CN104073719A - High-strength welded steel pipe and manufacturing method thereof - Google Patents
High-strength welded steel pipe and manufacturing method thereof Download PDFInfo
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Abstract
The invention discloses a high-strength welded steel pipe. The high-strength welded steel pipe is characterized by comprising the following chemical elements in percentage by mass: 0.11-0.18% of C, 0.15-0.35% of Si, 0.8-1.6% of Mn, 0.005-0.05% of V, 0.002-0.04% of Al, 0.005-0.05% of Ti, 0.005-0.05% of Nb, 0.05-0.20% of Mo and balance of Fe and other inevitable impurities. The invention also discloses a manufacturing method of the high-strength welded steel pipe. The manufacturing method of the high-strength welded steel pipe sequentially comprises the following steps: smelting, casting, rolling, laminar flow cooling, coiling, welding and moulding, cooling by virtue of water spray, and heat treatment of welding lines. The high-strength welded steel pipe has good welding performance and high yield strength, and the welded steel pipe has isotropy; besides, welding lines and base of the steel pipe have high-strength toughness with the same strength.
Description
Technical field
The present invention relates to a kind of metallurgic product and manufacture method thereof, relate in particular to a kind of Welded Steel Pipe and manufacture method thereof.
Background technology
Soft steel and low alloy steel that the construction(al)steel life-time service yield strength of China is 235-345MPa.The yield strength grade of the low alloy steel of being announced by < < Code for design of steel structures > > GB50017-2003 at present, has risen to 460MPa.Adopt the steel pipe for building of high strength grade, object is for attenuate steel construction cross dimensions and saves and build input cost.By the steel pipe of high strength grade, as steel pipe for building, this type of steel pipe often will bear very large shock load when piling, and when static load, may need to bear destructive force seismic wave longitudinally greatly.
The distinguishing features such as than weldless steel tube, it is high that welded tube has production efficiency, and dimensional precision is good, and specification limit is wide, cost is low, therefore, Welded Steel Pipe is also usually applied in construction steel structure.But the welding process of welded tube also can have a negative impact to the mechanical property of steel matrix.High frequency resistance welding ERW (Electric Resistance Welding) is a kind of surface action by high-frequency current (Skin Effect) and approach effect (Proximity Effect), utilize high-frequency current or the resistance heat of the high-frequency current of inducting docks edges of boards, edge heating fusing, and impose extruding and the welding process of seam.The heat fused process of edges of boards is accompanied by oxidation and decarburization phenomenon, causes the microtexture and the matrix that weld welded bonds and heat affected zone thereof to exist difference; Thereby the yield strength of commissure than the low 50-100MPa of the yield strength of mother metal left and right, causes the circumferential strength skewness of welded casing conventionally, thereby seriously reduced the withstand shocks ability of load of Welded Steel Pipe.
The production technique of high frequency resistance welding sleeve pipe (ERW sleeve pipe) comprises step: steel-smelting continuous casting-be rolled into coiled sheet-coiled sheet is sheared butt welding-strip moulding-in the thermal treatment of wire bonding-weld seam or the processing-factory inspection of homogeneous tube thermal treatment-pipe etc. end to end.It is to realize multireel to produce continuously that coiled sheet is sheared butt welding operation end to end, and embodies the critical process of ERW sleeve pipe production efficiency.But due to coiled sheet end to end butt welding the carbon equivalent of material has been proposed to corresponding requirement, otherwise easily cause the broken belt of steel plate and have a strong impact on production efficiency.
Publication number is JPS56-035749A, and open day is on April 8th, 1981, and the Japanese documentation that name is called " the welded tube steel band with high tensile performance " has related to a kind of manufacture method of ERW sleeve pipe.In this ERW sleeve pipe composition, not containing reinforced alloys elements such as Ti, Nb, V, Cr, although the ERW sleeve pipe obtaining by this manufacture method can meet high-intensity requirement, the Si content in this ERW sleeve pipe is up to 1wt.%, and carbon equivalent is up to 0.8.
