The manufacturing method of automobile stabilizer bar unimach and stabiliser bar
Technical field
The invention belongs to steel alloy and steel pipe manufacturing fields, and in particular to a kind of automobile stabilizer bar unimach and steady
Fixed pole manufacturing method.
Background technique
Automobile stabilizer bar be in order to prevent automobile turning when the torque arm that laterally topples, be typically secured to automobile chassis or so
The lower arm of suspension.With resource, the increasingly increase of the energy, environmental pressure, lightweight is realized under the premise of guaranteeing vehicle performance
Have become the trend of current automotive industry.Automobile stabilizer bar uses high-intensitive and high-ductility hollow component to reduce steel
Dosage is one of effective way of automobile lightweight.
In recent years for energy saving, simplified process, automobile and the higher components of mechanical performance requirement are developed in succession
The new materials such as non-hardened and tempered steel, air-cooled bainitic steels out, but using less in spring-like product.Such as Publication No. CN
102899589A " a kind of high intensity non quenched and tempered bainitic steel and preparation method " is that quick air-cooled obtaining portion is divided after crankshaft forging
The method that bainite structure replaces quenched steel crankshaft.Although having added a variety of noble elements such as Mo, V, Cr in steel, obtained because final
Tissue obdurability deficiency (the tensile strength R arrivedm>=1085MPa, yield strength Rp0.2>=795MPa), it is not able to satisfy stabiliser bar class
The mechanical property requirements of elastic component.The requirement of spring product is also not achieved in the mechanical property of most high tough air-cooled bainitic steels,
Some then containing there are many noble element or rare element (such as Mo, Ni, V) of high level, keeps material cost very high and is difficult to
Practical application.The patent " air-cooled bainite steel with high toughness and high quenching performance " of publication number CN 1078269A emphasizes high-hardenability,
Large-sized part natural cooling in air, i.e. cooling rate >=1 DEG C/min between 900 DEG C ~ 300 DEG C are asked, but is
Guarantee harden ability and the content for improving the elements such as Mn, Si of having to, to be also added the noble elements such as Mo, V, material cost compared with
It is high.In addition, the part air-cooled required time is very long, the Automotive Stabilizer Bar for requiring short cycle to produce in enormous quantities is made to be difficult to obtain
Practical application.Publication number Cn 105088081A " manufacturing process of stabiliser bar bainite and martensite spring steel and stabiliser bar ",
Cooling obtain of control is used to add part low-carbon martensite and a small amount of retained austenite with bainite after being heated to 900 DEG C ~ 1050 DEG C,
Then lonneal makes material mechanical performance reach Rm>=1350MPa, yield strength Rp0.2>=1050MPa, elongation after fracture A >=
10%, contraction percentage of area Z >=35%.However its intensity is still lower, it is difficult to meet the needs of automotive light weight technology.
Summary of the invention
The purpose of the present invention is in view of the above technical problems, by ingredient design and thermomechanical treatment process, form crystal grain
The fine uniform and tough automobile of height being made of bainite/lath martensite/retained austenite/lamellar martensite heterogeneous structure is steady
Fixed pole.
To achieve the object of the present invention, change of the automobile stabilizer bar of the present invention with unimach comprising following weight percent
It studies point: C 0.20% ~ 0.50%, Mn 0.50% ~ 3.0%, Cr 0.01% ~ 0.45%, Al 0.015% ~ 0.07%, Si 0.20% ~
1.35%, B 0.001% ~ 0.006%, V+Ti 0.01 ~ 1.20%, remaining is Fe and inevitable impurity.
Preferably, the chemical composition comprises the following components in percentage by weight of automobile stabilizer bar unimach of the present invention are as follows: C 0.35%
~ 0.40%, Mn 2.1% ~ 2.5%, Cr 0.18% ~ 0.27, Al 0.04% ~ 0.06%, Si 1.20 ~ 1.35%, B 0.004 ~
0.006%, V 0.04 ~ 0.05, Ti 0.03 ~ 0.04.
The manufacturing process of automobile unimach stabiliser bar of the present invention, comprising the following steps:
(1) raw material for constituting the chemical component of the unimach successively carry out converter or electric furnace smelting, the refining of LF furnace and
VD furnace vacuum outgas;
(2) the molten steel continuous casting and rolling of refining gained is at round steel billet, and removes surface folding and defect;
(3) roll piercing is carried out to round steel billet and determines tube reducing;
(4) annealing and pickling;
(5) 3 ~ 5 passage cold-drawns and 1 passage empty sinking are carried out, is made annealing treatment after cold-drawn each time;
(6) it is heat-treated.
