CN103740918A - Heat treatment method of hollow core rod used for tandem rolling set - Google Patents
Heat treatment method of hollow core rod used for tandem rolling set Download PDFInfo
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- CN103740918A CN103740918A CN201310687454.6A CN201310687454A CN103740918A CN 103740918 A CN103740918 A CN 103740918A CN 201310687454 A CN201310687454 A CN 201310687454A CN 103740918 A CN103740918 A CN 103740918A
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Abstract
The invention discloses a heat treatment method of a hollow core rod used for a tandem rolling set. The heat treatment method comprises the following steps: uniformly heating the hollow core rod to be heated in a gas furnace to the temperature of 900 DEG C, wherein the heating time should be ensured for 5-6 hours; after the hollow core rod is removed from the gas furnace, quenching the heated hollow core rod, increasing the cooling capability of water to the hollow core rod while quenching, and then uniformly cooling the internal and external parts; tempering for 18-26 hours at the temperature of 600-640 DEG C, and then discharging the hollow core rod. The heat treatment method solves the problems that the alloy steel hollow core rods with low cost employs a traditional quenching technology so that the hardness of the head, the central section and the tail of the hollow core rod are nonuniform due to insufficient and nonuniform cooling, and the anti-tempering stability is low by comparing with the NO. 4Cr5MoV1Si steel selected by the core rod of the tandem rolling set. The hardness of the obtained hollow core rod is uniform, and compared with the NO. 4Cr5MoV1Si steel, the anti-tempering stability is higher; so that the low alloy steel (30Cr2MoV) is one of the core rod materials. The production cost of the core rod is reduced.
Description
Technical field
The present invention relates to a kind of heat treating method of hollow core rod, particularly, relate to a kind of heat treating method of the hollow core rod for tandem rolling unit.
Background technology
Plug is to produce one of most important warp tool using in the tandem rolling unit of weldless steel tube.Its consumption is larger, and its quality and cost are directly connected to the quality and benefits of seamless steel tube production.And roll seamless steel tube the working conditions of plug is very severe during the course, stress, frictional force and alternating hot and cold stress etc. are being born in its surface.The plug working long hours there will be the defects such as surface heat fatigue cracking, machinery scuffing, flake-off piece, chromium coating damage.Yet can the quality of plug quality, directly have influence on and carry out smoothly in the operation of rolling and can institute's wroughtsteel pipe quality meet standard-required, and the height of steel pipe manufacturing cost.
For many years, the most dependence of the plug import of domestic each seamless steel tube production enterprise, import plug not only price is very expensive, and the time of delivery is difficult to control, to producing, affect, this is seriously restricting the development of China's weldless steel tube industry, therefore, in the urgent need to developing a kind of manufacture method of extensive plug, to meet the demand of domestic market.According to related data analysis, the continuous rolling-tube unit that China has gone into operation and has been about to go into operation has 26 covers, and continuous rolling-tube unit annual production can be calculated according to continuous rolling-tube unit mean consumption 1.0kg/t pipe more than 1,000 ten thousand tons, year consumes nearly 10,000 tons of plug.As can be seen here, along with increasingly sharpening of steel pipe industry competition, reduce production costs, improve productivity effect and become the focus that people pay close attention to, and affect steel pipe's production cost important factor be the cost of plug first.How to improve the quality of plug, reducing plug production cost is problem demanding prompt solution.
Summary of the invention
For above-mentioned deficiency of the prior art, one object of the present invention is to provide a kind of heat treating method of the hollow core rod for tandem rolling unit.
According to an aspect of the present invention, a kind of heat treating method of the hollow core rod for tandem rolling unit is provided, described heat treating method comprises the steps: heating steps, and hollow core rod to be heated is evenly warming up to 900 ℃ in gas furnace, guarantees that be 5～6 hours heat-up time; Quenching step, after hollow core rod goes out gas furnace, quenches to the hollow core rod after heating, when quenching the inside and outside while of hollow core rod cooling, to improve quenchant to the cooling power of hollow core rod and homogeneity; Tempering step is heated to 600～640 ℃ by the hollow core rod after quenching and guarantees tempering 18～26 hours in gas furnace, then makes hollow core rod come out of the stove.
According to embodiments of the invention, in quenching step, quenchant is water.
According to embodiments of the invention, the material of hollow core rod is 30Cr2MoV steel.
According to embodiments of the invention, the cool time is 300s～3600s.
