CN106636578A - Softening method of auto parts cold extruding billet - Google Patents
Softening method of auto parts cold extruding billet Download PDFInfo
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- CN106636578A CN106636578A CN201611052165.9A CN201611052165A CN106636578A CN 106636578 A CN106636578 A CN 106636578A CN 201611052165 A CN201611052165 A CN 201611052165A CN 106636578 A CN106636578 A CN 106636578A
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- blank
- billet
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/26—Methods of annealing
- C21D1/28—Normalising
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
- C23C22/05—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions
- C23C22/06—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6
- C23C22/07—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6 containing phosphates
Abstract
The invention relates to the technical field of heat treatment, and concretely relates to a softening method of an auto parts cold extruding billet. The softening method of the auto parts cold extruding billet adopts an isothermal normalizing process for softening the cold extruding billet at a hot rolling state, and comprises the concrete steps of firstly, blanking, and cutting hot-rolled round steel into the billet with the required specification; secondly, feeding, and placing the billet on a material rack of a production line; then carrying out isothermal normalizing treatment on the billet, i.e. entirely softening the billet so as to enable the billet to be sufficient in structure transformation and uniform in hardness; shot blasting the surface of the billet through a steel ball, and removing oxide skin; carrying out phosphorus saponification treatment, i.e. softening the surface of the billet; and finally, extrusion forming the billet, and carrying out flow detection on a cold extruding product. The softening method of the auto parts cold extruding billet provided by the invention solves the problems of low final heat-treatment core hardness, long production cycle and low efficiency, and is beneficial for cost reduction and industrial production in large volumes.
Description
Technical field
The present invention relates to a kind of method of technical field of heat treatment, specifically a kind of automobile component part cold extrusion blank it is soft
Change method.
Background technology
With the high speed development of auto industry, cold-extrusion technology both domestic and external has large development, and this is for cold-extruded pressed compact
The performance of material proposes new requirement.It is required that blank plasticity is good, it is readily flowed in the case where low unit overstocks, do not ftracture during extruding,
Core hardness of finished heat treatment etc..It is generally believed that spherodized structure is the most important condition for obtaining low unit compression, because this
The work hardening rate of tissue is low, thus is improved the cold overstocked performance of steel, and domestic and international cold extrusion blank is mostly to have carried out
Full annealing or spheroidizing.
Cold extrusion blank softening is to ensure that being smoothed out for cold-extrusion technology, advantageously reduces part after finished heat treatment
Deformation, it is ensured that finished heat treatment obtains rational hardness and metallographic structure.Annealing process is generally used to cold-extruded
Pressed compact material carries out sofening treatment, to reach the purpose for being smoothed out cold-extrusion technology.Generally technique be blank Ac1 temperature with
Upper 30～50 DEG C of scope inside holdings 0.5～1.5 hour, with the cooling velocity of 15～25 DEG C/h Ar1 ± 20 DEG C are cooled to, insulation
2.5～3.5 hours；30～50 DEG C of scope inside holdings are again heated to more than Ac1 temperature 0.5～1.5 hour, with 15～25 DEG C/h's
Cooling velocity is cooled to Ar1 ± 20 DEG C, and insulation is cooled to room temperature and comes out of the stove after 2.5～3.5 hours with stove.This technique can reach cold-extruded
The technological requirement of compression moulding deformation behavior, but process cycle is long, low production efficiency, and particularly the Mn-Cr systems that automobile industry is commonly used are oozed
Carbon steel centre hardness after the tempering of final carburizing and quenching is low, is not suitable for using this technique.
The content of the invention
The present invention is for the not enough and defect in ground in prior art, there is provided a kind of softening side of automobile component part cold extrusion blank
Method so as to which it is low to solve finished heat treatment centre hardness, long the production cycle, the low problem of efficiency, reduces cost, beneficial to large batch of
Industrialized production.