Publication No. is JPS59-047364A, and date of publication is on March 17th, 1984, and the Japanese documentation that name is called " the etch-proof welded steel pipes steel of a kind of shape of resistance to ditch " discloses a kind of welded steel pipes steel.The chemical element quality percentage composition of this steel is that the composition of (wt.%) forms: C :≤0.20, Si :≤0.5, Mn :≤1.5, P≤0.03, S≤0.0015, Al :≤0.1, Ca:0.0001-0.004, Cu:0.1-0.5, at least one REM:0.001-0.05 in following element, Mg:0.0001-0.05, Ti:0.003-0.05, Zr:0.003-0.05, Se:0.01-0.05, Te:0.003-0.05, surplus is Fe and other inevitable impurity.In steel in this Japanese documentation, added Cu, to realize the requirement of producing high strength casing, but because Cu is substantially insoluble to ferrite and separates out with the form of ε-Cu or face-centered cubic α-Cu in room temperature, make the strengthening effect of steel very large for the susceptibility of speed of cooling.
Publication No. is CN1537967A, and date of publication is on October 20th, 2004, and the Chinese patent literature that name is called " a kind of low-carbon (LC) 520MPa grade composite strengthening ultrafine grain belt steel preparation method " discloses a kind of manufacture method of complex intensifying ultrafine grain belt steel.This each chemical component weight ratio with steel is C:0.12～0.15%, Si:0.15～0.40%, Mn:1.10～1.30%, b:0.007～0.015%, P<0.01%, S<0.01%, all the other are Fe and other inevitable impurity, through smelting also continuous casting, becoming blank, is 1190～1210 ℃ by blank heating to temperature; In austenite recrystallization district, non-recrystallization district and the controlled rolling of deformation induced phase change zone, roughing start rolling temperature is 1140～1160 ℃, roughing finishing temperature is 1040～1050 ℃, workpiece thickness is 32～45mm, finish rolling start rolling temperature is 1000～980 ℃, and finish rolling finishing temperature is 790～820 ℃, carries out water-cooled between finishing stand, roll 20～30 ℃/s of rear speed of cooling, coiling temperature is 430～470 ℃.
Summary of the invention
The object of the present invention is to provide a kind of high strength welded steelpipe, the welding property of this high strength welded steelpipe is good, and yield strength is high, and this Welded Steel Pipe has isotropy.In addition, the weld seam of high strength welded steelpipe of the present invention and matrix have equicohesive high-strong toughness, can meet the requirement of the construction(al)steel of the above grade of steel of 550Mpa.
To achieve these goals, the present invention proposes a kind of high strength welded steelpipe, its chemical element quality per distribution ratio is:
Surplus is Fe and other inevitable impurity.
The principle of design of each chemical element in high strength welded steelpipe of the present invention is:
C: along with increasing of C content, the welding property of steel reduces, but will damage the intensity of steel when C content is too low.Therefore, the C content in high strength welded steelpipe of the present invention should be set as 0.11-0.18wt.%.
Si:Si can solid solution in ferrite to improve the yield strength of steel, yet its content is unsuitable too high.In technical scheme of the present invention, need Si content to be controlled between 0.15-0.35wt.% scope.
Mn:Mn is mainly dissolved in ferrite to play strengthening effect, thereby improves ferritic intensity.But, when Mn content is too high, can produce serious segregation, and produce martensite in part.In order to take into account the intensity of steel and to control macrosegregation, the Mn content in high strength welded steelpipe of the present invention need to be set as to 0.8-1.6wt.%.
The carbonitride of V:V can be separated out in ferrite, and it has stable ferrite and postpones the effect of bainitic transformation, can in controlling cooling process, improve the intensity of steel, can also improve the mechanical property of weld seam simultaneously.Therefore,, for high strength welded steelpipe of the present invention, V content need to be controlled as 0.005-0.05wt.%.
Al:Al is traditional deoxidation nitrogen killer, and it can form AlN with N.AlN can refine austenite crystal grain, is conducive to improve the toughness of steel.In technical scheme of the present invention, need the content of Al element to control as 0.002-0.04wt.%.
Ti:Ti is the forming element of strong carbonitride, and it can form TiN, TiC compound with N, C.In soaking with reheat in process, TiN and TiC all can refine austenite crystal grain, improve the mechanical property of weld seam.If Ti content is too high, easily in steel, form thick TiN, do not reach the object of interpolation.So, at high strength welded steelpipe of the present invention, Ti content should be set as to 0.005-0.05wt.%.
Nb:Nb is also the forming element of strong carbonitride, and it can postpone austenite recrystallization and reach the effect of crystal grain thinning when hot rolling.In addition, in reheating process, it can also hinder growing up of austenite crystal, improves Fracture of Material And.Technical scheme of the present invention is controlled Nb content for 0.005-0.05wt.% based on this.
