CN103045945A - Economical fabrication method of high-toughness X70 pipeline hot rolled steel plate coil - Google Patents
Economical fabrication method of high-toughness X70 pipeline hot rolled steel plate coil Download PDFInfo
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- CN103045945A CN103045945A CN201310001802XA CN201310001802A CN103045945A CN 103045945 A CN103045945 A CN 103045945A CN 201310001802X A CN201310001802X A CN 201310001802XA CN 201310001802 A CN201310001802 A CN 201310001802A CN 103045945 A CN103045945 A CN 103045945A
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Abstract
The invention provides an economical fabrication method of a high-toughness X70 pipeline hot rolled steel plate coil, which comprises the steps of a heating procedure, a rough rolling procedure, a finish rolling procedure, a cooling procedure and a coiling procedure and is characterized in that (1) in the heating procedure: the heating temperature is 1150-1210 DEG C, and the soaking time is not shorter than 120min; (2) in the rough rolling procedure, 8-10-pass rough rolling is conducted, the deformation for each pass is required to be within 10-20%, and the deformation is 18-20% for the last 3 passes of rough rolling; (3) in the finish rolling procedure, the rolling temperature of the first pass of finish rolling is not higher than 1050 DEG C, the deformation for the last pass of finish rolling is less than 8%, the accumulated deformation of the last two passes is less than 16%, and the finishing temperature of the finish rolling is 770-850 DEG C; (4) in the cooling procedure: laminar cooling is conducted at a cooling rate of 18-26 DEG C/s after the finish rolling; and (5) in the coiling procedure, coiling is conducted at 300-400 DEG C after the laminar cooling.
Description
Technical field
The present invention relates to X70 line steel hot rolling coiled sheet and preparation method thereof.
Background technology
Produce the Composition Design that the X70 pipe line steel generally adopts ' Nb+Mo ' both at home and abroad, to obtain acicular ferrite structure; Obtain higher low-temperature impact toughness on the one hand, on the other hand, reduce Bauschinger effect, that is, and the decline of material yield strength property behind the minimizing tubulation.Find through large quantity research, in the industrial production of X70 pipe line steel, even adopt molybdenum element can obtain uniform acicular ferrite structure fully, can not avoid the generation of Bauschinger effect fully.When serious, the matrix of X70 pipe line steel coiled sheet is the mixed structure of ferrite, granular bainite and a small amount of acicular ferrite of Polygons form, and the drop-out value of yield strength makes the yield strength of X70 steel pipe be near or below lower value 485MPa near 100MPa before and after the coiled sheet tubulation.
In addition, in the manufacturing of X70 coiled sheet, adopt molybdenum element, although can suppress polygonal ferrite forms, be more convenient for obtaining acicular ferrite structure, so that manufacturing process is simple and direct feasible, still, the shortcoming of this way also clearly, that is, the molybdenum of every adding 0.10% in steel improves 220～250 yuan of ton steel production costs.
Summary of the invention
The technical problem to be solved in the present invention provides a kind of preparation method of economical high tenacity X70 line steel hot rolling coiled sheet, the tissue of the X70 line steel hot rolling coiled sheet of the present invention's preparation is that tiny needle-like voxel volume is main heterogeneous structure, make it have the high-intensity good low temperature impact properties that also has simultaneously, the enforcement of this patent, can effectively reduce Bauschinger effect to 30MPa on the one hand, can avoid on the other hand production cost too high.
For solving the problems of the technologies described above, the invention provides a kind of preparation method of economical high tenacity X70 line steel hot rolling coiled sheet, the weight percent (%) of described X70 line steel hot rolling coiled sheet chemical ingredients is: 0.060%＜C≤0.075%, 0.15%≤Si≤0.30%, 1.20%≤Mn≤1.65%, 0.070＜Nb≤0.080%, 0.010%≤Ti≤0.020%, Cr≤0.25%, all the other are iron and inevitable impurity; The preparation method of described X70 line steel hot rolling coiled sheet comprises heating, roughing, finish rolling, cooling, coiling process, it is characterized in that,
(1) heating process: 1150～1210 ℃ of Heating temperatures, soaking time is no less than 120 minutes;
(2) roughing operation: use 8～10 passage roughing, every time deflection requires between 10～20%, the deflection 18-20% of last 3 passages of roughing;
(3) finish rolling operation: finish rolling the first passage rolling temperature is not higher than 1050 ℃, and last pass deformation of finish rolling is less than 8%, and last two passage cumulative deformations are less than 16%, 770-850 ℃ of finish rolling finishing temperature;
(4) refrigerating work procedure: implement immediately the laminar flow cooling after the finish rolling, rate of cooling is greater than 15 ℃/s;
(5) coiling process: after the laminar flow cooling, coil into coiled sheet through reeling machine, 300-400 ℃ of coiling temperature scope.