The present invention is achieved by the following technical solutions, and the present invention adopts cold-extruded of the isothermal normalizing technique to hot bundle state
Pressed compact material is softened, specially：First blanking, by hot rolled circular steel the blank of required specification is cut into；Secondly feed, blank is put
Put to the bin of production line；Then isothermal normalizing process is carried out to blank, i.e., overall softening is carried out to blank makes structural transformation
Fully, hardness is uniform；Again shotblasting process is carried out by steel ball, dispel oxide skin；Then phosphorus saponification process is carried out, i.e., to base
Material carries out surface sofening treatment；Finally by blank extrusion molding, and cold-extruded die pressing product is detected a flaw using supersonic detector.
Described blanking, refers to：According to the needs of cold-extruded die pressing product, the round steel of hot-rolled state is cut into into the length of needs
Degree, and consider the fire consumption problem of later process, typically take 1～2% fire consumption.
Described charging, refers to：The disposing way of feed way and blank is determined according to the concrete shape of blank, it is substantially former
Then one it is advantageous for the flexural deformation problem that heat transfer two is consideration blank (particularly elongated blank).Suggestion elongate articles are vertical
Put.
Described isothermal normalizing is processed and is divided into：Heating and thermal insulation, cooling, isothermal insulation three phases, it is specific as follows：
(1) heating and thermal insulation
To more than austenitizing temperature, insulation makes blank complete the process of austenitizing to blank heating.The process includes rising
Warm process, austenitic formation (including nucleation and grow up), Residual Carbides dissolving, homogeneity of austenite component Four processes.
A, temperature-rise period
Because in the range of certain firing rate, critical point increases with firing rate and raises；Shape during quick laser heating
Into austenite into distributing homogeneity increase.So, heat temperature raising speed is difficult excessive, it is proposed that firing rate be 1.2～
1.8min/mm。
B, austenitic formation process
After blank heating is to austenitizing temperature, austenite nucleus just goes out to be formed in ferrite and Cementite face,
And constantly by the dot matrix reconstruct between ferrite and austenite, the diffusion of the dissolving of cementite and carbon in austenite is realized
Austenite crystal is constantly grown up.
C, Residual Carbides dissolving
Due to being laser heating (or the degree of superheat is bigger), the carbide quantity remained in blank the more, only continues to protect
Temperature, Residual Carbides could gradually dissolve.This process is required, must be considered during technique initialization.
D, homogeneity of austenite component
When perlitic transformation is austenite, in the case where residual cementite is just fully immersed into austenite, carbon is in Ovshinsky
Internal is distributed uneven, and blank can be affected to soften the uniformity of hardness, the uniformity of tissue, the plastic deformation energy of blank
Power declines, and is unfavorable for cold-extrusion shaping.Therefore, softening process must take into the process of homogeneity of austenite component, typically in Austria
Family name's body temperature 0.5～1.5 hour.
For above-mentioned b, c, d, the heating and thermal insulation time is enough, i.e., temperature retention time make enough material complete austenitizing and
Homogenized.Depending on the heating and thermal insulation time will be according to different material behaviors, the conventional Mn-Cr systems mild steel of automobile industry,
Heating-up temperature is 930 ± 25 DEG C, and the heating and thermal insulation time is generally 2～3 hours.
(2) cool down
With less than critical cooling rate (different material critical cooling velocity is different, according to material composition and performance depending on,
This data can be looked into from steel handbook and take or obtained by testing) cooling, make blank be cooled to pearlite from austenitizing temperature
Transition temperature is interval, and along with structural transformation (austenite --- pearlite), the hardness of blank is substantially in this process shape
Into.Therefore, to the blank of different chemical composition, select the suitable type of cooling it is critical that, speed be difficult it is excessive, one
As be not more than 40 DEG C/min, it is interval more on the upper side that cooling finishing temperature is typically cooled to perlitic transformation problem.
