CN102560253B - Manufacturing method of high-quality cold heading steel with uniform structure property - Google Patents
Manufacturing method of high-quality cold heading steel with uniform structure property Download PDFInfo
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- CN102560253B CN102560253B CN201210064412.2A CN201210064412A CN102560253B CN 102560253 B CN102560253 B CN 102560253B CN 201210064412 A CN201210064412 A CN 201210064412A CN 102560253 B CN102560253 B CN 102560253B
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Abstract
The invention belongs to the technical field of medium carbon cold heading steel wire production, and relates to a manufacturing method of high-quality cold heading steel with a uniform structure property. The cold heading steel comprises the following chemical compositions by weight percent: 0.25 to 0.45% of C, 0.45 to 0.9% of Mn, 0.05 to 0.40% of Si, 0.70 to 1.50% of Cr, 0.03 to 0.50% of Mo, 0.015 to 0.045% of Alt, and the balance being Fe and unavoidable impurities. In a rolling process, a casting blank is heated, the billet taping temperature is 900 to 1150 DEG C, the final finish rolling temperature is 700 to 860 DEG C, and the spinning temperature is 800 to 880 DEG C. In a Stelmor air-cooled wire controlled cooling process, the casting blank is cooled to 500 to 700 DEG C at a cooling rate of more than 5 DEG C/s and then enters a cover, and the cooling rate in the cover is 0.2 to 0.8 DEG C/s. According to the manufacturing method, the traditional controlled rolling and controlled cooling process is reasonably set, and the role of the controlled rolling and controlled cooling process in structure control is fully played, so that the ideal structure is controlled, the cracking problem of the cold heading steel is greatly solved, the pass rate of standard finished products is improved, and the economic efficiency is improved.
Description
Technical field
The invention belongs to medium carbon cold heading steel wire production technical field, specifically the manufacture method of the uniform high-quality cold heading steel of a kind of structure property.
Background technology
According to the prediction of Domestic Automotive Industry association, the development based on car load during " 12 " is far away prior to fastening parts of automobiles, and 5 years from now on by the high-speed development period that is fastening parts of automobiles.Because imported materials and items hardening capacity is good, high purity and the advantage such as assembling is stable, high level fastening piece market is occupied by external product for a long time.
In steel enterprise, add perlite in the wire production of Main Tissues take ferrite at home, overlapped points and non-overlapping in process of cooling cooling rate inhomogeneous.Non-overlapping some place: obtain the ferritic structure of coarse grains, and tissue odds is even, can causes the reduction of cold heading performance.Overlapped points position: go out to cover the higher phase transformation of temperature and not yet finish, in follow-up collection volume air cooling, further phase transformation occurs and finally produce bainite and add a small amount of ferrite and pearlite tissue.Wire rod tissue odds is even, and mechanical property is also not quite similar; This uses to downstream client's processing and has brought very large inconvenience, causes the problems such as cold-heading processing cracking and working modulus are low.
Summary of the invention
Technical problem to be solved by this invention is, overcome the shortcoming of prior art, the manufacture method of the uniform high-quality cold heading steel of a kind of structure property is provided, by controlled rolling and the Controlled cooling process of reasonable setting Cold Heading Steel Wire, make full use of the recrystallize of finish to gauge stage austenite crystal, refinement original austenite grains, rationally set Stanermo wind-cooling linear technique simultaneously, obtain take bainite as the main uniform original wire rod of structure property, in subsequent heat treatment, obtain uniform Spheroidizing Annealing tissue, effectively reduced the problem of Cracking of cold heading steel processing.