Technical scheme of the present invention has following three main points: (1) adopts the low-carbon (LC) Composition Design, carries out Nb-microalloying; (2) target is to obtain evenly tiny acicular ferrite structure to improve obdurability; (3) reduce to greatest extent S, P, N content by the super clean smelting, reduce the Grain Boundary Segregation of manganese sulfide inclusion and phosphorus with further raising low-temperature impact work.
X70 line steel hot rolling coiled sheet of the present invention adopts the mode of ' controlled rolling+accelerations cooled off ' to produce, it by high temperature austenite district Deformation recrystallization, low temperature austenite non-recrystallization district distortion and roll after acceleration cool off to obtain best grain refining effect.Microstructure is controlled and crystal grain thinning, lower temperature region in austenite recrystallization district and austenite non-recrystallization district is carried out multi-pass rolling, carry out higher speed of cooling (〉=15 ℃ ℃/S) under, it is tiny uniformly take acicular ferrite as main body that deformed austenite is changed into, and the heterogeneous structure that exists a small amount of granular bainite to form.
Compared with prior art, the present invention has following technical characterstic:
(1) X70 pipe line steel of the present invention has more stable intensity and excellent low-temperature impact toughness.
(2) grain-size of X70 pipe line steel of the present invention is tiny, 12～13 grades of grain fineness numbers.
(3) microstructure of X70 pipe line steel of the present invention is acicular ferrite, has quasi-polygonal ferrite and the martensite/austenite of minute quantity.
(4) the yield strength representative value of X70 coiled sheet of the present invention is 540MPa, tensile strength representative value 660MPa, and-20 ℃ of summers are 400J(10 * 10 * 55mm) than V-type ballistic work representative value ,-60 ℃ of summers are 350J(10 * 10 * 55mm) than V-type ballistic work representative value.Behind the tubulation, the yield strength representative value of X70 pipe is 520MPa, tensile strength representative value 650MPa.-20 ℃ of Charpy impact shear area (SA%) 100% of coiled sheet and steel pipe ,-15 ℃ of DWTT are 100%.
(5) show that through the batch production practice composition that this patent is designed and technique can reduce cost and stably manufactured X70 pipe line steel coiled sheet effectively, solved simultaneously Bauschinger effect obviously and the higher problem of alloy designs cost.
Description of drawings
Fig. 1: the 9.5mm slab is rolled up 1/4 thickness place microstructure.
Fig. 2: the 14.6mm slab is rolled up 1/4 thickness place microstructure.
Embodiment
The chemical ingredients scope of pipe line steel according to the present invention, through 300 tons of converter smeltings, through ladle argon-blown, the refining of LF stove, RH vacuum-treat and continuous casting, after reheating, enter two frame R1 and R2 roughing, carry out the controlled rolling of heat engine tool through 7 frames, 2250 tandem rolling unit production lines again, roll rear employing high strength cooling technique, hot rolling thickness specification 9.5mm, 14.6mm.
The chemical ingredients of X70 pipe line steel of the present invention sees Table 1, TMCP heat engine tool controlled rolling process system and sees Table 2, and performance sees Table 3～table 5.
Being mingled with of X70 pipe line steel of the present invention, microstructure and grain fineness number see Table 6～table 7.
The chemical ingredients of table 1 X70 pipe line steel of the present invention, wt%
| Retort number | Rolling lot number | C | Si | Mn | P | S |
| 12102199 | H120810390 | 0.0741 | 0.24 | 1.22 | 0.013 | 0.0006 |
| 12102433 | H120893840 | 0.0613 | 0.26 | 1.65 | 0.0109 | 0.0010 |
| 12102584 | H120893490 | 0.0657 | 0.25 | 1.39 | 0.0129 | 0.0010 |
| 12303971 | H120851560 | 0.069 | 0.24 | 1.48 | 0.0124 | 0.0009 |
The chemical ingredients of continued 1 X70 pipe line steel of the present invention, wt%
| Retort number | Rolling lot number | Nb | Ti | N | Als | Cr |
| 12102199 | H120810390 | 0.071 | 0.018 | 0.0048 | 0.025 | 0.20 |
| 12102433 | H120893840 | 0.079 | 0.011 | 0.0040 | 0.028 | 0.19 |
| 12102584 | H120893490 | 0.073 | 0.016 | 0.0040 | 0.028 | 0.18 |
| 12303971 | H120851560 | 0.077 | 0.013 | 0.0043 | 0.028 | 0.02 |
The TMCP process system of table 2 X70 pipe line steel of the present invention
The service check result of table 3 X70 pipe line steel of the present invention
