suitable for polishing or etching processing of plastic moulds.
Pre-hardening supply, without heat treatment can be directly used for die processing, shorten the construction period.
After forging and rolling, the structure is compact, 100% ultrasonic inspection, no air hole, pinhole defect.

Technical Specification for 2311 Die Steel:
Hot working
The heating temperature ranges from 1050 850 C.
annealing
The annealing temperature ranges from 850 900 C and the outlet air-cooled.
Softening annealing
The annealing temperature ranges from 710 740 C, and the holding time is determined by 1 hour of wall thickness every 25 mm.
Stress Removal Treatment
The heating temperature is 600 C (annealing state) and 550 C (quenching and tempering state). The holding time is determined according to the wall thickness of every 50mm for 1h. After holding, it is cooled with the furnace.
Quenching and tempering
The preheating temperature is 500 – 600 C, the quenching temperature is 840 – 880 C, and the heat preservation is 30 minutes (the die must be quenched in a protective atmosphere to avoid oxidation and decarbonization). Oil-cooled, cooled to 50-70 degrees C, temper immediately.
Tempering holding time is determined by workpiece thickness every 25 mm time 1 hour, at least 2 hours. Tempering temperature 180 C/200 C/.
The hardness is 52HRC/51HRC/48 HRC/46HRC/42HRC/34HRC.
Flame induction hardening
The steel can be hardened to 50HRC by flame or induction hardening, and air-cooled after hardening. General quenching medium can be used for small die. Tempering should be done immediately after hardening. Tempering temperature is 180~200 C.
Nitriding criterion
Nitriding temperature and time: 525 C 20h, the thickness of nitriding layer is 0.30mm; 525 C 30h, the thickness of nitriding layer is 0.35mm; 525 C 50h, the thickness of nitriding layer is 0.50mm.
Soft nitriding treatment
The hardness of the die surface is about 700 HV and the depth of nitriding layer is about 0.1 mm.

Use of 2311 Die Steel:
Thermoplastic injection mold, extrusion mold.
Thermoplastic blow moulds.
Main parts of heavy duty die.
Cold structural parts.
It is often used to make TV case, washing machine, refrigerator case, bucket and so on.

Specification for Heat Treatment of 2311 Die Steel:
Hardened treatment
In order to improve the service life of the die more than 800,000 die times, the hardening method of quenching and low temperature tempering can be applied to the pre-hardened steel. The heat is preheated at 500-600 centigrade for 2-4 hours, then heat preservation at 850-880 C for a certain time (at least 2 hours), and the oil is cooled to 50-100 centigrade for air cooling. The hardness is up to 50-52HRC after quenching. In order to prevent cracking, it should be treated at low temperature at low temperature at 200 centigrade. After tempering, the hardness can be kept above 48HRC.
Nitriding treatment
The surface microstructure of high hardness can be obtained by nitriding. The life of 650-700HV (57-60HRC) die after nitriding can reach more than 1 million times. The nitriding layer has a compact structure and smooth characteristics, the mold release and the corrosion resistance of wet air and alkaline solution are improved.

Chemical composition:
C:0.35-0.45
Si:0.2-0.4
Mn:1.3-1.6
Cr:1.8-2.1
Mo:0.15-0.25
S: = 0.035
P: = 0.035

Mechanical property:
Steel annealing hardness to nitride is less than or equal to 235HB

Material properties:
Physical properties:
(hardness 340HBW, at room temperature and high temperature conditions)
1) the temperature of 20 DEG C/200 DEG C/400 DEG C, density of 7. 8g/cm/7.75g/cm/7. 7g/cm.
2) C/20 ~400 temperature 20~200 DEG C, linear expansion coefficient: 12.6 * 10K/13.5 * 10K.
3) the temperature of 20 DEG C/200 DEG C/400 DEG C, the thermal conductivity of 29.0W (m, K) – /29.5W (M – K) – /31.0W (M – K)
4) the temperature of 20 DEG C/200 DEG C/400 DEG C, elastic modulus: 205000MPa/200000MPa/185000MPa
Mechanical properties:
(340HBW hardness)
1) the temperature of 20 DEG C/200 DEG C/400 DEG C, the tensile strength of 1100MPa/1050MP

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