(3) isothermal insulating process
Blank only has small part structural transformation in cooling procedure, and most tissues transformation is mainly completed in process,
That is austenite --- pearlite.Structural transformation now is carried out in certain temperature range, the interlayer of such pearlite
Away from equal, grain size is consistent, and structural constituent is uniform, and mechanical performance is uniform, beneficial to plastic deformation.Isothermal temperature, time determine
Foundation be itself being determined for blank, the conventional Mn-Cr systems mild steel of automobile industry, isothermal temperature is 625 ± 35 DEG C, etc.
The warm time is generally 1.5～2 hours.Total principle is to make structural transformation fully, and hardness is uniform.
Described ball blast, refers to：After isothermal normalizing, physics is carried out by the steel ball of Φ 1.0mm and dispels oxide skin process, choosing
With the Shot Blasting of little steel sand, there are two benefits：One is smoothly to dispel oxide skin, and two is to make blank surface produce compression,
Make blank surface dense structure a little.
Described phospholeum, refers to：The softening process of blank, what is used is also special production line, with isothermal normalizing not
It is the overall softening carried out to blank that same is isothermal normalizing, and phospholeum is the surface sofening treatment carried out to blank.In base
Material surface formed one layer of special lubrication supporting course (bonderite), to reduce Cold Extrusion Process between blank and mould
Coefficient of friction, that is, reduce the Forming Resistance (frictional force) between blank and mould, the mold use life-span is improved, beneficial to blank
Shaping, it is to avoid pull product or die surface and avoid making product surface form serious fish scale-shaped crackle.
Described extrusion molding, refers to：The process being molded in a mold using press blank.
Described flaw detection, refers to：The process of nondestructive testing is carried out to cold-extruded die pressing product, this process mainly inspection product is
It is no to have inherent quality defect, such as internal micro-flaw.
The principle of the softening process of cold extrusion blank：One is the needs for meeting cold-extrusion technology, including the need of later process
Ask, two is inexpensive.Compared with traditional annealing (spheroidizing) technique, the present invention pricks shape using isothermal normalizing technique to heat
The cold extrusion blank of state is softened, and breaches traditional annealing process, is fully able to reach cold extrusion to blank plasticity
Deformation requirements, are plastically deformed, without cracking, and solve the low difficult problem of part core hardness after the quenching of low-carbon alloy carburizing steel
(some cold extrusion parts are softened using annealing process, then its core hardness does not reach technical requirements after carburizing and quenching).
Specific embodiment
Following examples are provided with reference to present disclosure to be explained：
Embodiment 1
Isothermal normalizing technique is just employed to it to the cold-stamped transmission output shaft of 20MnCr5 materials using the present invention
The sofening treatment of blank is carried out, detailed process and result are as follows：
Sawing machine blanking is utilized by technological requirement to the 20MnCr5 round steel of Φ 38, vertical display is to isothermal normalizing production line
On bin, 930 DEG C are first heated to using isothermal normalizing, are incubated 2.5 hours, control is air cooled to 620 DEG C and is incubated 1.5 hours, comes out of the stove
Air cooling.The blank hardness for obtaining is 160～165HB, and metallographic structure is uniform pearlite；Carry out surface on shot-blasting machine to dispel
Oxide skin process；Carry out phosphorus saponification process using phospholeum metaplasia producing line, Phosphating Solution temperature control in the range of 95 ± 5 DEG C, phosphatization
Time is 20 minutes or so, and the saponification process of 8 minutes is carried out after washing, finally carries out the drying and processing of blank；In four column pressures
Carry out being carried out after cold-extrusion shaping process total nondestructive inspection on machine and do not find micro-flaw, it is all qualified.
It is that 481～492Hv30 of centre hardness has reached technical requirements in the tracking result to final carburizing and quenching；And make
Spheroidizing softening process is used, centre hardness is 369～374Hv30 after its final carburizing and quenching, less than technical requirements.And wait
The production cycle of warm normalizing process is about 4～6 hours, 10～20 hours production cycles with spheroidizing, compares production effect
Rate improves 2.5～5 times, is conducive to industrialized production.
