CN109680211A - A kind of manufacturing method of vehicle structure steel and its manufacturing method and automobile structure - Google Patents
A kind of manufacturing method of vehicle structure steel and its manufacturing method and automobile structure Download PDFInfo
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- CN109680211A CN109680211A CN201811625772.9A CN201811625772A CN109680211A CN 109680211 A CN109680211 A CN 109680211A CN 201811625772 A CN201811625772 A CN 201811625772A CN 109680211 A CN109680211 A CN 109680211A
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
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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
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
- C21D8/0226—Hot rolling
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- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/005—Ferrous alloys, e.g. steel alloys containing rare earths, i.e. Sc, Y, Lanthanides
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- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
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- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
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- C22C38/08—Ferrous alloys, e.g. steel alloys containing nickel
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- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/12—Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium
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- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/22—Ferrous alloys, e.g. steel alloys containing chromium with molybdenum or tungsten
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- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/24—Ferrous alloys, e.g. steel alloys containing chromium with vanadium
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- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/26—Ferrous alloys, e.g. steel alloys containing chromium with niobium or tantalum
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- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
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- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/32—Ferrous alloys, e.g. steel alloys containing chromium with boron
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- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/38—Ferrous alloys, e.g. steel alloys containing chromium with more than 1.5% by weight of manganese
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- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/44—Ferrous alloys, e.g. steel alloys containing chromium with nickel with molybdenum or tungsten
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- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/46—Ferrous alloys, e.g. steel alloys containing chromium with nickel with vanadium
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/48—Ferrous alloys, e.g. steel alloys containing chromium with nickel with niobium or tantalum
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/54—Ferrous alloys, e.g. steel alloys containing chromium with nickel with boron
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/58—Ferrous alloys, e.g. steel alloys containing chromium with nickel with more than 1.5% by weight of manganese
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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
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/002—Bainite
Abstract
The invention discloses a kind of vehicle structure steel and its manufacturing methods of manufacturing method and automobile structure.Wherein, vehicle structure steel, in terms of quality %, it include: C:0.07%-0.15%, Si:0.1%-0.2%, Mn:1.0%-2.0%, P :≤0.015%, S :≤0.004%, Al :≤0.04%, N:0.0040%-0.0070%, Re:0.1%-0.4%, V:0.10%-0.20%, Nb:0.02%-0.06%, remaining is Fe and inevitable impurity.The present invention improves fatigue behaviour by reducing the difference of hardness of weld seam and its heat affected area and base material, improving surface of steel plate hardness, reduce the Large Inclusions in steel and reduce this four aspects of residual stress after molding.
Description
Technical field
The present invention relates to steelmaking technical field more particularly to a kind of vehicle structure steel and its manufacturing method and vehicle structures
The manufacturing method of part.
Background technique
Torsion beam of automobile belongs to semi-independent suspension, connects left and right trailing arm by crossbeam.When automobile occurs in the process of moving
When inclination, crossbeam twists deformation therewith, to provide torsion stiffness to improve the control stability of automobile.Further, since
Torsion beam is repeatedly subjected to shock loading and torsional load etc. in the process of moving, thus it has high fatigue properties and especially weighs
It wants.
Therefore, it is necessary to a kind of methods to guarantee that torsion beam has high fatigue properties.
Summary of the invention
The present invention is realized by providing the manufacturing method of a kind of vehicle structure steel and its manufacturing method and automobile structure
Improve the technical effect of fatigue properties.
The present invention provides a kind of vehicle structure steel, in terms of quality %, comprising: C:0.07%-0.15%, Si:
0.1%-0.2%, Mn:1.0%-2.0%, P :≤0.015%, S :≤0.004%, Al :≤0.04%, N:0.0040%-
0.0070%, Re:0.1%-0.4%, V:0.10%-0.20%, Nb:0.02%-0.06%, remaining is for Fe and inevitably
Impurity.
Further, in terms of quality %, also contain Ni:0.1%-0.4%, Cr:0.25%-0.45%, Mo:0.1%-
0.4%, B: any one in≤0.0008% or two kinds.
The present invention also provides a kind of manufacturing methods of vehicle structure steel, comprising:
Slab is smelted and is cast as according to the component content of such as above-mentioned vehicle structure steel；
The slab is heated；
Slab after heating is rolled；
Slab after rolling is cooled down, vehicle structure steel is obtained.