Mo:Mo is the element that improves hardening capacity, and it can improve the temper resistance of steel effectively.During tempering, carbide precipitate can improve the intensity of steel, yet Mo addition is unfavorable for the welding of steel when too high.Meanwhile, steel expensive, should not add too much, easily causes the rising of production cost.Therefore, in technical scheme of the present invention, Mo content should be controlled is 0.05～0.20wt.%.
High strength welded steelpipe of the present invention adopts low carbon content on Composition Design, keeps suitable Mn content, adds the microalloy elements such as appropriate Mo, V, Ti, Nb, by the complete processing of optimizing, and obtains isotropic high strength welded steelpipe.
Further, in high strength welded steelpipe of the present invention, also comprise≤0.005% B element.
B is the element that improves alloy hardening capacity, and it can strengthen crystal boundary effectively, therefore, and the B element of can add in the present invention≤0.005wt.%.
Further, carbon equivalent Ceq≤0.5 of high strength welded steelpipe of the present invention, Ceq=C+Mn/6+ (Cr+Mo+V)/5.
Correspondingly, the present invention also provides the manufacture method of above-mentioned high strength welded steelpipe, and it comprises step successively: smelt; Casting; Rolling; Laminar flow is cooling; Batch; Welding fabrication; Water smoke is cooling; Weld seam thermal treatment.
Further, in the rolling step of the manufacture method of intensity Welded Steel Pipe of the present invention, be heated to 1200-1300 ℃ of rolling, finishing temperature is 850-930 ℃.
Further, batching in step of the manufacture method of intensity Welded Steel Pipe of the present invention, coiling temperature is 500-560 ℃.
Further, in the welding fabrication step of the manufacture method of intensity Welded Steel Pipe of the present invention, welding temperature is 1300-1400 ℃.
Further, in the water smoke cooling step of the manufacture method of intensity Welded Steel Pipe of the present invention, speed of cooling is 5-30 ℃/s.
Further, in the weld seam heat treatment step of the manufacture method of intensity Welded Steel Pipe of the present invention, thermal treatment temp is 900-1000 ℃.
The manufacture method of high strength welded steelpipe of the present invention is on the basis of reasonable component design, by controlled rolling and controlled cooling and the elaboration in coiled sheet moulding process, improve the intensity of steel, to obtain, intensity is high, isotropic Welded Steel Pipe of good welding performance.
Large and the stable mechanical property of the intensity of high strength welded steelpipe of the present invention, its yield strength >=550Mpa, 0 ° of full-scale ballistic work > 80J.
Compared to Welded Steel Pipe of the prior art, because the carbon equivalent of high strength welded steelpipe of the present invention is low, it has good welding property, can meet the requirement of shearing butt welding completely.
In addition, high strength welded steelpipe alloy addition level of the present invention is low, production cost economy.
The manufacture method of high strength welded steelpipe of the present invention is by controlled rolling and controlled cooling and to coiled sheet moulding and the heat treated control of weld seam, can produce the Welded Steel Pipe of making the high and good welding performance of intensity.
In addition, the manufacture method production cost of high strength welded steelpipe of the present invention is low, good in economic efficiency.
embodiment
To high strength welded steelpipe of the present invention and manufacture method thereof be made and being further illustrated according to specific embodiment below, but specific embodiment and related description form the improper restriction for technical scheme of the present invention.
Embodiment A 1-A5 and comparative example B1-B2
According to following step, manufacture the Welded Steel Pipe in embodiment A 1-A5 and comparative example B1-B2:
1) smelt: molten steel is through converter or electrosmelting, and the quality per distribution ratio of controlling each chemical element in embodiment A 1-A5 and comparative example B1-B2 is as shown in table 1;
2) casting: slab is made in casting;
3) rolling: be heated to 1200-1300 ℃ and be rolled, finishing temperature is 850-930 ℃;
4) laminar flow is cooling: roll rear slab cooling through laminar flow;
5) batch: coiling temperature is 500-560 ℃;
6) welding fabrication: welding temperature is 1300-1400 ℃;
7) water smoke is cooling: speed of cooling is 5-30 ℃/s;
8) weld seam thermal treatment: thermal treatment temp is 900-1000 ℃.
Table 1 has been listed the quality per distribution ratio of each chemical element in this case embodiment A 1-A5 and comparative example B1-B2.