Additionally, also cold extrusion sofening treatment has been carried out to materials such as 16MnCr5,20MnCr5,20CrMnTi, 20CrMoH,
Millions of of product is criticized over several years, has obtained good effect.
Embodiment 2
Isothermal normalizing technique is just employed to it to the cold-stamped transmission input shaft of 16MnCr5 materials using the present invention
The sofening treatment of blank is carried out, detailed process and result are as follows：
Sawing machine blanking is utilized by technological requirement to the 16MnCr5 round steel of Φ 38, vertical display is to isothermal normalizing production line
On bin, 950 DEG C are first heated to using isothermal normalizing, are incubated 1.5 hours, control is air cooled to 590 DEG C and is incubated 2 hours, sky of coming out of the stove
It is cold.The blank hardness for obtaining is 165～170HB, and metallographic structure is uniform pearlite；Surface is carried out on shot-blasting machine and dispels oxygen
Change skin to process；Phosphorus saponification process is carried out using phospholeum metaplasia producing line, in the range of 90 DEG C, phosphating time is Phosphating Solution temperature control
20 minutes or so, the saponification process of 5 minutes is carried out after washing, finally carry out the drying and processing of blank；It is enterprising in four column press
Total nondestructive inspection is carried out after the process of row cold-extrusion shaping and does not find micro-flaw, it is all qualified；Final carburizing and quenching hardness
(including centre hardness) has reached technical requirements.
Embodiment 3
Isothermal normalizing technique is just employed to it to the cold-stamped transmission output shaft of 20CrMoH materials using the present invention
The sofening treatment of blank is carried out, detailed process and result are as follows：
Sawing machine blanking is utilized by technological requirement to the 20CrMoH round steel of Φ 43, vertical display is to isothermal normalizing production line
On bin, 905 DEG C are first heated to using isothermal normalizing, are incubated 2 hours, control is air cooled to 660 DEG C and is incubated 2 hours, air cooling of coming out of the stove.
The blank hardness for obtaining is 160～165HB, and metallographic structure is uniform pearlite；Surface is carried out on shot-blasting machine and dispels oxidation
Skin process；Carry out phosphorus saponification process using phospholeum metaplasia producing line, Phosphating Solution temperature control in the range of 95 ± 5 DEG C, phosphating time
For 20 minutes or so, the saponification process of 10 minutes is carried out after washing, finally carry out the drying and processing of blank；On four column press
Carry out being carried out after cold-extrusion shaping process total nondestructive inspection and do not find micro-flaw, it is all qualified；Final carburizing and quenching is hard
Degree has reached technical requirements (including centre hardness).
Claims (9)
1. a kind of softening method of automobile component part cold extrusion blank, it is characterised in that shape is pricked to heat using isothermal normalizing technique
The cold extrusion blank of state is softened, first blanking, and hot rolled circular steel is cut into into the blank of required specification；Secondly feed, by blank
It is placed on the bin of production line；Then isothermal normalizing process is carried out to blank, i.e., overall softening is carried out to blank turns tissue
Change is abundant, hardness is uniform；Again blank surface Shot Blasting is carried out by steel ball, dispel oxide skin；Then phosphorus saponification process is carried out,
Surface sofening treatment is carried out to blank；Finally by blank extrusion molding, and cold-extruded die pressing product is detected a flaw.