It is further, described that the slab is heated, comprising:
Two-part heating is carried out to the slab, soaking temperature is 1200 DEG C -1280 DEG C, and the total time inside furnace of steel billet is
200min-260min。
Further, the slab after described pair of heating rolls, comprising:
Roughing and finish rolling are successively carried out to the slab after heating.
Further, during the slab after described pair of heating successively carries out roughing and finish rolling, the roughing is adopted
With 6 passages, per pass equal de-scaling；First passage dependent variable control 0.2 hereinafter, remaining passage dependent variable control 0.45 with
Under；Roughing outlet temperature is controlled at 1150 DEG C -1100 DEG C；The finish rolling use 7 passages, per pass dependent variable control 0.2 with
Under, finish rolling start rolling temperature is 950 DEG C -1000 DEG C, and finish rolling finishing temperature is 850 DEG C -950 DEG C, and hot rolling plate thickness is not more than 6mm.
Further, during the slab after described pair of rolling cools down, cooling velocity is 30 DEG C/s-100
DEG C/s, coiling temperature is 550 DEG C -650 DEG C.
Further, it is described obtain vehicle structure steel after, further includes:
Pickling is carried out with steel to the vehicle structure.
The present invention also provides a kind of manufacturing methods of automobile structure, comprising:
2-5 times by the vehicle structure steel manufactured by such as above-mentioned manufacturing method using radius of curvature R as plate thickness
Bending forming；
Under conditions of tempering parameter is 12000-17000, the vehicle structure after bending forming is heat-treated with steel.
One or more technical solution provided in the present invention, has at least the following technical effects or advantages:
It selects C content range for 0.07%-0.15%, and adds a certain amount of solution strengthening element, thus guaranteeing to weld
While stitching intensity, also ensure that plastic property of weld bead not less than base material, thus reduces the hard of weld seam and its heat affected area and base material
It is poor to spend.In addition, being added to alloying element V in ingredient design, Low Temperature Heat Treatment is used after forming, the carbonitride containing V is in part
Surface is largely precipitated, hereby it is ensured that surface hardness.Meanwhile also added Re element, size is tiny, the spherical shape being evenly distributed
Rare-earth sulfide can replace completely banded MnS to be mingled with, and in thermal processing distortion, spherical rare-earth sulfide is still able to maintain
Tiny spherical shape or spindle, and it is more uniform be distributed in steel, thus eliminate be originally present along steel rolling
The ribbon MnS of directional spreding, and then improve the fatigue behaviour of steel.Ti element is not added, avoids the life of TiN type impurity
At, thus reduce the Large Inclusions in steel.In addition, also used in ingredient it is more improve harden ability element, as C, Mn,
Cr and Mo etc., in process air cooler after welding, weld dimensions tissue is close with base material based on bainite, therefore
Its mechanical property is also close with base material, thus improves fatigue behaviour.In addition, additionally using higher C and Mn in ingredient design
Content, and it is added to a certain amount of Cr element and Mo element.In addition, a certain amount of Ni or B of addition also may be selected, it is strong to be dissolved
Change；It also added a certain amount of Nb element in ingredient design, thus refined crystalline strengthening and inhibition coarse grains on surface.In addition, ingredient designs
In also added a certain amount of V and N, at steel plate thickness surface, after deformation strain hardening and heat treatment after organization softening the most
The Carbonitride Precipitation reinforcing in serious place, V is the most obvious, thus it is hard higher than center portion to maintain base material deformation rear surface hardness
The performance characteristics of degree.Meanwhile V and N can be precipitated under the conditions of lower temperature, it is thus possible to reduce heat treatment cost.Target is aobvious
Micro-assembly robot control is granular bainite, has taken into account the intensity and plasticity of steel, it is thus possible to further decrease and be brought by residual stress
Heat treatment cost.
In conclusion the present invention is hard by the difference of hardness of reduction weld seam and its heat affected area and base material, raising surface of steel plate
Degree reduces the Large Inclusions in steel and improves fatigue behaviour in terms of reducing residual stress this four after molding.
Detailed description of the invention
Fig. 1 is the flow chart of the manufacturing method of the vehicle structure steel of excelling in fatigue property provided in an embodiment of the present invention；
Fig. 2 is the flow chart of the manufacturing method of the automobile structure of excelling in fatigue property provided in an embodiment of the present invention；
Fig. 3 is the schematic shapes of structural member in the embodiment of the present invention；
Fig. 4 is firmness change schematic diagram in the embodiment of the present invention；
Fig. 5 is three-point bending punching press schematic diagram in the embodiment of the present invention；
Fig. 6 is fatigue experiment schematic diagram in the embodiment of the present invention；
Fig. 7 is that the microhardness of embodiment 3 (a) steel surveys variation diagram；
Fig. 8 is that the microhardness of embodiment 3 (b) steel surveys variation diagram.