Further, in step (3), roll piercing temperature is 1100 DEG C ~ 1250 DEG C, drafts 10 ~ 25%.
Further, in step (4), specific steps are made annealing treatment are as follows: first by steel pipe in 760 DEG C ~ 850 DEG C heat preservation 1h ~ 5h,
Afterwards in 650 DEG C ~ 780 DEG C heat preservation 1h ~ 5h;Pickling use concentration for 4% ~ 25% hydrochloric acid or sulfuric acid.
Further, in step (5), 3 passage cold-drawns are carried out, wherein the deflection and mill speed of cold-drawn are respectively 14%
~17%,2m/min;20%~21%,2.5m/min;24% ~ 25%, 3m/min, the deflection and mill speed of empty sinking be 22% ~ 23%,
3m/min.The temperature of cold-drawn after annealing processing each time is 700 DEG C ~ 780 DEG C, soaking time 1h ~ 5h.
Further, in step (6), specific steps are heat-treated are as follows: steel pipe is heated to Ac1 or more 20 DEG C ~ 100 first
DEG C, 5min ~ 30min is kept the temperature, subsequent air accelerates cooling or water cooling to 250 DEG C ~ 450 DEG C, keeps the temperature 30mim ~ 150min, last empty
Gas accelerates cooling or water cooling.
The design considerations of chemical composition and critical process of the invention is as follows:
C is the most frequently used also most effective intensified element in steel, is played a role by gap solution strengthening and Carbide Precipitation reinforcing.
Carbon content is designed in the present invention between 0.20% ~ 0.50%, by being quickly cooled to one between Ms point and Mf point after austenitizing
Determine temperature, obtains lath martensite and bainite and a small amount of retained austenite of appropriate level.In this temperature, promote carbon first
Element improves stabilization of austenite from being spread in oversaturated martensite and bainite to retained austenite.Finally it is quickly cooled to
Room temperature makes the lamellar martensite of retained austenite portions turn high-carbon to improve intensity, partially remains and subsequent
Cold working or military service deformation process in deformation occurs induced phase transition and improve plasticity and toughness.C content is too low can not to form enough numbers
The martensite and bainite of amount, intensity is insufficient, too high, reduces plasticity and welding performance.
The intensity and harden ability of matrix can be improved in the addition of Mn element in steel of the present invention, and by reducing the refinement of Ac3 temperature
Crystal grain after cooling, in addition, Mn also improves austenite content and stability as austenite former, so as to improve modeling
Toughness.But excessively high Mn content makes serious steel billet segregation, thermal stress and big, the weldability decline of structural stress etc., designs accordingly
Mn content is between 0.50% ~ 3.0%.
A small amount of Cr and B element ensure that the harden ability of steel, make steel that can also form sufficient amount of plate under the conditions of air-cooled
Martensite and bainite.However excessive Cr keeps steel firmly crisp, therefore by the control of Cr content between 0.01% ~ 0.45%.
Si can be strengthened by way of gap is dissolved, to improve tensile strength and yield strength simultaneously.Si can be shown
The formation for hindering carbide is write, the fine-scale of carbide is on the one hand realized, on the other hand guarantees that enough C elements diffuse to
In austenite.Crackle tendency when Si too high levels make Tube Drawing improves, and deteriorates welding performance, and easily lead to it is cold short, accordingly
The Si content of design is between Si 0.20% ~ 1.35%.
V and Ti element can form tiny carbide and be strengthened, and hinder grain coarsening, and steel is made to keep small grains ruler
Degree.
The stabiliser bar produced using automobile stabilizer bar unimach of the present invention and stabiliser bar manufacturing method, passes through low-carbon
Lath martensite, bainite and high-carbon lamellar martensite are strengthened, and are mentioned by the phase transformation effect of retained austenite
High-plasticity.Compared with prior art, the splendid matching of obdurability is realized, comprehensive mechanical property is much better than existing steel grade, fills
Divide the mechanical property requirements for meeting stabiliser bar class elastic component, stabiliser bar rolled steel dosage, automobile lightweight can be reduced.
Detailed description of the invention
Fig. 1 is the SEM scanning electricity of the automobile stabilizer bar unimach matrix of 1 manufacture according to embodiments of the present invention
Mirror figure.
Fig. 2 is engineering stress-strain curve of the automobile stabilizer bar unimach of 1 manufacture according to embodiments of the present invention
Figure.