2. the softening method of a kind of automobile component part cold extrusion blank according to claim 1, it is characterised in that described
Isothermal normalizing process is divided into：Heating and thermal insulation, cooling, isothermal insulation three phases, it is specific as follows：
(1) heating and thermal insulation：To more than austenitizing temperature, insulation makes blank complete the process of austenitizing, the mistake to blank heating
Journey includes temperature-rise period, austenitic formation, Residual Carbides dissolving, homogeneity of austenite component；
A, temperature-rise period：Firing rate is 1.2～1.8min/mm；
B, austenitic formation process：To austenitizing temperature, austenite nucleus is just in ferrite and carburizing body phase for blank heating
Interface goes out to be formed, and is reconstructed by the dot matrix between ferrite and austenite, the expansion of the dissolving of cementite and carbon in austenite
Dissipate and realize growing up for austenite crystal；
C, Residual Carbides dissolving：Laser heating or the degree of superheat cause more greatly the carbide quantity remained in blank the more, lead to
Continuation of insurance temperature of adopting gradually dissolves Residual Carbides；
D, homogeneity of austenite component：0.5～1.5 hour is incubated in austenitizing temperature；
(2) cool down：To cool down less than critical cooling rate, cooling velocity is less than or equal to 40 DEG C/min；
(3) isothermal insulating process：For Mn-Cr systems mild steel, isothermal temperature is 625 ± 35 DEG C, and isothermal time is 1.5～2 little
When.
3. the softening method of a kind of automobile component part cold extrusion blank according to claim 2, it is characterised in that described
Heating and thermal insulation, for Mn-Cr systems mild steel, heating-up temperature is 930 ± 25 DEG C, and the heating and thermal insulation time is 2～3 hours.
4. the softening method of a kind of automobile component part cold extrusion blank according to claim 1, it is characterised in that described
Blanking, refers to：The round steel of hot-rolled state is cut into into the length of needs, later process takes 1～2% fire consumption.
5. the softening method of a kind of automobile component part cold extrusion blank according to claim 1, it is characterised in that described
Ball blast, refers to：After isothermal normalizing, physics is carried out by the steel ball of Φ 1.0mm and dispels oxide skin process.
6. the softening method of a kind of automobile component part cold extrusion blank according to claim 1, it is characterised in that described
Phospholeum, refers to：The softening process of blank, it is bonderite to form one layer of lubrication supporting course in blank surface, to reduce
Coefficient of friction in Cold Extrusion Process between blank and mould.
7. the softening method of a kind of automobile component part cold extrusion blank according to claim 1, it is characterised in that described
Phospholeum, in the range of 95 ± 5 DEG C, phosphating time is 20 minutes to Phosphating Solution temperature control, and the soap of 5～10 minutes is carried out after washing
Change is processed, and finally carries out the drying and processing of blank.
8. the softening method of a kind of automobile component part cold extrusion blank according to claim 1, it is characterised in that described
Extrusion molding, refers to：The process being molded in a mold using press blank.
9. the softening method of a kind of automobile component part cold extrusion blank according to claim 1, it is characterised in that described
Flaw detection, refers to：The process of nondestructive testing is carried out to cold-extruded die pressing product using supersonic detector, whether inspection product has inherent matter
Amount defect.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201611052165.9A CN106636578A (en) | 2016-11-25 | 2016-11-25 | Softening method of auto parts cold extruding billet |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201611052165.9A CN106636578A (en) | 2016-11-25 | 2016-11-25 | Softening method of auto parts cold extruding billet |
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| CN106636578A true CN106636578A (en) | 2017-05-10 |
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| CN201611052165.9A Withdrawn CN106636578A (en) | 2016-11-25 | 2016-11-25 | Softening method of auto parts cold extruding billet |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112853048A (en) * | 2019-11-27 | 2021-05-28 | 南京工程学院 | Method suitable for preliminary heat treatment of cold extrusion high-temperature carburized part |
| CN114011896A (en) * | 2021-10-11 | 2022-02-08 | 南京金城三国机械电子有限公司 | Softening method of cold extrusion blank |
-
2016
- 2016-11-25 CN CN201611052165.9A patent/CN106636578A/en not_active Withdrawn
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112853048A (en) * | 2019-11-27 | 2021-05-28 | 南京工程学院 | Method suitable for preliminary heat treatment of cold extrusion high-temperature carburized part |
| CN114011896A (en) * | 2021-10-11 | 2022-02-08 | 南京金城三国机械电子有限公司 | Softening method of cold extrusion blank |
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Application publication date: 20170510 |
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