Today, die steel will give you a comprehensive introduction to the heat treatment specifications of W18Cr4V. Of course, if you have other questions or questions about the heat treatment of W18Cr4V high-speed steel, you can leave a message on the following message board, our technical customer service will answer you in the first time.
Softening annealing specification
The annealing temperature is 860~880℃, the heat preservation is 2h, and then the cooling speed is 20~30℃/h with the furnace to (750±10) ℃×2~3h, and the slow cooling is ≦650℃, and the oven is air-cooled. Hardness ≤ 255HBW before treatment, hardness ≤ 229HBW after treatment.
General annealing code
840~860℃×2~3h, cooling at a cooling rate of 20~30℃/h to 730℃×5~6h isothermal, with the furnace cooling of 500~600℃, air cooling. The annealing cycle is very long, with a time of 20~40h or 10~25h.
Specification for isothermal spheroidizing annealing
850~870℃×3~4h, furnace cooling 740~760℃×4~5h, hardness ≦241HBW, eutectic carbide grade ≦3.
Isothermal annealing specification
Annealing temperature 860~880℃, heat preservation for 2h, furnace cooling to 740~760℃, heat preservation for 2~4h, furnace cooling to 500~600℃, air cooling, hardness ≦255HBW.
Rapid annealing specification
With the furnace heating to 600~650℃, the workpiece continues to rise to 880~900℃ at the heating speed of 20~40℃/h, the heat preservation of 0.1~0.3h, and then the cooling speed of 40~60℃/h the furnace is cooled to 780~800℃, and then the cooling speed of 30~40℃/h the furnace is cooled to 600~650℃, and the air is cooled.
Rapid annealing can replace the conventional annealing process for high speed steel casting blanks, welding blanks and repair tools before quenching annealing, significantly shorten the heat treatment cycle, reduce energy consumption, and increase the service life of tools by 20%~30%.
Cycle annealing specification
The upper limit of annealing temperature is 840℃, the lower limit of annealing is 680℃, after three cycles of annealing. When the diameter of the steel rod is ∮20mm, the heating time is 10min.
Cyclic annealing can replace ordinary isothermal annealing, pre-heat treatment of die blanks can shorten the heating and holding time, refine austenitic grains, improve the structure, improve the strength and toughness of steel and the strength of high-speed steel welding tools, which is conducive to eliminating quenching overheating, preventing abnormal grain growth and forming naphthalene structure, which is conducive to reducing quenching deformation and improving performance.
Oil toughness treatment specification
After annealing, heating (740±10) ℃, tempering oil cold, hardness 100HRB, impact toughness 21.2J/cm².
General quenching, tempering specification
Quenching temperature 1200~1240℃, oil cold, hardness ≧60HRC, tempering temperature 560~580℃.
Specification for quenching and tempering of die steel
Preheating temperature 850℃, holding time 24s/mm, quenching temperature 1260~1300℃, holding time 12~15s/mm, oil cooling, tempering temperature 560℃, tempering three times, each time 1h, air cooling, hardening, tempering hardness ≧62.
When used as cold work die steel, the quenching temperature is 1200~1240℃, and the holding time is 15~20s/mm.
Specification for low temperature quenching and tempering
Preheating temperature: The first low temperature (560±10) ℃, the second medium temperature 800~850℃, transferred to high temperature salt bath heating, heating temperature 1250~1260℃, heating time is calculated by 10s/mm, after insulation into (280±30) ℃ saltpeater bath, stay 2~5min, air cooling to room temperature, and then at (560±10) ℃ continuous tempering three times. Each time 1.5~2h, hardness 62~64HRC.
Vacuum quenching, tempering specification
1) Preheating temperature: 500~600℃ for the first time, 800~850℃ for the second time, vacuum degree 0.1Pa, quenching temperature 1000~1100℃, vacuum degree 1~10Pa. Oil or N² gas cooling, tempering temperature 180~220℃, hardness 58~62HRC.
2) Preheating temperature: 500~550℃ for the first time, 800~820℃ for the second time, vacuum 0.1Pa, quenching temperature 1240~1300℃, vacuum 1~10Pa, oil or N² gas cooling, tempering temperature 540~600℃, hardness 62~66HRC.
Specification for gas nitriding and gas nitriding carburizing
1) Technical requirements: hardness >1000HV, penetration layer depth 0.03~0.05mm, nitriding temperature 540℃, gas ratio: ammonia 30%, carrier gas (RX gas) 70%, ammonia decomposition rate 30%~40%, holding time 3h. For cold extrusion die, punch die.
2) Technical requirements: hardness >1000HV, penetration depth 0.05~0.07mm, nitriding temperature 540℃, gas ratio: ammonia 40%. Carrier gas (RX gas) 50%, ammonia decomposition rate 30%~40%, holding time 5h. For drawing die, bending die.
Gas nitrocarburizing + dehydrogenation treatment
1) Mold nitrogen carburizing was carried out in RJJ-35-9T well electric furnace: 560℃×4.5~5.0h, NH³0.45~0.6m³/h, methanol 60~70 drops /min, oil cooling.
2) Dehydrogenation treatment: 250~300℃×2h, nitrocarburizing layer depth ≧0.08mm, surface hardness 950HV0.1, core hardness 60~62HRC.
Cold extrusion punch high temperature, isothermal quenching + high temperature tempering specification
Preheating temperature 800~850℃, holding time 8min, quenching temperature (1260±5) ℃, holding time 4min, graded quenching, (280±10) ℃×3h isothermal quenching treatment; (560±10) ℃×90min×3 times tempering, air cooling.
Recommended process for rolling wire die
For preheating at 840~860℃, the holding time is calculated as 40s/mm; for heating at 1220~1240℃, the heating time is calculated as 20s/mm. It was graded at 580~620℃ (calculated at 20s/mm), then isothermal at 260~280℃ for 2.5h, and tempered at 580~585℃×1h+550℃×1h×2 times. Hardness 61~62HRC.
Specification for heat treatment for strengthening and toughening
600℃ preheating, 840~860℃ preheating, the holding time is calculated by 30s/mm; 1200℃ heating, heating time according to 8~15s/mm calculation. 550~570℃ isothermal (calculated at 30s/mm), air cooling, 550℃×1h×3 times tempering. Hardness 59~61HRC.
Isothermal quenching of bainite
Pre-heating at 810~830℃, the holding time is calculated according to 20s/mm, 1230~1250℃, the heating time is calculated according to 10~15s/mm; Quench into a salt bath at 810~830℃ for 5~8s, isothermal at 260~300℃ for 3h, air cooling to room temperature, (560±10) ℃×1.5h×4 times tempering. Hardness 62HRC.
Low temperature quenching + high temperature tempering
850~860℃ preheating, holding time calculated by 30~40s/mm, salt bath furnace heating, quenching temperature 1240~1250℃, holding time calculated by 6~10s/mm, salt bath cooling temperature 580~620℃, holding 2h, 580~590℃×1h, 550℃×1h×2 times tempering. Hardness 62~62.5HRC.
Punching die carburizing quenching specification
Charcoal with a grain size of 5~10mm is selected and Na²CO³ is added (the ratio of charcoal to Na²CO³ is 9:1).
Mix thoroughly, insert the die directly into the carburizing box, seal it, put it into the furnace at 500℃, heat it up to 820℃ for 1h, and then heat it up to 1000℃ for 2h.
Finally, it is heated to 1150~1160 ° C, short-term insulation, quenching hot oil into the box, and getting out of the oven at about 200 ° C (mastering the workpiece can only smoke and not burn when the oil is out), and tempering three times at 560 ° C for 90 minutes.