Specific embodiment
Below according to specific embodiment, technical scheme is described further.Protection scope of the present invention is unlimited
In following embodiment, these embodiments are enumerated merely for exemplary purpose without limiting the invention in any way.
Embodiment 1
It successively carries out electric furnace smelting, the refining of LF furnace, the vacuum outgas of VD furnace and continuous casting and rolling and automobile stabilizer bar superhigh intensity is made
Steel round blank, chemical composition are C 0.39%, Mn 2.21%, Cr 0.25%, Al 0.06%, Si 1.33%, B 0.005%, V
0.04, Ti 0.04%.In 1200 DEG C of roll piercings, drafts 20% directly determines tube reducing after perforation.Hereafter it is made annealing treatment simultaneously
Pickling: first by steel pipe after 800 DEG C of heat preservation 1.5h in 720 DEG C of heat preservation 1h;Pickling use concentration for 10%% hydrochloric acid or sulfuric acid.It is right
Steel pipe carries out 3 passage cold-drawns, and pass deformation and mill speed are respectively 14%, 20%, 24%;2mm/min,2.5mm/min,
3mm/min, and made annealing treatment after cold rolling every time.Steel pipe is heated to 930 DEG C, keeps the temperature 12min, subsequent water cooling to 350
DEG C, keep the temperature 150min, rear water cooling to room temperature.Finally stabiliser bar assembly is made by existing conventional stabiliser bar assembly production method.
The stabiliser bar matrix of the present embodiment production is lath martensite, lamellar martensite and retained austenite, is averaged
Less than 10 μm (see figure 1)s of crystallite dimension.Water cooling makes austenite fraction mutually become lath martensite, portion to 320 DEG C after austenitizing
Code insurance is left retained austenite, and subsequent isothermal heat preservation expands oversaturated carbon in lath martensite into residual austenite body
It dissipates, last water cooling makes portion of residual austenite be changed into lamellar martensite, and part retains to room temperature, final residual austenite content
About 9.2%.The generation of high-carbon lamellar martensite is so that the intensity of material is further increased compared to single lath martensite, inversion
The elements such as austenite richness C, Mn, thermodynamic stability is good, martensitic traoformation does not occur in cooling procedure, but in deformation process
Martensitic traoformation occurs, the generation in advance of dissipation energy, the generation and constriction that avoid micropore is dropped simultaneously so as to improve plasticity and toughness
Low yield strength ratio.The stress-strain diagram of the present embodiment unimach is as shown in Fig. 2, its mechanical property are as follows: tensile strength
1756MPa, yield strength 1447MPa, elongation percentage 13.2%.
Embodiment 2
For other steps with embodiment 1, steel pipe chemical composition is C 0.48%, Mn 1.34%, Cr 0.40%, Al 0.037%,
Si 0.76%, B 0.005%, V 0.07, Ti 0.02%.Steel pipe is heated to 920 DEG C after cold-drawn, keeps the temperature 15min, subsequent water
It is cooled to 250 DEG C, keeps the temperature 60min, last water cooling to room temperature.Its residual austenite content about 4.5%, tensile strength 1774MPa are bent
Take intensity 1468MPa, elongation percentage 10.4%.
Embodiment 3
For other steps with embodiment 1, steel pipe chemical composition is C 0.21%, Mn 0.50%, Cr 0.28%, Al 0.042%,
Si 1.35%, B 0.004%, V 0.08.Steel pipe is heated to 950 DEG C after cold-drawn, keeps the temperature 5min, subsequent water cooling to 380 DEG C,
Keep the temperature 120min, last water cooling to room temperature.Its residual austenite content about 9.1%, tensile strength 1658MPa, yield strength
1453MPa, elongation percentage 14.2%.
Embodiment 4
For other steps with embodiment 1, steel pipe chemical composition is C 0.35%, Mn 2.96%, Cr 0.37%, Al 0.045%,
Si 1.20%, B 0.004%, V 0.02, Ti 0.03.Steel pipe is heated to 920 DEG C after cold-drawn, keeps the temperature 20min, subsequent water cooling
To 320 DEG C, 30min, last water cooling to room temperature are kept the temperature.Its residual austenite content about 7.5%, tensile strength 1742MPa, surrender
Intensity 1453MPa, elongation percentage 12.4%.