According to embodiments of the invention, the chemical composition of 30Cr2MoV steel is by weight percentage: C0.31%～0.34%, Mn0.4%～0.7%, Si0.17%～0.40%, P≤0.008%, S≤0.003%, Cr2.30%～2.70%, Mo0.60%～0.65%, V0.20%～0.25%, Cu≤0.20%, Sn≤0.064%, As≤0.03%, all the other are iron and inevitable impurity.
According to embodiments of the invention, hollow core rod is of a size of
404.7mm * 140mm * 13500mm.
According to the hollow core rod for tandem rolling unit of the present invention (
404.7mm * 140mm * 13500mm) heat treating method, the hollow core rod hardness obtaining is evenly and have compared with high resistance temper resistance; Low alloy steel (30Cr2MoV) is become manufacture hollow core rod (
404.7mm * 140mm * 13500mm) one of material.In addition, reduced the production cost of plug.
Accompanying drawing explanation
By the description to embodiment of carrying out below in conjunction with accompanying drawing, above-mentioned and/or other object of the present invention and advantage will become apparent, wherein:
Fig. 1 shows the structural representation of the hollow core rod refrigerating device inside of exemplary embodiment of the present invention.
Embodiment
Below in conjunction with embodiment, the heat treating method of the hollow core rod for tandem rolling unit of the present invention is described in detail.
The heat treating method that the invention provides a kind of hollow core rod for tandem rolling unit, this heat treating method comprises: heating process, quenching technology, tempering process and process for cooling.
Specifically, in the step of heating process, for example hollow core rod to be heated 104 need to be put into, in process furnace (, can be gas furnace) and heat, Heating temperature is 900 ℃-1020 ℃, and the heating and thermal insulation time is 5～6h.
In the step of quenching technology, need to the hollow core rod 104 after heating be quenched.Specifically, using water as quenchant, thereby the inside and outside of hollow core rod 104 carried out to cooling raising water to hollow core rod 104 cooling poweies and homogeneity simultaneously, wherein, exterior cooling for hollow core rod 104 adopts quenching cooler conventional in present technology and adopts this area to carry out the conventional existing technique of quenching, and can carry out by hollow core rod refrigerating device inside as shown in Figure 1 for the internal cooling of hollow core rod 104, this hollow core rod refrigerating device inside 100 comprises the pump 102 for delivery of quenchant, for quenchant being delivered to the pipeline 101 of hollow core rod 104 inside and the tensimeter 103 of controlling the pressure of pipeline quenchant, but the present invention is not limited to this.In addition, in the present invention, inside cooling more even of hollow core rod can be made by controlling pipeline 101 diameters of hollow core rod refrigerating device inside 100 and the pressure of tensimeter 103, preferably, the diameter of pipeline can be 80～200mm, and pressure can be controlled in 0.05～2MPa.In addition, the inside of hollow core rod is being carried out when cooling, preferably, the temperature of quenchant water can be controlled at 20 ℃ of left and right.In the present invention, preferably, the cool time can be 300s～3600s.
In the step of tempering process, be heated to 600～640 ℃ of insulation 18～26h.The hollow core rod 104 of the mode that adopts air cooling after to tempering carries out cooling.
In addition, those skilled in the art are known, the chemical composition of 30Cr2MoV steel (GB) standard by weight percentage: C0.26%～0.34%, Mn0.4%～0.7%, Si0.17%～0.40%, P≤0.035%, S≤0.035%, Cr2.30%～2.70%, Mo0.15%～0.25%, V0.10%～0.20%, Cu≤0.20%, Sn≤0.064%.But in the present invention, for improving hardening capacity and the anti-temper resistance of hollow core rod material, preferably, the material of hollow core rod 104 is 30Cr2MoV steel, be: C0.31%～0.34%, Mn0.4%～0.7%, Si0.17%～0.40%, P≤0.008%, S≤0.003%, Cr2.30%～2.70%, Mo0.60%～0.65%, V0.20%～0.25%, Cu≤0.20%, Sn≤0.064%, As≤0.03%, all the other are iron and inevitable impurity.The present invention substitutes the plug of 4Cr5MoV1Si material by the hollow core rod of 30Cr2MoV material, make Cr content reduce to 2.30%～2.70% by 4.50%～5.50%, Mo content reduces to 0.60%～0.65% by 1.00%～1.50%, V content reduces to 0.20%～0.25% by 0.80%～1.20%, through contrast, the present invention has saved the content of the noble alloy elements such as the Cr, the Mo that add in plug material, V, cost-saving more than 50%.
