CN102747203B - Heat treatment method for 5CrNiMo forging die - Google Patents

Abstract

The invention discloses a heat treatment method for a 5CrNiMo forging die. The method comprises the steps of conducting furnace heating on the 5CrNiMo forging die subjected to isothermal annealing to a temperature of 880-890 DEG C and conducting high-temperature thermal insulation at the temperature; drawing the die out of the furnace, cooling the die to a temperature of 770-790 DEG C by air, cooling the die to a temperature of 180-200 DEG C by oil, and then cooling the die to the room temperature by air; and then, heating to a temperature of 180-200 DEG C, conducting isothermal thermal insulation, and cooling the die to the room temperature by oil. According to the method, simple adjustment of a heat treatment process is conducted, the abrasive resistance of the 5CrNiMo forging die is effectively improved, and the service life of the forging die is prolonged.

Description

The heat treating method of 5CrNiMo forging die

Technical field

The present invention relates to the thermal treatment process of forging die, be specifically related to the heat treating method of 5CrNiMo forging die.

Background technology

5CrNiMo is the Hot Die Steel that usage quantity is larger, has formed aborning the thermal treatment process of comparative maturity.Because 5CrNiMo hot-forging die can bear huge impact load in Working environment, in heating and cooling process repeatedly, can be caused inhomogeneous thermal stresses and thermal strain, bear the friction of flow red-hot metal and mold cavity surface simultaneously, therefore its work-ing life shorter, often produce burst apart, subside, the failure phenomenon such as wearing and tearing, thermal fatigue.The main failure forms of forging die is to burst apart and die cavity wearing and tearing, this is because the toughness of hot-forging die is not enough, and the wear resistance on forging die cavity surface is on the low side to be caused.Analysis shows, thermal treatment is improper is the major cause that causes the toughness deficiency of hot-forging die.Therefore,, in order to improve fracture toughness property and the wear resistance of forging die, to extend the work-ing life of mould, be badly in need of a kind of new thermal treatment process of exploitation.

Summary of the invention

The object of the invention is to, for existing hot-forging die short problem in work-ing life, provides a kind of heat treating method of 5CrNiMo forging die, and the method can effectively extend the work-ing life of forging die.

To achieve these goals, the invention provides a kind of heat treating method of 5CrNiMo forging die, comprise the following steps:

5CrNiMo forging die after isothermal annealing is heated to 880-890 ℃ with stove, at this temperature, carries out soak;

Then come out of the stove air cooling to 770-790 ℃, then oil cooling is to air cooling after 180-200 ℃ to room temperature;

Subsequently, be heated to the 180-200 ℃ of rear oil cooling of isothermal insulation to room temperature.

Preferably, described isothermal annealed temperature is 660-680 ℃, and the time is 3-5h.

Preferably, the time of described soak is 2-3h.

Preferably, the time of described isothermal insulation is 4-6h.

The present invention, by thermal treatment process is simply adjusted, has effectively improved toughness and the wear resistance thereof of 5CrNiMo forging die, has extended the work-ing life of forging die, has improved economic benefit.

Embodiment

Below in conjunction with specific embodiment, further describe content of the present invention.

Embodiment 1

After 5CrNiMo forging die is heated to 660 ℃, be incubated 5h, reheat to 880 ℃ of insulation 3h; Then the air cooling to 770 ℃ of coming out of the stove, then after oil cooling to 180 ℃ air cooling to room temperature; Subsequently, be heated to 200 ℃ insulation 5h after oil cooling to room temperature.

Embodiment 2

After 5CrNiMo forging die is heated to 670 ℃, be incubated 4h, reheat to 890 ℃ of insulation 2h; Then the air cooling to 780 ℃ of coming out of the stove, then after oil cooling to 195 ℃ air cooling to room temperature; Subsequently, be heated to 180 ℃ insulation 4h after oil cooling to room temperature.

Embodiment 3

After 5CrNiMo forging die is heated to 680 ℃, be incubated 3h, reheat to 885 ℃ of insulation 2.5h; Then the air cooling to 790 ℃ of coming out of the stove, then after oil cooling to 200 ℃ air cooling to room temperature; Subsequently, be heated to 190 ℃ insulation 6h after oil cooling to room temperature.

Embodiment 4

After 5CrNiMo forging die is heated to 675 ℃, be incubated 4.5h, reheat to 890 ℃ of insulation 3h; Then the air cooling to 785 ℃ of coming out of the stove, then after oil cooling to 190 ℃ air cooling to room temperature; Subsequently, be heated to 195 ℃ insulation 5.5h after oil cooling to room temperature.

Comparative example

After 5CrNiMo forging die is heated to 650 ℃, be incubated 2h, reheat to 900 ℃ of insulation 4h; Then the air cooling to 780 ℃ of coming out of the stove, after oil cooling to 150 ℃, be heated to 250 ℃ of insulation 3h after oil cooling to room temperature.

Table 1 has provided the test result in the work-ing life that adopts the 5CrNiMo forging die that different heat treatment technique obtains.Testing method is for adopting respectively above embodiment and comparative example to process the 5CrNiMo forging die obtaining, open die forging, impressing forging wheel blank on 3000kN friction press, average wheel blank of every 8 die forging in second, die forging final forging temperature is 850-870 ℃, after one of every forging, on mold cavity surface, smear aqueous graphite as the lubricant refrigerant of holding concurrently, be 5 seconds cooling time.

The work-ing life of the 5CrNiMo forging die that table 1 employing different heat treatment technique obtains

	Embodiment 1	Embodiment 2	Embodiment 3	Embodiment 4	Comparative example
						Access times/time	6980	7202	7039	7183	4531

As known from Table 1, adopting the access times of 5CrNiMo forging die prepared by thermal treatment process of the present invention is 7000 left and right, and mould mean lifetime improves more than 55% compared with forging mould.

Claims (1)

1. a heat treating method for 5CrNiMo forging die, comprises the following steps:

5CrNiMo forging die after isothermal annealing is heated to 880-890 ℃ with stove, at this temperature, carries out soak;

Then come out of the stove air cooling to 770-790 ℃, then oil cooling is to air cooling after 180-200 ℃ to room temperature;

Subsequently, be heated to the 180-200 ℃ of rear oil cooling of isothermal insulation to room temperature;

Wherein, described isothermal annealed temperature is 660-680 ℃, and the time is 3-5h; The time of described soak is 2-3h; The time of described isothermal insulation is 4-6h.