CN101748251A - Forging method of Cr12MoV cold work die steel module - Google Patents

Abstract

The invention discloses a forging method of a Cr12MoV cold work die steel module, belonging to a forging and producing method of Cr12 type moulding steel in the metallurgy industry and die industry. The forging method comprises the following steps of: (1) heating homogeneity: heating a forging stock to 700-800 DEG C, keeping the temperature for 1-2 h, raising the temperature to 1190-1220 DEG C with the temperature raising speed of 50-100 DEG C/h, keeping the temperature for 2-3 h, and turning over the forging stock in the period of keeping the temperature to reduce the temperature difference between the front side and the back side of the forging stock; (2) forging and deforming: repeatedly tampering and pulling for 4-5 times with the forging starting temperature of 1190-1220 DEG C and the forging ending temperature of 900-950 DEG C to enable the forging ratio to be greater than 8; and (3) cooling after forging. The invention does not need technology alteration and has no limit to the forging deformation and the size of a forge piece. By adopting the invention, the finished product ratio of the forge piece reaches more than 95 percent, and the service life of a mould manufactured by using the forge piece is at least doubled compared with that of a traditional mould.

Description

A kind of forging method of Cr12MoV cold work die steel module

Technical field

The present invention relates to the forging production method of metallurgy industry and die industry Cr12 type worker mould steel, especially a kind of forging method of Cr12MoV cold work die steel module.

Background technology

The Cr12MoV cold-work die steel can not only bear heavier load, also has high wear resistance, the while low price, therefore be widely used in making moulding stock such as cold-punching mould, cold heading die, cold extruding die, wortle, thread rolling die, but also be used to make the molding roller of stainless steel and non-ferrous metal.

The basic cast structure of Cr12MoV is the ledeburite+martensitic matrix along casting crystal boundary net distribution.In forging process, if Heating temperature is too high, ledeburite melts, and becomes liquid, causes the material burning, can not forging molding.Present Forge Heating temperature is generally below 1150 ℃, be that ledeburite+austenite two-phase region forges, but because netted ledeburite contains a large amount of brittle carbides, cause forging deformation cracking easily, thereby extremely difficult forging molding, the key reason that is to say extremely difficult forging molding is the carbide in the ledeburite of net distribution, under this forging temperature, matrix is the higher austenite of plasticity, is the very big carbide of fragility around these austenite particulate, is difficult to forging molding so naturally.Its yield rate of the forging of moulding is very low in this way, though moulding do not pass through sufficient forging deformation yet, that is to say that the net distribution form of ledeburite does not have wide variation, so the tool and mould of producing with this forging is very low naturally work-ing life.According to investigations, the forging of domestic Cr12MoV steel and processing mold manufacturing factory, all exist and forge modification difficulty and tool and mould short these two difficult problems in work-ing life, tool and mould work-ing life is short then to cause that distribution of carbides is inhomogeneous to be caused owing to forge the modification difficulty, so the forging deformation difficulty becomes the concrete bottleneck of using of Cr12MoV cold-work die steel.

By the authorization of " special steel press working " editorial board of country, by Xue Yide, high high " special steel press working " book (metallurgical industry press of writing, Beijing, publish in June, 2000), be the authoritative reference book of China's special steel press working, 174～185 pages state clearly in the book, because MO, V content in the Cr12MoV steel are seldom, do not influence its forgeability, 1140 ℃ of the maximum heating temperatures of Cr12 shaped steel.Also there are 1150 ℃ of examples of the highest Forge Heating temperature of use in China, as in " failure analysis of screw thread thread rolling die and forging and intensive treatment " (Wang Rongbin, " mould manufacturing ", in June, 2004, the 6th phase, 59-62 page or leaf) record being arranged.Find out thus, in this area, the Forge Heating temperature of Cr12MoV cold-work die steel is all thought carrying out below 1150 ℃.