Table 1. (wt%, surplus is Fe and other inevitable impurity)
Note *: Ceq=C+Mn/6+ (Cr+Mo+V)/5
Table 2 has been listed the various process parameters of manufacturing the Welded Steel Pipe in this case embodiment A 1-A5 and comparative example B1-B2.
Table 2.
Table 3 has been listed the comprehensive mechanical property of each Welded Steel Pipe in this case embodiment A 1-A5 and comparative example B1-B2.
Table 3.
As can be seen from Table 3, the body of above-described embodiment A1-A5 and the transverse yield strength of weld seam are all more than 580Mpa, and the transverse tensile strength of body and weld seam is all more than 760Mpa, and Rp0.2 >=610Mpa, Rm >=765Mpa, 0 ℃ of full-scale ballistic work >=85J.In addition it can also be seen that, the difference of the horizontal body of the high strength welded steelpipe in embodiment A 1-A5 and the longitudinally yield strength between body is very little, and laterally the difference of the yield strength between body and transverse weld is also very little, illustrate that steel pipe seam and the body of this high-intensity welding sleeve pipe after welding has equicohesive high-strong toughness, isotropic behavior is good.Otherwise, because the chemical element composition of comparative example B1 is comparatively simple, do not contain the elements such as Mo, V and Ti, its yield strength is far below 550MPa grade of steel, and the difference of the yield strength between its horizontal body and the longitudinally yield strength between body and laterally body and transverse weld differs larger, can not meet isotropic requirement of welded casing; C content in comparative example B2 is higher, and the impelling strength of steel can decline significantly, can not meet the harsh requirement for the shock load of high strength welded steelpipe.
Be noted that above enumerate only for specific embodiments of the invention, obviously the invention is not restricted to above embodiment, have many similar variations thereupon.If all distortion that those skilled in the art directly derives or associates from content disclosed by the invention, all should belong to protection scope of the present invention.
Claims (9)
1. a high strength welded steelpipe, is characterized in that, its chemical element quality per distribution ratio is:
C：0.11～0.18％；
Si：0.15～0.35％；
Mn：0.8～1.6％；
V：0.005～0.05％；
Al：0.002～0.04％；
Ti：0.005～0.05％；
Nb：0.005～0.05％；
Mo：0.05～0.20％；
Surplus is Fe and other inevitable impurity.
2. high strength welded steelpipe as claimed in claim 1, is characterized in that, also comprises≤0.005% B element.
3. high strength welded steelpipe as claimed in claim 1, is characterized in that, its carbon equivalent Ceq≤0.5, Ceq=C+Mn/6+ (Cr+Mo+V)/5.
4. the manufacture method of the high strength welded steelpipe as described in any one in claim 1-3, it comprises step successively: smelt; Casting; Rolling; Laminar flow is cooling; Batch; Welding fabrication; Water smoke is cooling; Weld seam thermal treatment.
5. the manufacture method of high strength welded steelpipe as claimed in claim 4, is characterized in that, in described rolling step, is heated to 1200-1300 ℃ of rolling, and finishing temperature is 850-930 ℃.
6. the manufacture method of high strength welded steelpipe as claimed in claim 4, is characterized in that, described, batches in step, and coiling temperature is 500-560 ℃.
7. the manufacture method of high strength welded steelpipe as claimed in claim 4, is characterized in that, in described welding fabrication step, welding temperature is 1300-1400 ℃.
8. the manufacture method of high strength welded steelpipe as claimed in claim 4, is characterized in that, in described water smoke cooling step, speed of cooling is 5-30 ℃/s.
9. the manufacture method of high strength welded steelpipe as claimed in claim 4, is characterized in that, in described weld seam heat treatment step, thermal treatment temp is 900-1000 ℃.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105458633A (en) * | 2016-01-06 | 2016-04-06 | 河北华通线缆集团股份有限公司 | Manufacturing method of low-carbon steel coiled tubing |
| CN105583573A (en) * | 2014-10-20 | 2016-05-18 | 沈阳黎明航空发动机(集团)有限责任公司 | Processing technology method of precise large-size rigid pipe assembly |
| CN110257612A (en) * | 2019-06-17 | 2019-09-20 | 首钢集团有限公司 | A kind of preparation method of low residual stress low alloy high strength steel plate |
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| CN110257612A (en) * | 2019-06-17 | 2019-09-20 | 首钢集团有限公司 | A kind of preparation method of low residual stress low alloy high strength steel plate |
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Application publication date: 20141001 |