In addition, the size of hollow core rod 104 of the present invention can be internal diameter
404.7mm * wall thickness 140mm * length 13500mm.
The present invention by adopt to hollow core rod (
404.7mm * 140mm * 13500mm) it is cooling that endoporus is controlled flow, utilize water temperature, flow velocity to improve water to hollow large plug cooling power to cooling power impact, solved that low-cost alloy steel hollow core rod adopts tradition to quench due to cooling deficiency, inhomogeneously causes hollow core rod head, middle part, afterbody hardness is inhomogeneous and anti-temper resistance phenomenon on the low side, the hollow core rod after air cooling has been carried out to hardness and detect head, centre, afterbody hardness fluctuations≤30HB.
In addition, the present invention obtains hollow core rod hardness evenly and have compared with high resistance temper resistance; Low alloy steel (30Cr2MoV) is become and manufacture one of plug material.
In addition, method of the present invention has reduced the production cost of plug.
Example 1
To the hollow core rod 104 of 30Cr2MoV steel (
404.7mm * 140mm * 13500mm) heat-treat.Wherein, the chemical composition of 30Cr2MoV steel is by weight percentage: C0.31%～0.34%, Mn0.4%～0.7%, Si0.17%～0.40%, P≤0.008%, S≤0.003%, Cr2.30%～2.70%, Mo0.60%～0.65%, V0.20%～0.25%, Cu≤0.20%, Sn≤0.064%, As≤0.03%, all the other are iron and inevitable impurity.
This hollow core rod 104 is placed in to gas furnace and is heated to after 900 ℃, insulation 6h.Hollow core rod 104 after heating is quenched, cool time is 720s, exterior cooling for hollow core rod 104 adopts quenching cooler conventional in present technology and adopts this area to carry out the conventional existing technique of quenching, for hollow core rod 104 internal coolings, adopt the inside of 100 pairs of hollow core rods of hollow core rod refrigerating device inside to carry out cooling, these hollow core rod 104 refrigerating device insides 100 comprise for water (temperature is 20 ℃) being delivered to the pipeline 101 of hollow core rod inside, for delivery of the pump 102 of quenchant and the tensimeter 103 of controlling the pressure of quenchant in pipeline 1, the diameter of the pipeline 101 in hollow core rod refrigerating device inside 100 is 100mm simultaneously, the pressure of tensimeter 103 is 0.5MPa.Hollow core rod 104 after quenching is heated to 610 ℃, tempering 26h.Hollow core rod 104 after tempering is carried out to air cooling.Hollow core rod after thermal treatment is carried out to Mechanics Performance Testing, and its result is as shown in table 1.
To example 1
To 4Cr5MoV1Si steel core bar (internal diameter
380mm * length 13500mm) heat-treat.
Wherein, the chemical composition of 4Cr5MoV1Si (GB) number steel is by weight percentage: C0.30%～0.38%, Mn≤0.60%, Si0.70%～1.40%, P≤0.005%, S≤0.003%, Cr4.50%～5.50%, Mo1.00%～1.50%, V0.80%～1.20%, Cu≤0.20%, Sn≤0.064%, As≤0.03%, all the other are iron and inevitable impurity.
This plug is placed in to process furnace and is heated to after 1030 ℃, insulation 6h.Plug after heating is quenched in oil, and the cool time is 2.5 hours.Plug after quenching is heated to 610 ℃, tempering 26h, double tempering.Plug after tempering is carried out to air cooling.Plug after thermal treatment is carried out to Mechanics Performance Testing, and its result is as shown in table 1.
Table 1 normal temperature mechanical property contrast table
From table 1, the data of demonstration can be found out, the normal temperature ballistic work of 30Cr2MoV steel hollow core rod and mechanical property are better than normal temperature ballistic work and the mechanical property of 4Cr5MoV1Si steel core bar.
Example 1 and plug that example 1 is obtained are sampled and do anti-temper resistance test, and result is as shown in table 2:
The anti-temper resistance contrast table of table 2
The data that show from table 2 can be found out: the anti-qualitative 4Cr5MoV1Si of the being better than steel core bar that stabilizes of 30Cr2MoV steel hollow core rod.