Country such as Japan, Germany, France uses special-purpose forging equipment, Russia is except that using special forging equipment, also use the super method for forging and molding of moulding to solve this problem of forging deformation difficulty, therefore not only moulding is regular for external Cr12MoV forging of producing or tool and mould, and be several times to tens times of home products work-ing life, but these special forging equipment investment costs are big, and the super forging method of moulding is difficult to grasp, and are unfavorable for the processing of the domestic Cr12MoV of Steel Plant cold-work die steel.

Summary of the invention

The object of the present invention is to provide and a kind ofly can thoroughly eliminate the harm of carbide network forgeability, make forging can carry out abundant forging deformation, the carbide unevenness of material is brought up to below 2 grades by the 5-8 level before forging, improve the work-ing life of tool and mould, the forging method of the Cr12MoV cold work die steel module that reduces production costs.

For reaching above purpose, the technical solution adopted in the present invention is: the forging method of this a kind of Cr12MoV cold work die steel module is characterized in that: it may further comprise the steps:

(1), add thermally homogenising: forging stock is warmed up to 700 ℃-800 ℃ with stove, is incubated 1-2 hour, again with the heat-up rate of 50-100 ℃/h, is warming up to 1190 ℃-1220 ℃, is incubated 2-3 hour, between soak base substrate is stood up, to reduce the male and female face temperature head;

(2), forging deformation: open and forge 1190 ℃-1220 ℃ of temperature, 900 ℃-950 ℃ of final forging temperatures, upsetting pull is 4-5 time repeatedly, make forging ratio＞8, when the forging temperature is lower than 900 ℃ of-950 ℃ of scopes, be heated 1190 ℃-1220 ℃ again, be incubated and forge again after 2-3 hour;

(3), forge postcooling: the cooling rate with 30 ℃/h is cooled to 100 ℃ with forging.

Adopt traditional forging method, when Forge Heating temperature during less than 1190 ℃, this steel is ledeburite and austenitic duplex structure; When Forge Heating temperature during greater than 1220 ℃, this steel is the duplex structure of austenite and liquid, and in these humidity provinces heating, distribution of carbides is inhomogeneous, has caused the forge scrap rate greater than 10%, and the work-ing life of having reduced this steel die.Adopt the present invention, when the Forge Heating temperature is 1190～1220 ℃, the Cr12MoV steel becomes the austenite one phase tissue, forging deformation plasticity is the highest, the forging Key Quality Indicator, it is the 1-2 level that the carbide unevenness can reach the GB14979-1994 standard code, distribution of carbides is the most even, test and fully to be confirmed by hot-stage microscope test and actual the forging, thereby broken form in this area the Forge Heating temperature of Cr12MoV cold-work die steel is not higher than 1150 ℃ understanding, make the performance that adopts the Cr12MoV cold work die steel module that the present invention produces that the raising of matter arranged.

Beneficial effect of the present invention is: investment need not to undergo technological transformation, to forging deformation amount and forging ' s block dimension without limits, the yield rate of forging can reach more than 95%, compare with the tool and mould of traditional forging manufacturing work-ing life with the tool and mould of this forging manufacturing and to improve 1 times at least, reduce the production cost of enterprise, improved economic benefit.

Description of drawings

Fig. 1 is distribution of carbides figure before embodiments of the invention 3 are forged, and is 8 grades by the GB14979-1994 standard rating.

Fig. 2 is that embodiments of the invention 3 are forged back distribution of carbides figure, is 2 grades by the GB14979-1994 standard rating.