Specific embodiment
The embodiment of the present invention is by providing the manufacturer of a kind of vehicle structure steel and its manufacturing method and automobile structure
Method realizes the technical effect for improving fatigue properties.
Technical solution in the embodiment of the present invention is to solve the above problems, general thought is as follows:
It selects C content range for 0.07%-0.15%, and adds a certain amount of solution strengthening element, thus guaranteeing to weld
While stitching intensity, also ensure that plastic property of weld bead not less than base material, thus reduces the hard of weld seam and its heat affected area and base material
It is poor to spend.In addition, being added to alloying element V in ingredient design, Low Temperature Heat Treatment is used after forming, the carbonitride containing V is in part
Surface is largely precipitated, hereby it is ensured that surface hardness.Meanwhile also added Re element, size is tiny, the spherical shape being evenly distributed
Rare-earth sulfide can replace completely banded MnS to be mingled with, and in thermal processing distortion, spherical rare-earth sulfide is still able to maintain
Tiny spherical shape or spindle, and it is more uniform be distributed in steel, thus eliminate be originally present along steel rolling
The ribbon MnS of directional spreding, and then improve the fatigue behaviour of steel.Ti element is not added, avoids the life of TiN type impurity
At, thus reduce the Large Inclusions in steel.In addition, also used in ingredient it is more improve harden ability element, as C, Mn,
Cr and Mo etc., in process air cooler after welding, weld dimensions tissue is close with base material based on bainite, therefore
Its mechanical property is also close with base material, thus improves fatigue behaviour.In addition, additionally using higher C and Mn in ingredient design
Content, and it is added to a certain amount of Cr element and Mo element.In addition, a certain amount of Ni or B of addition also may be selected, it is strong to be dissolved
Change；It also added a certain amount of Nb element in ingredient design, thus refined crystalline strengthening and inhibition coarse grains on surface.In addition, ingredient designs
In also added a certain amount of V and N, at steel plate thickness surface, after deformation strain hardening and heat treatment after organization softening the most
The Carbonitride Precipitation reinforcing in serious place, V is the most obvious, thus it is hard higher than center portion to maintain base material deformation rear surface hardness
The performance characteristics of degree.Meanwhile V and N can be precipitated under the conditions of lower temperature, it is thus possible to reduce heat treatment cost.Target is aobvious
Micro-assembly robot control is granular bainite, has taken into account the intensity and plasticity of steel, it is thus possible to further decrease and be brought by residual stress
Heat treatment cost.
In conclusion the embodiment of the present invention is by reducing the difference of hardness of weld seam and its heat affected area and base material, improving steel plate
Surface hardness reduces the Large Inclusions in steel and improves fatigue behaviour in terms of reducing residual stress this four after molding.
Above-mentioned technical proposal in order to better understand, in conjunction with appended figures and specific embodiments to upper
Technical solution is stated to be described in detail.
The vehicle structure steel of excelling in fatigue property provided in an embodiment of the present invention, in terms of quality %, comprising: C:
0.07%-0.15%, Si:0.1%-0.2%, Mn:1.0%-2.0%, P :≤0.015%, S :≤0.004%, Al :≤
0.04%, N:0.0040%-0.0070%, Re:0.1%-0.4%, V:0.10%-0.20%, Nb:0.02%-0.06%,
Remaining is Fe and inevitable impurity.
Further, in terms of quality %, also contain Ni:0.1%-0.4%, Cr:0.25%-0.45%, Mo:0.1%-
0.4%, B: any one in≤0.0008% or two kinds.