Embodiment 5
For other steps with embodiment 1, steel pipe chemical composition is C 0.28%, Mn 1.45%, Cr 0.02%, Al 0.07%, Si
0.89%, B 0.005%, V 0.07, Ti 0.01.Steel pipe is heated to 900 DEG C after cold-drawn, keeps the temperature 20min, subsequent water cooling is extremely
280 DEG C, keep the temperature 45min, last water cooling to room temperature.Its residual austenite content about 6.8%, tensile strength 1635MPa, surrender are strong
Spend 1428MPa, elongation percentage 13.3%.
Comparative example 1
For other steps with embodiment 1, steel pipe chemical composition is C 0.15%, Mn 0.75%, Cr 0.04%, Al 0.052%,
Si 1.21%, B 0.006%, V 0.06, Ti 0.03.Steel pipe is heated to 920 DEG C after cold-drawn, keeps the temperature 10min, subsequent water cooling
To 300 DEG C, 40min, last water cooling to room temperature are kept the temperature.Its carbon content is less, and the lath martensite intensity of formation is insufficient, does not have simultaneously
There are enough carbon stable austenites, residual austenite content is few, and is difficult to form lamellar martensite, and tensile strength 1451MPa is bent
Take intensity 1245MPa, elongation percentage 10.2%.
Comparative example 2
For other steps with embodiment 1, steel pipe chemical composition is C 0.43%, Mn 0.82%, Cr 0.03%, Al 0.031%,
Si 1.26%, B 0.004%, V 0.08.Steel pipe is heated to 1000 DEG C after cold-drawn, keeps the temperature 10min, subsequent water cooling to 320
DEG C, keep the temperature 45min, last water cooling to room temperature.Since austenitizing temperature is excessively high, crystal grain is roughened, and after austenitizing
Quenching structure in start to generate lamellar martensite, the lamellar martensite generated in size and retained austenite mutually becomes apparent slightly
Change, thus damages plasticity, tensile strength 1724MPa, yield strength 1467MPa, elongation percentage 6.7%.
Comparative example 3
For other steps with embodiment 1, steel pipe chemical composition is C 0.30%, Mn 2.11%, Cr 0.36%, Al 0.04%, Si
1.02%, B 0.004%, V 0.06%.Steel pipe is heated to 920 DEG C after cold-drawn, keeps the temperature 12min, subsequent water cooling is protected to 200 DEG C
Warm 50min, last water cooling to room temperature.Its matrix is lath martensite and a small amount of retained austenite, and austenite content is about
1.3%, tensile strength 1526MPa, yield strength 1468MPa, elongation percentage 8.9%.
Comparative example 4
For other steps with embodiment 1, steel pipe chemical composition is C 0.24%, Mn 1.73%, Cr 0.35%, Al 0.06%, Si
0.75%, B 0.002%, V 0.04, Ti 0.04.Steel pipe is heated to 920 DEG C after cold-drawn, keeps the temperature 15min, subsequent water cooling is extremely
450 DEG C, keep the temperature 30min, last water cooling to room temperature.Its matrix is single bainite, tensile strength 968MPa, yield strength
744MPa, elongation percentage 16.8%.
The stabiliser bar that automobile stabilizer bar unimach of the present invention and stabiliser bar manufacturing method provide, by lath horse
The retained austenite of high-intensitive lamellar martensite and high tenacity is further introduced on family name's body/bainite matrix to improve mechanical property
Can, yield strength Rp0.2>=1400Mpa, tensile strength Rm>=1600MPa, elongation after fracture A >=10%, the comprehensive mechanics of obdurability
Performance is much better than existing steel grade, sufficiently meets the mechanical property requirements of stabiliser bar class elastic component, can reduce stabiliser bar rolled steel dosage,
Automobile lightweight.
By the mechanical property induction and contrast such as table 1 of steel obtained by embodiment 1-5 and comparative example 1-4, it is possible to find side of the present invention
Stabiliser bar steel comprehensive mechanical property obtained by case is outstanding.
1 embodiment of table is compared with stabiliser bar obtained by comparative example with steel mechanical property
| Embodiment |
Tensile strength (MPa) |
Yield strength (Mpa) |
Elongation percentage (%) |
| Embodiment 1 |
1756 |
1447 |
13.2 |
| Embodiment 2 |
1774 |
1468 |
10.4 |
| Embodiment 3 |
1658 |
1453 |
14.2 |
| Embodiment 4 |
1742 |
1453 |
12.4 |
| Embodiment 5 |
1635 |
1428 |
13.3 |
| Comparative example 1 |
1451 |
1245 |
10.2 |
| Comparative example 2 |
1724 |
1467 |
6.7 |
| Comparative example 3 |
1526 |
1468 |
8.9 |
| Comparative example 4 |
968 |
744 |
16.8 |