The technical scheme that the present invention solves above technical problem is:
A manufacture method for the uniform high-quality cold heading steel of structure property, operational path is: electrosmelting → refining → continuous casting → steel billet ball blast, reconditioning → strand heating → de-scaling → roughing → in roll → finish rolling → weave silk → Stanermo wind-cooling linear → collection roll up → tie up sign → check → warehouse-in;
Cold heading steel chemical composition is by weight percentage: C:0.25～0.45%, Mn:0.45～0.90%, Si:0.05～0.40%, Cr:0.70～1. 50%, Mo:0.03～0.50%, Alt:0.015～0.045%(represents full aluminium), all the other are Fe and inevitable impurity;
Rolling technology: 900～1150 ℃ of steel billet tapping temperatures after strand heating, finish rolling finishing temperature: 700～860 ℃, laying temperature: 800～880 ℃;
Stanermo wind-cooling linear cooling control technology: enter cover with after 5 ℃/s～10 ℃/s cooling rate is cooled to 500～700 ℃, in cover, cooling rate is 0.2～0.8 ℃/s, and going out to cover temperature is 460～630 ℃.
Like this, enter the front first rapid cooling of cover, avoid occurring ferrite and pearlitic transformation; After rapid cooling, enter to cover slow cooling with lesser temps, successively there is bainite transformation in non-overlapping point and overlapped points, obtains the uniform wire rod of structure property.Middle (being non-overlapping point): in the rapid cooling stage, phase transition process is crossed ferrite and pearlite district substantially; Enter after cover with lesser temps, bainitic transformation occurs; Finally obtain take bainite as main a small amount of ferrite, the pearlitic tissue of adding.Overlapped points: with cooling compared with slow cooling speed, a small amount of ferrite, pearlitic transformation occur.Control out cover temperature and arrive bainite by transition temperature, in follow-up collection volume air cooling, the final generation take bainite as master of further phase transformation occurs and add a small amount of ferrite, pearlitic tissue.Controlling in cover after first slow cooling rapid cooling, to obtain bainite be mainly to add a small amount of ferrite, pearlitic tissue, although overlapped points and non-overlapping some place exist the temperature difference, logical circle is organized identical.The wire rod of this uniform formation, formerly Spheroidizing Annealing can well be applied in cold-heading complete processing after drawing again.
The technical scheme that the present invention further limits is:
The manufacture method of the uniform high-quality cold heading steel of aforesaid structure property, cold heading steel chemical composition is by weight percentage: C:0.35%, Mn:0.63%, Si:0.22%, Cr:0.97%, Mo:0.16%, P:0.011%, S:0.002%, Cu:0.07%, Ni:0.05%, Alt:0.026%, all the other are Fe and inevitable impurity;
Rolling technology: 1060 ℃ of steel billet tapping temperatures after strand heating, finish rolling finishing temperature: 830 ℃, laying temperature: 825 ℃;
Stanermo wind-cooling linear cooling control technology: 6.5 ℃/s of the air-cooled cooling rate of steel billet overlapped points, 6.5 ℃/s of air-cooled cooling rate in the middle of steel billet, steel billet overlap joint is clicked and entered 680 ℃ of cover temperature, in the middle of steel billet, enter to cover 650 ℃ of temperature, 0.34 ℃/s of cooling rate in steel billet overlapped points cover, 0.82 ℃/s of cooling rate in steel billet intermediate cap, steel billet overlap joint is pointed out 610 ℃ of cover temperature, goes out to cover 480 ℃ of temperature in the middle of steel billet;
Prepared cold heading steel mechanical property is: tensile strength: 950Mpa, and unit elongation: 17%, relative reduction in area: 51%, Vickers' hardness: 296Hv.
The manufacture method of the uniform high-quality cold heading steel of aforesaid structure property, cold heading steel chemical composition is by weight percentage: C:0.35%, Mn:0.65%, Si:0.25%, Cr:0.98%, Mo:0.17%, P:0.019%, S:0.006%, Cu:0.08%, Ni:0.04%, Alt:0.031%, all the other are Fe and inevitable impurity;
Rolling technology: 1050 ℃ of steel billet tapping temperatures after strand heating, finish rolling finishing temperature: 835 ℃, laying temperature: 820 ℃;
Stanermo wind-cooling linear cooling control technology: coil 6.7 ℃/s of the air-cooled cooling rate of overlapped points, 6.8 ℃/s of air-cooled cooling rate in the middle of coiling, coil overlap joint and click and enter 685 ℃ of cover temperature, in the middle of coiling, enter to cover 650 ℃ of temperature, coil 0.35 ℃/s of cooling rate in overlapped points cover, coil 0.81 ℃/s of cooling rate in intermediate cap, coil overlap joint and point out 610 ℃ of cover temperature, in the middle of coiling, go out to cover 485 ℃ of temperature;
Prepared cold heading steel mechanical property is: tensile strength: 955Mpa, and unit elongation: 16%, relative reduction in area: 49%, Vickers' hardness: 298Hv.