In the present embodiment, the C element in ingredient and Mn element are mainly used to solution strengthening, thus proof strength.Ingredient
The Re:0.1%-0.4% (mass fraction) added in design, it is ensured that spherical rare-earth sulfide can replace ribbon completely
MnS be mingled with.In thermal processing distortion, spherical rare-earth sulfide is still able to maintain tiny spherical shape or spindle, and compared with
It is evenly distributed in steel, thus eliminates the ribbon MnS along steel rolling directional spreding being originally present, and then improve
The fatigue behaviour of steel.The Ni:0.1%-0.4%, Cr:0.25%-0.45%, Mo:0.1%- added in ingredient design
0.4%, B: any one in≤0.0008% or two kinds, it is ensured that commissure microscopic structure is lath bayesian after welding
The microscopic structure of body, heat affected area is granular bainite microstructure, and heat affected area is worked as with strength of parent and Plastic phase, to improve
The intensity and toughness of base material.In addition, also added the V element and N element of certain content in ingredient design, to guarantee in hot rolling
In the stage, V, N are with nanoscale nitride form disperse educt, it is thus achieved that the high intensity of steel plate.During heat treatment, also can
It is further precipitated, makes up the organization softening of heat treatment.In addition, also added the Nb element of certain content in ingredient design.Nb exists
It is mainly used for inhibiting coarse grains on surface in steel, and can be improved hot-rolled temperature, is conducive to the homogenization of ingredient and the control of template.
Referring to Fig. 1, the manufacturing method of the vehicle structure steel of excelling in fatigue property provided in an embodiment of the present invention, comprising:
Step S110: slab is smelted and is cast as according to the component content of above-mentioned vehicle structure steel；
Step S120: slab is heated；
This step is specifically described, step S120 is specifically included:
Two-part heating is carried out to slab, soaking temperature is 1200 DEG C -1280 DEG C, and the total time inside furnace of steel billet is
200min-260min。
In the present embodiment, soaking temperature is 1200 DEG C -1280 DEG C, ensure that the homogeneity of ingredient.
Step S130: the slab after heating is rolled；
This step is specifically described, step S130 is specifically included:
Roughing and finish rolling are successively carried out to the slab after heating.
Specifically, during successively carrying out roughing and finish rolling to the slab after heating, roughing uses 6 passages, often
The equal de-scaling of passage；The control of first passage dependent variable is 0.2 hereinafter, the control of remaining passage dependent variable is below 0.45；Roughing outlet
Temperature is controlled at 1150 DEG C -1100 DEG C；Finish rolling uses 7 passages, and dependent variable control is 0.2 hereinafter, finish rolling start rolling temperature per pass
It is 950 DEG C -1000 DEG C, finish rolling finishing temperature is 850 DEG C -950 DEG C, and hot rolling plate thickness is not more than 6mm.
In the present embodiment, finish rolling finishing temperature is 850 DEG C -950 DEG C, ensure that the uniformity of austenite ingredient.
Step S140: cooling down the slab after rolling, obtains vehicle structure steel.
Specifically, during cooling down to the slab after rolling, cooling velocity is 30 DEG C/s-100 DEG C/s, volume
Taking temperature is 550 DEG C -650 DEG C.
In the present embodiment, coiling temperature is 550 DEG C -650 DEG C, it is ensured that nanoscale precipitated phase is precipitated and obtains single-phase grain
Shape bainite structure.
After obtaining vehicle structure steel, further includes:
Pickling is carried out with steel to vehicle structure.
Referring to fig. 2, the manufacturing method of the automobile structure of excelling in fatigue property provided in an embodiment of the present invention, comprising:
Step S210: by the vehicle structure steel manufactured by above-mentioned manufacturing method using radius of curvature R as plate thickness
2-5 times of bending forming, the Vickers hardness at steel plate bending position plate thickness center with away from the Vickers hardness within the 0.4mm of surface most
The difference of high level be 50-100 point, steel plate heat treatment after crooked position plate thickness center Vickers hardness with away from surface 0.4mm within
The difference of peak of Vickers hardness remain as 50-100 point.
In embodiments of the present invention, steel pipe is manufactured with the steel that above-mentioned composition and production technology manufacture, and is become by room temperature
Be formed as torsion beam structural member as shown in Figure 3.The manufacture of steel pipe uses high frequency induction welding, electric resistance welding or Laser Welding.The knot
Section difference in component at A and at B is as shown in Figure 3.From figure 3, it can be seen that section shape at both ends close to circle,
Central part has carried out 2-5 times of the bending machining that radius of curvature R is plate thickness.After bending machining, steel plate surface layer is due to that should be hardened
Change hardness obviously rise, the strain hardening of steel plate thickness center is smaller, hardness rise it is also small, hardness before being deformed after with thickness change
Change as shown in Figure 4.When radius of curvature R is less than 2 times of plate thickness, bending deformation at room temperature is more difficult；When bending radius is super
When crossing 5 times, risen by processing hardening bring hardness insufficient.