In sum, because impact value and anti-temper resistance index are to weigh the key technical index of continuous mill plug quality, the large hollow core rod of 30Cr2MoV steel (
404.7mm * 140mm * 13500mm) key technical index be better than the large plug of 4Cr5MoV1Si steel (
385.1mm * 13500mm).Therefore, 30Cr2MoV steel can become one of large hollow core rod material of manufacture continuous mill.
Claims (6)
1. for a heat treating method for the hollow core rod of tandem rolling unit, described heat treating method comprises the steps:
Heating steps is evenly warming up to 900 ℃ by hollow core rod to be heated in gas furnace, guarantees that be 5～6 hours heat-up time;
Quenching step, after hollow core rod goes out gas furnace, quenches to the hollow core rod after heating, when quenching the inside and outside while of hollow core rod cooling, to improve the cooling uniformity of quenchant to hollow core rod;
Tempering step is heated to 600～640 ℃ by the hollow core rod after quenching and guarantees tempering 18～26 hours in gas furnace, then makes hollow core rod come out of the stove.
2. heat treating method according to claim 1, wherein, in quenching step, quenchant is water.
3. heat treating method according to claim 1, wherein, the material of hollow core rod is 30Cr2MoV steel.
4. heat treating method according to claim 1, wherein, the cool time is 300s～3600s.
5. heat treating method according to claim 3, wherein, the chemical composition of 30Cr2MoV steel is by weight percentage: C0.31%～0.34%, Mn0.4%～0.7%, Si0.17%～0.40%, P≤0.008%, S≤0.003%, Cr2.30%～2.70%, Mo0.60%～0.65%, V0.20%～0.25%, Cu≤0.20%, Sn≤0.064%, As≤0.03%, all the other are iron and inevitable impurity.
6. heat treating method according to claim 1, wherein, hollow core rod is of a size of
404.7mm * 140mm * 13500mm.
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| CN201310687454.6A CN103740918B (en) | 2013-12-13 | 2013-12-13 | For the heat treating method of the hollow core rod of Continuous mill train |
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| CN201310687454.6A CN103740918B (en) | 2013-12-13 | 2013-12-13 | For the heat treating method of the hollow core rod of Continuous mill train |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113981203A (en) * | 2021-11-11 | 2022-01-28 | 上海奥达科股份有限公司 | Device and process for heat treatment processing of core rod products |
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| CN101580893A (en) * | 2009-06-10 | 2009-11-18 | 江苏诚德钢管股份有限公司 | High-temperature rapid quenching method for seamless steel tube |
| CN102240889A (en) * | 2011-05-03 | 2011-11-16 | 天津钢管集团股份有限公司 | Manufacturing method for continuously rolling seamless steel pipe by using hollow mandril |
| CN102330024A (en) * | 2011-09-02 | 2012-01-25 | 上海大学 | Steel for tandem tube mill hollow mandrel and preparation technology thereof |
| KR20130135354A (en) * | 2011-03-18 | 2013-12-10 | 신닛테츠스미킨 카부시키카이샤 | Steel pipe quenching method |
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Patent Citations (4)
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| CN101580893A (en) * | 2009-06-10 | 2009-11-18 | 江苏诚德钢管股份有限公司 | High-temperature rapid quenching method for seamless steel tube |
| KR20130135354A (en) * | 2011-03-18 | 2013-12-10 | 신닛테츠스미킨 카부시키카이샤 | Steel pipe quenching method |
| CN102240889A (en) * | 2011-05-03 | 2011-11-16 | 天津钢管集团股份有限公司 | Manufacturing method for continuously rolling seamless steel pipe by using hollow mandril |
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Non-Patent Citations (1)
| Title |
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| 宋传宝等: ""改善30Cr2MoV钢大锻件冲击韧性及晶粒度的研究"", 《大型铸锻件》 * |
Cited By (1)
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| CN113981203A (en) * | 2021-11-11 | 2022-01-28 | 上海奥达科股份有限公司 | Device and process for heat treatment processing of core rod products |
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Effective date of registration: 20160810 Address after: 610000 Sichuan Chengdu bull market mouth Patentee after: Chengdu Panxi Steel Metallurgy Engineering Technology Co., Ltd. Address before: 610303, No. 268, solidarity South Road, Qingbaijiang District, Sichuan, Chengdu Patentee before: Pangang Group Chengdu Steel & Vanadium Co., Ltd. |