The manufacture method of the uniform high-quality cold heading steel of aforesaid structure property, cold heading steel specification is Φ 5.5～26mm.
The invention has the beneficial effects as follows: the present invention rationally sets existing cooling controlling and rolling controlling process, give full play to the effect of cooling controlling and rolling controlling process aspect organizational controls, control out desirable tissue, significantly reduce Cold Heading Crack of Cold Heading Steel Wire Rod problem, improve the qualification rate of standardized component finished product, increase economic efficiency.
Accompanying drawing explanation
Fig. 1 is the microstructure picture of the embodiment of the present invention 1 wire rod overlapped points position.
Fig. 2 is the microstructure picture at the embodiment of the present invention non-overlapping point of 1 wire rod place.
Embodiment
embodiment
The manufacture method of the uniform high-quality cold heading steel of a kind of structure property, take to control steel billet composition and adopt different cooling controlling and rolling controlling process to carry out the uniform cold heading steel of production structure property according to different size, main production process route is: electrosmelting → refining → continuous casting → steel billet ball blast, reconditioning → strand heating → de-scaling → roughing → in roll → finish rolling → weave silk → Stanermo wind-cooling linear → collection roll up → tie up sign → check → warehouse-in.Cold Heading Steel Wire specification Φ 5.5～26mm.
It is the square billet of 150 × 150mm that embodiment 1 adopts blank section, and trimmed size is Φ 8mm, and composition is as shown in table 1, steel billet tapping temperature is 1060 ℃, laying temperature is 825 ℃, and rolling technology and Stanermo wind-cooling linear cooling control technology are as shown in table 2, and mechanical property is as shown in table 3.
It is the square billet of 150 × 150mm that embodiment 2 adopts blank section, and trimmed size is Φ 12mm, and composition is as shown in table 1, steel billet tapping temperature is 1050 ℃, laying temperature is 820 ℃, and rolling technology and Stanermo wind-cooling linear cooling control technology are as shown in table 2, and mechanical property is as shown in table 3.
Table 1 chemical composition (wt, %)
| Composition | C | Mn | Si | Cr | P | S | Cu | Ni | Mo | Alt |
| Embodiment 1 | 0.35 | 0.63 | 0.22 | 0.97 | 0.011 | 0.002 | 0.07 | 0.05 | 0.16 | 0.026 |
| Embodiment 2 | 0.35 | 0.65 | 0.25 | 0.98 | 0.019 | 0.006 | 0.08 | 0.04 | 0.17 | 0.031 |
In table 1, in table ingredients listed, all the other are Fe and micro impurity element.
Table 2 cooling controlling and rolling controlling process
" centre " i.e. " non-overlapping point " in table 2.
Table 3 mechanical property
| ? | Tensile strength MPa | Unit elongation % | Relative reduction in area % | Vickers' hardness Hv |
| Embodiment 1 | 950 | 17 | 51 | 296 |
| Embodiment 2 | 955 | 16 | 49 | 298 |
Fig. 1 is the microstructure picture of embodiment 1 wire rod overlapped points position, and Fig. 2 is the microstructure picture at the embodiment non-overlapping point of 1 wire rod place, by Fig. 1 and the visible overlapped points of Fig. 2 and non-overlapping point organize identical, performance is even.
In addition to the implementation, the present invention can also have other embodiments.All employings are equal to the technical scheme of replacement or equivalent transformation formation, all drop on the protection domain of requirement of the present invention.