Step S220: tempering parameter be 12000-17000 under conditions of, to the vehicle structure steel after bending forming into
Row heat treatment.
In the present embodiment, tempering parameter λ is obtained by formula λ=T (20+log (t)).Wherein, T is absolute temperature, absolutely
The range of temperature T is 350 DEG C -550 DEG C；T is chronomere, is hour.
Sample after bending is heat-treated, strain hardening caused by cold working is restored, and tissue softens again.But
It is that during heat treatment, the pick-up behavior of the second phase will make up organization softening caused by heat treatment.It is especially bright in strain hardening
Aobvious surface location, along with the recovery of dislocation, be precipitated it is more abundant, hardness before heat treatment after with thickness variation such as Fig. 4
It is shown.Studies have shown that when heat treatment parameter is lower than 12000 or higher than 17000, respectively due to insufficient and precipitation is precipitated slightly in generation
Change, cause steel plate be heat-treated after crooked position plate thickness center Vickers hardness with away from the Vickers hardness highest within the 0.4mm of surface
Value difference is lower than 50 points.
Embodiment 1
The chemical constituent of the 800MPa grades of automobile structure steel of tension of excelling in fatigue property provided in an embodiment of the present invention
And corresponding content is referring to table 1:
Table 1 tests steel chemical composition (mass fraction %, surplus are Fe and inevitable impurity)
By the steel of heterogeneity shown in table 1, in 1150 DEG C of -1280 DEG C of reheatings after smelting, execute shown in table 2
Production technology obtains the steel plate that thickness is less than 6mm.Lateral JIS 5# tensile sample is taken, test data is as shown in table 2.
2 processing parameter of table and mechanical property
As shown in figure 5, implementing bending machining to obtained steel plate, the fatigue specimen of U-shaped is made, bending radius is in plate thickness
2-6 times.Sample segment implements 30 minutes stress relief annealings, tempering parameter λ=15249 at 500 DEG C.
As shown in fig. 6, one end of U-shaped test piece is fixed on pedestal, the other end carries out loading-unloading circulation.Circulate in 5
Ten thousand test pieces for occurring below crackle are denoted as X, are denoted as √ in 50,000 times or more 100,000 test pieces for occurring below crackle, and 100,000 times
Above 200,000 test pieces for occurring below crackle are denoted as ⊙, and the test piece of 200,000 times or more generation crackles is denoted as △, as shown in table 3.
In addition, the hardness at plate thickness center and the position of range curvature surface 0.4mm is measured using the microhardness testers of 200gf load, it is poor
Value indicates with H, as shown in table 3.
| No. | Radius of curvature R | Annealing | Fatigue experiment | □H |
| 1 | 5.0 | Nothing | √ | 160 |
| 2 | 4.0 | Have | ⊙ | 80 |
| 3 | 3.5 | Nothing | √ | 140 |
| 4 | 2.0 | Have | □ | 95 |
| 5 | 3.5 | Have | X | 40 |
| 6 | 1.0 | Have | X | 40 |
| 7 | 6.0 | Nothing | - | Crackle |
| 8 | 4.0 | Have | □ | 85 |
Table 3U shape test piece fatigue experiment result and H
As shown in table 3, the H of NO.1-No.4, No.8 are all larger than 50, and fatigue experiment result is good.Especially No.2 and
Excellent fatigue behaviour is obtained after No.8 annealing.No.5 carbon content is lower than 0.07%, and H is lower than 50 after being bent and annealing, therefore
Poor fatigue properties.Less than 2.0 times plate thickness of No.6 bending radius, deformation is insufficient, causes H lower than 50, poor fatigue properties.No.7
Bending radius is greater than 5.0, produces crackle after bending, can not carry out subsequent anneal and fatigue experiment.
Embodiment 2
By 0.12%C-0.15Si-1.5%Mn-0.04%Nb-0.30%Re-0.10%V-0.25%Mo-0.00 70N-
After the hot rolled steel plate of 2.5mm is made in the steel of surplus Fe, tubulation becomes the welded tube of ф 130 (mm), subsequent Pressing Deformation, so that curved
Bent outer radius is annealed in 10mm using different annealing.The residual stress of sample obtained by being measured using X-ray, is adopted
It, will with the plate thickness core rigidities of micro-vickers hardness instrument (load 200gf) measurement section and the hardness of the position away from surface 0.4mm
Its difference is denoted as H.Then, torsional fatigue experiment is carried out, crackle is denoted as X less than 50,000 times when occurring, between 50,000 times to 100,000 times
It is denoted as √, is denoted as ⊙ 100,000 times to 200,000 times, is denoted as 200,000 times or more.The results are shown in Table 4.