Impact property (7.5 * 10 * 55mm) (with rolling to becoming the 30o direction) of table 4 X70 volume of the present invention
Impact property (10 * 10 * 55mm) (with rolling to becoming the 30o direction) of table 5 X70 volume of the present invention
The inclusion type (rank) of table 6 X70 of the present invention
The microstructure of table 7 X70 of the present invention and grain fineness number
| Lot number | Microstructure | Prior austenite grain size (level) |
| H120810390 | Acicular ferrite+granular bainite | 13.0 |
| H120893490 | Acicular ferrite+granular bainite | 12.5 |
Claims (1)
1. the preparation method of an economical high tenacity X70 line steel hot rolling coiled sheet, the weight percent (%) of described X70 line steel hot rolling coiled sheet chemical ingredients is: 0.060%＜C≤0.075%, 0.15%≤Si≤0.30%, 1.20%≤Mn≤1.65%, 0.070＜Nb≤0.080%, 0.010%≤Ti≤0.020%, Cr≤0.20%, all the other are iron and inevitable impurity; The preparation method of described X70 line steel hot rolling coiled sheet comprises heating, roughing, finish rolling, cooling, coiling process, it is characterized in that,
(1) heating process: 1150～1210 ℃ of Heating temperatures, soaking time is no less than 120 minutes,
(2) roughing operation: use 8～10 passage roughing, every time deflection requires between 10～20%, the deflection 18-20% of last 3 passages of roughing,
(3) finish rolling operation: finish rolling the first passage rolling temperature is not higher than 1050 ℃, and last pass deformation of finish rolling is less than 8%, and last two passage cumulative deformations are less than 16%, 770-850 ℃ of finish rolling finishing temperature,
(4) refrigerating work procedure: implement immediately laminar flow cooling after the finish rolling, rate of cooling is greater than 18-26 ℃/s,
(5) coiling process: after the laminar flow cooling, coil into coiled sheet through reeling machine, coiling temperature 300-400 ℃.
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| CN201310001802.XA CN103045945B (en) | 2013-01-05 | 2013-01-05 | Economical fabrication method of high-toughness X70 pipeline hot rolled steel plate coil |
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| CN201310001802.XA CN103045945B (en) | 2013-01-05 | 2013-01-05 | Economical fabrication method of high-toughness X70 pipeline hot rolled steel plate coil |
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| CN103045945B CN103045945B (en) | 2015-02-25 |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106636888A (en) * | 2016-10-21 | 2017-05-10 | 首钢总公司 | Low-carbon equivalent and high-strength X70 pipeline steel hot-rolled plate and manufacturing method thereof |
| CN106834932A (en) * | 2016-12-05 | 2017-06-13 | 马鞍山钢铁股份有限公司 | A kind of low-carbon (LC) X80 pipe line steels coiled sheet and its manufacture method |
| CN110106444A (en) * | 2019-05-30 | 2019-08-09 | 首钢集团有限公司 | A kind of driving axle housing 700MPa grades of hot-rolled sheet coils and preparation method thereof |
| CN111270156A (en) * | 2020-03-18 | 2020-06-12 | 本钢板材股份有限公司 | Production process of hot-rolled X70 pipeline steel with thickness specification of 20.0-25.4 mm |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101525722A (en) * | 2009-04-22 | 2009-09-09 | 首钢总公司 | Excellent-toughness X70 hot-rolled sheet steel and manufacturing method therefor |
| CN102021476A (en) * | 2009-09-18 | 2011-04-20 | 鞍钢股份有限公司 | Low-cost acid-resistant pipeline steel hot-rolled coil and manufacturing method thereof |
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- 2013-01-05 CN CN201310001802.XA patent/CN103045945B/en active Active
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101525722A (en) * | 2009-04-22 | 2009-09-09 | 首钢总公司 | Excellent-toughness X70 hot-rolled sheet steel and manufacturing method therefor |
| CN102021476A (en) * | 2009-09-18 | 2011-04-20 | 鞍钢股份有限公司 | Low-cost acid-resistant pipeline steel hot-rolled coil and manufacturing method thereof |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106636888A (en) * | 2016-10-21 | 2017-05-10 | 首钢总公司 | Low-carbon equivalent and high-strength X70 pipeline steel hot-rolled plate and manufacturing method thereof |
| CN106834932A (en) * | 2016-12-05 | 2017-06-13 | 马鞍山钢铁股份有限公司 | A kind of low-carbon (LC) X80 pipe line steels coiled sheet and its manufacture method |
| CN110106444A (en) * | 2019-05-30 | 2019-08-09 | 首钢集团有限公司 | A kind of driving axle housing 700MPa grades of hot-rolled sheet coils and preparation method thereof |
| CN111270156A (en) * | 2020-03-18 | 2020-06-12 | 本钢板材股份有限公司 | Production process of hot-rolled X70 pipeline steel with thickness specification of 20.0-25.4 mm |
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