Embodiment

Example example 1:

Use the present invention, the Cr12MoV cold-work die steel casting of forging 60 * 60 * 150mm and 200 * 200 * 200mm, it may further comprise the steps::

(1), add thermally homogenising: forging stock is warming up to 700 ℃ with stove, is incubated 1 hour; With the heat-up rate of 95 ℃/h, be warming up to 1190 ℃ again, be incubated 2 hours, between soak forging stock is stood up 2 times;

(2), forging deformation: open and forge 1190 ℃ of temperature, 900 ℃ of final forging temperatures, upsetting pull is 4 times repeatedly, makes forging ratio＞8, when 900 ℃ of forging temperature, is heated to 1190 ℃ again, is incubated after 2 hours, forges again;

(3), forge postcooling: the cooling rate with 30 ℃/h is cooled to 100 ℃ with forging.

Through the finished product that aforesaid method obtains, through check, this finished product forging deformation ability is as good as with general structural carbon steel, through the low power inspection, and forging macrostructure uniform and delicate, all flawless is pressed the GB14979-1994 standard rating, and the carbide unevenness reaches 2 grades.

Embodiment 2:

Use the present invention, each 50 of the ring body of forging external diameter 310mm, internal diameter 210mm, high 90mm and the cake bodies of external diameter 180mm, high 80mm are used for the making of trombone slide mould.It may further comprise the steps::

(1), add thermally homogenising: forging stock is warming up to 800 ℃ with stove, is incubated 2 hours, again with the heat-up rate of 95 ℃/h, is warming up to 1220 ℃, is incubated 3 hours, between soak forging stock is stood up 2 times;

(2), forging deformation: open and forge 1220 ℃ of temperature, 950 ℃ of final forging temperatures, upsetting pull is 5 times repeatedly, makes forging ratio＞8, when 950 ℃ of forging temperature, is heated to 1220 ℃ again, is incubated after 3 hours, forges again;

(3), forge postcooling: the cooling rate with 30 ℃/h is cooled to 100 ℃ with forging.

The finished product that obtains through aforesaid method, through check, its yield rate is 98%, and forging press the GB14979-1994 standard rating, and the carbide unevenness has improved 3 times the work-ing life of mould by forging preceding 7 grades of 1.5 grades of bringing up to after the forging.

Embodiment 3:

Use the present invention, 5 of the templates of forging 1500 * 800 * 100mm.It may further comprise the steps::

(1), add thermally homogenising: forging stock is warming up to 750 ℃ with stove, is incubated 1.5 hours, again with the heat-up rate of 95 ℃/h, is warming up to 1200 ℃, is incubated 2.5 hours, between soak forging stock is stood up 2 times;

(2), forging deformation: open and forge 1200 ℃ of temperature, 930 ℃ of final forging temperatures, upsetting pull is 5 times repeatedly, makes forging ratio＞8, when 930 ℃ of forging temperature, is heated to 1200 ℃ again, is incubated after 2.5 hours, forges again;

(3), forge postcooling: the cooling rate with 30 ℃/h is cooled to 100 ℃ with forging.

The finished product that obtains through aforesaid method, through check, its yield rate is 100%, and forging press the GB14979-1994 standard rating, and the carbide unevenness has improved 4 times the work-ing life of mould by forging preceding 8 grades of 2 grades of bringing up to after the forging.

Claims (1)

1. the forging method of a Cr12MoV cold work die steel module, it is characterized in that: it may further comprise the steps:

(1), add thermally homogenising: forging stock is warmed up to 700 ℃-800 ℃ with stove, is incubated 1-2 hour, again with the heat-up rate of 50-100 ℃/h, is warming up to 1190 ℃-1220 ℃, is incubated 2-3 hour, between soak base substrate is stood up, to reduce the male and female face temperature head;

(2), forging deformation: open and forge 1190 ℃-1220 ℃ of temperature, 900 ℃-950 ℃ of final forging temperatures, upsetting pull is 4-5 time repeatedly, make forging ratio＞8, when the forging temperature is lower than 900 ℃ of-950 ℃ of scopes, be heated 1190 ℃-1220 ℃ again, be incubated and forge again after 2-3 hour;

(3), forge postcooling: the cooling rate with 30 ℃/h is cooled to 100 ℃ with forging.