Table 4
As shown in Table 4, although the residual stress of No.1 and No.2 is high, H is 50 or more, therefore fatigue experiment result is good
It is good.The residual stress of No.3 and No.4 is low, and H is 50 or more, therefore excelling in fatigue property, especially No.4 fatigue are more than
200000 times.The tempering parameter of No.5 is big, and residual stress is low, but H 50 hereinafter, fatigue behaviour is lower.
Embodiment 3
For (a) 0.12%C-0.15Si-1.5%Mn-0.04%Nb-0.30%Re-0.10%V-0.30%Cr-
The steel and (b) 0.12%C-0.15Si-1.5%Mn-0.06%Nb-0.30%Re-0.30%Cr- of 0.0070N- surplus Fe
After the hot rolled steel plate of 2.5mm is made in the steel of 0.0030N-- surplus Fe, bending deformation, bending radius 10mm are carried out.It is then right
Bend specimen keeps the temperature 30 minutes at 500 DEG C, stress relief annealing.Bending examination is measured using micro-vickers hardness instrument (load 200gf)
The hardness of the plate thickness core rigidities and the position away from surface 0.4mm of sample and bending after annealing sample section, as a result such as Fig. 7 and Fig. 8
It is shown.It can be seen from figure 7 that (a) steel of the embodiment of the present invention, processing and annealing rear surface layer hardness are all higher, and with
Plate thickness core rigidities difference is larger, and a large amount of precipitations of the VN on steel plate surface layer effectively counteract the annealing of microscopic structure in annealing process
Softening.In contrast, comparative example (b) steel, although plate thickness core rigidities and steel of the embodiment of the present invention are same, as caused by annealing
Hardness reduces larger.
[technical effect]
1, it selects C content range for 0.07%-0.15%, and adds a certain amount of solution strengthening element, thus guaranteeing
While weld strength, also ensure that plastic property of weld bead not less than base material, thus reduces weld seam and its heat affected area and base material
Difference of hardness.In addition, being added to alloying element V in ingredient design, Low Temperature Heat Treatment is used after forming, the carbonitride containing V is zero
Part surface is largely precipitated, hereby it is ensured that surface hardness.Meanwhile also added Re element, size is tiny, the spherical shape being evenly distributed
Rare-earth sulfide banded MnS can be replaced to be mingled with completely, in thermal processing distortion, spherical rare-earth sulfide remains to protect
Hold tiny spherical shape or spindle, and it is more uniform be distributed in steel, thus eliminate rolling along steel of being originally present
The ribbon MnS of directional spreding processed, and then improve the fatigue behaviour of steel.Ti element is not added, avoids TiN type impurity
It generates, thus reduces the Large Inclusions in steel.In addition, also used in ingredient it is more improve harden ability element, as C,
Mn, Cr and Mo etc., in process air cooler after welding, weld dimensions tissue is close with base material based on bainite, because
This its mechanical property is also close with base material, thus improves fatigue behaviour.In addition, ingredient design in additionally use higher C and
Mn content, and it is added to a certain amount of Cr element and Mo element.In addition, a certain amount of Ni or B of addition may be selected, also with solid solution
Strengthen；It also added a certain amount of Nb element in ingredient design, thus refined crystalline strengthening and inhibition coarse grains on surface.In addition, at setting up separately
Also added a certain amount of V and N in meter, at steel plate thickness surface, after deformation strain hardening and heat treatment after organization softening most
Carbonitride Precipitation reinforcing for serious place, V is the most obvious, thus maintains base material deformation rear surface hardness and be higher than center portion
The performance characteristics of hardness.Meanwhile V and N can be precipitated under the conditions of lower temperature, it is thus possible to reduce heat treatment cost.Target
Microstructures Control is granular bainite, has taken into account the intensity and plasticity of steel, it is thus possible to further decrease by residual stress band
The heat treatment cost come.
In conclusion the embodiment of the present invention is by reducing the difference of hardness of weld seam and its heat affected area and base material, improving steel plate
Surface hardness reduces the Large Inclusions in steel and improves fatigue behaviour in terms of reducing residual stress this four after molding.