Claims (4)
1. a manufacture method for the uniform high-quality cold heading steel of structure property, operational path is: electrosmelting → refining → continuous casting → steel billet ball blast, reconditioning → strand heating → de-scaling → roughing → in roll → finish rolling → weave silk → Stanermo wind-cooling linear → collection roll up → tie up sign → check → warehouse-in;
Described cold heading steel chemical composition is by weight percentage: C:0.25～0.45%, and Mn:0.45～0.90%, Si:0.05～0.40%, Cr:0.70～1. 50%, Mo:0.03～0.50%, Alt:0.015～0.045%, all the other are Fe and inevitable impurity;
Rolling technology: 900～1150 ℃ of steel billet tapping temperatures after strand heating, finish rolling finishing temperature: 700～860 ℃, laying temperature: 800～880 ℃;
It is characterized in that:
Stanermo wind-cooling linear cooling control technology: enter cover with after 5 ℃/s～10 ℃/s cooling rate is cooled to 500～700 ℃, in cover, cooling rate is 0.2～0.8 ℃/s, and going out to cover temperature is 460～630 ℃.
2. the manufacture method of the uniform high-quality cold heading steel of structure property as claimed in claim 1, it is characterized in that: described cold heading steel chemical composition is by weight percentage: C:0.35%, Mn:0.63%, Si:0.22%, Cr:0.97%, Mo:0.16%, P:0.011%, S:0.002%, Cu:0.07%, Ni:0.05%, Alt:0.026%, all the other are Fe and inevitable impurity;
Rolling technology: 1060 ℃ of steel billet tapping temperatures after strand heating, finish rolling finishing temperature: 830 ℃, laying temperature: 825 ℃;
Stanermo wind-cooling linear cooling control technology: coil 6.5 ℃/s of the air-cooled cooling rate of overlapped points, 6.5 ℃/s of air-cooled cooling rate in the middle of coiling, coil overlap joint and click and enter 680 ℃ of cover temperature, in the middle of coiling, enter to cover 650 ℃ of temperature, coil 0.34 ℃/s of cooling rate in overlapped points cover, coil 0.82 ℃/s of cooling rate in intermediate cap, coil overlap joint and point out 610 ℃ of cover temperature, in the middle of coiling, go out to cover 480 ℃ of temperature;
Prepared cold heading steel mechanical property is: tensile strength: 950Mpa, and unit elongation: 17%, relative reduction in area: 51%, Vickers' hardness: 296Hv.
3. the manufacture method of the uniform high-quality cold heading steel of structure property as claimed in claim 1, it is characterized in that: described cold heading steel chemical composition is by weight percentage: C:0.35%, Mn:0.65%, Si:0.25%, Cr:0.98%, Mo:0.17%, P:0.019%, S:0.006%, Cu:0.08%, Ni:0.04%, Alt:0.031 %, all the other are Fe and inevitable impurity;
Rolling technology: 1050 ℃ of steel billet tapping temperatures after strand heating, finish rolling finishing temperature: 835 ℃, laying temperature: 820 ℃;
Stanermo wind-cooling linear cooling control technology: coil 6.7 ℃/s of the air-cooled cooling rate of overlapped points, 6.8 ℃/s of air-cooled cooling rate in the middle of coiling, coil overlap joint and click and enter 685 ℃ of cover temperature, in the middle of coiling, enter to cover 650 ℃ of temperature, coil 0.35 ℃/s of cooling rate in overlapped points cover, coil 0.81 ℃/s of cooling rate in intermediate cap, coil overlap joint and point out 610 ℃ of cover temperature, in the middle of coiling, go out to cover 485 ℃ of temperature;
Prepared cold heading steel mechanical property is: tensile strength: 955Mpa, and unit elongation: 16%, relative reduction in area: 49%, Vickers' hardness: 298Hv.
4. the manufacture method of the uniform high-quality cold heading steel of structure property as described in claim 1 or 2 or 3, is characterized in that: described cold heading steel specification is Φ 5.5～26mm.
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