2, the embodiment of the present invention has selected high-temperature phase-change tissue-granular bainite microstructure as destination organization, is guaranteeing by force
Under the precondition of degree, the forming property of base material is improved.In addition, also by using (350 DEG C -550 under lower temperature conditions
DEG C) heat treatment process eliminate residual stress, further improve fatigue behaviour.
The embodiment of the invention provides a kind of excelling in fatigue property, lower-cost, the tension 800MPa rank of heat treatment
The manufacturing method of steel and the method for manufacturing tubular type punching type torsion beam using the material.Use steel provided in an embodiment of the present invention
Material, and according to the fatigue behaviour of the automobile structure of method provided in an embodiment of the present invention manufacture better than such production currently on the market
The fatigue behaviour of product, and cost is relatively low for heat treatment.
Although preferred embodiments of the present invention have been described, it is created once a person skilled in the art knows basic
Property concept, then additional changes and modifications may be made to these embodiments.So it includes excellent that the following claims are intended to be interpreted as
It selects embodiment and falls into all change and modification of the scope of the invention.
Obviously, various changes and modifications can be made to the invention without departing from essence of the invention by those skilled in the art
Mind and range.In this way, if these modifications and changes of the present invention belongs to the range of the claims in the present invention and its equivalent technologies
Within, then the present invention is also intended to include these modifications and variations.
Claims (9)
1. a kind of vehicle structure steel, which is characterized in that in terms of quality %, comprising: C:0.07%-0.15%, Si:0.1%-
0.2%, Mn:1.0%-2.0%, P :≤0.015%, S :≤0.004%, Al :≤0.04%, N:0.0040%-0.0070%,
Re:0.1%-0.4%, V:0.10%-0.20%, Nb:0.02%-0.06%, remaining is Fe and inevitable impurity.
2. vehicle structure steel as described in claim 1, which is characterized in that in terms of quality %, also contain Ni:0.1%-
0.4%, Cr:0.25%-0.45%, Mo:0.1%-0.4%, B: any one in≤0.0008% or two kinds.
3. a kind of manufacturing method of vehicle structure steel characterized by comprising
Slab is smelted and is cast as according to the component content of vehicle structure steel as claimed in claim 1 or 2；
The slab is heated；
Slab after heating is rolled；
Slab after rolling is cooled down, vehicle structure steel is obtained.
4. manufacturing method as claimed in claim 3, which is characterized in that described to be heated to the slab, comprising:
Two-part heating is carried out to the slab, soaking temperature is 1200 DEG C -1280 DEG C, and the total time inside furnace of steel billet is
200min-260min。
5. manufacturing method as claimed in claim 3, which is characterized in that the slab after described pair of heating rolls, comprising:
Roughing and finish rolling are successively carried out to the slab after heating.
6. manufacturing method as claimed in claim 5, which is characterized in that the slab after described pair of heating successively carries out roughing
During finish rolling, the roughing uses 6 passages, per pass equal de-scaling；First passage dependent variable control 0.2 hereinafter, its
Remaining passage dependent variable control is below 0.45；Roughing outlet temperature is controlled at 1150 DEG C -1100 DEG C；The finish rolling uses 7 passages,
0.2 hereinafter, finish rolling start rolling temperature is 950 DEG C -1000 DEG C, finish rolling finishing temperature is 850 DEG C -950 for dependent variable control per pass
DEG C, hot rolling plate thickness is not more than 6mm.
7. manufacturing method as claimed in claim 3, which is characterized in that the slab after described pair of rolling carries out cooling mistake
Cheng Zhong, cooling velocity are 30 DEG C/s-100 DEG C/s, and coiling temperature is 550 DEG C -650 DEG C.
8. manufacturing method as claimed in claim 3, which is characterized in that it is described obtain vehicle structure steel after, further includes:
Pickling is carried out with steel to the vehicle structure.
9. a kind of manufacturing method of automobile structure characterized by comprising
By the vehicle structure steel manufactured by the manufacturing method as described in any one of claim 3-8 with bending radius
R is 2-5 times of bending forming of plate thickness；
Under conditions of tempering parameter is 12000-17000, the vehicle structure after bending forming is heat-treated with steel.
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| CN111519105A (en) * | 2020-05-12 | 2020-08-11 | 首钢集团有限公司 | Automobile component steel, preparation method thereof and automobile component |
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