CN1043276A - Manufacture method at former machining state high-frequency bent tubes having low hardness - Google Patents
Manufacture method at former machining state high-frequency bent tubes having low hardness Download PDFInfo
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- CN1043276A CN1043276A CN 88108495 CN88108495A CN1043276A CN 1043276 A CN1043276 A CN 1043276A CN 88108495 CN88108495 CN 88108495 CN 88108495 A CN88108495 A CN 88108495A CN 1043276 A CN1043276 A CN 1043276A
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Abstract
The present invention relates under former machining state, make the method for soft high frequency pipe bending, being that the carbon steel of external diameter of pipe below 3 times is made in the method for high frequency pipe bending with radius-of-curvature, it is characterized in that being pipe: C0.05～0.30, Si0.10～0.50, Mn0.30～1.50, P≤0.03, S≤0.03, Al0.005～0.05, N≤0.015, the rest is Fe and impurity with the carbon steel that contains following composition (being % weight); Outer surface of tube blank is heated to 850～1050 ℃; Bending machining is carried out on liquid or cooling limit, waterside slowly with cooling property.
Description
The invention relates to the manufacture method of the high frequency pipe bending that the piping system of generating, chemical industry equipment uses.
In the past, be used to generate electricity, 1.0～2.0x(external diameter of pipe of chemical industry equipment) small curvature radius carbon steel bend pipe, use be the welded type coupling bend (to call coupling bend in the following text) of regulations such as the JIS B of Japanese Industrial Standards 2311,2312.The processing of coupling bend is adopted Japanese iron and steel institute to compile under the known high temperature of the 3rd edition iron and steel brief guide VI, 179 row publications expander bending machining method usually and is processed.On material, pipe and bend pipe have roughly the same character.But, because this kind shape of product is a kind ofly to have only to the bending part of 180 ℃ of angle of bend, therefore, have when when pipe arrangement is constructed, expending the Welder, simultaneously, increased the man-hour of checking the weld also incompatiblely, prolong the duration, increase problems such as executive cost.
For this reason, people wish to reduce the weld, wish that just it is the bend pipe (to call straight tube end elbow in the following text) of straight tube that a kind of bend two ends can be arranged.
Manufacture method as straight tube end elbow (エ Le Port レ ス) has a kind of clod wash method, yet, obtain the straight tube end elbow of small curvature radius, owing in the section form tolerance of dimension of curved part, do not satisfy the size tolerance requirements of flat partially rate, therefore, this method is inapplicable.
Another kind method is open special permission communique clear 53-135870 number, clear 53-135871 number disclosed high frequency bending machining method.Adopt this method, when radius-of-curvature exceeds 3 * (external diameter of pipe), can dwindle heating bending machining zone by forced air-cooling, reaching does not have the processing of buckling.Therefore, can the not bend material problem at position.But, during 1.0～3.0 * (external diameter of pipe) the small curvature radius that obtain that people wish, for preventing to buckle, also must be by forcing cooling so that dwindle the thermal flexure process zone.For this reason, the extexine at bending machining position (accelerate down to the surface, and the sclerosis of bending machining position extexine has just become unavoidable problem by 1～2mm) speed of cooling.Usually, when the welding of the pipe arrangement of carbon steel steel pipe, consider that being suitable for practical highest hardness should be below Hv248, but in the mentioned component scope, can't satisfy this hardness regulation under high frequency bending machining state from anti-destructive security.One of effective ways that address this problem are softening annealing.But because the shape of straight tube end elbow needs large-scale annealing furnace, it is low therefore to have produced productivity, problems such as cost height.In addition, a kind of method is that the application number of former application such as the applicant is to propose in clear 62-7862 number, that is: be pipe with the carbon steel that satisfies C+Mn/6≤0.33% in the carbon steel, the outside surface of pipe is heated to 850～950 ℃, then, bending machining is carried out on water-cooled limit, limit, thereby obtains the method for the soft bend pipe under the high frequency bending machining state.But in this method, when the pipe wall thickness was excessive, even the hull-skin temperature of pipe is heated to 950 ℃ of the upper limits, the internal surface temperature of pipe was also low, and tissue is unstable after the bending machining.As desire to make tissue stable, then the temperature of outside surface will surpass 950 ℃, has so just increased the hardness of the outside surface of pipe after the bending machining.Because these shortcomings are difficult to obtain the thick tube wall straight tube of fine end elbow.
That is to say, the objective of the invention is to overcome the prior art shortcoming, the steel pipe that provides a kind of utilization to have ASTM A 106B level mechanical property, by the high frequency bending machining make small curvature radius and under former machining state the cheap straight tube end elbow of hardness below Hv248.
The inventor etc. have investigated high frequency bending machining condition to improving the influence of outer surface layer hardness.The result as shown in Figure 1, speed of cooling and the highest hardness after the bending machining when recognizing bending machining are closely related.
In addition, the inventor etc. have also investigated various compositions to improving the influence and the high frequency bending machining condition effect of outer surface layer hardness, the result also recognizes, when the hull-skin temperature of former pipe reaches Heating temperature more than 950 ℃, below 1050 ℃, steel pipe of the present invention as shown in Figure 2, by formula C+Mn/6 or formula C+Mn/6+(Cr+Mo+V)/5+(Ni+Cu)/15(to be to call the C equivalent in the following text) resulting C equivalent also with bending machining after highest hardness closely related.
The present invention finishes on the basis of above-mentioned opinion.That is to say that its purport is:
(1) in the manufacture method of machining state high-frequency bent tubes having low hardness, the feature of this manufacture method is: in radius-of-curvature is in the manufacture method of the high frequency pipe bending of external diameter of pipe below 3 times, to be by weight:
C 0.05～0.30%
Si 0.10～0.50%
Mn 0.30～1.50%
P ≤0.03%
S ≤0.03%
Al 0.005～0.05%
N ≤0.015%
Rest part is that the carbon steel that Fe and impurity constitute is pipe, and outer surface of tube blank is heated to 850～1050 ℃, carries out bending machining while cooling off with slow cool down liquid again.
(2) in the manufacture method of former machining state high-frequency bent tubes having low hardness, it is characterized in that: in radius-of-curvature is in the manufacture method of the high frequency pipe bending of external diameter of pipe below 3 times, to be by weight:
C 0.05～0.30%
Si 0.10～0.50%
Mn 0.30～1.50%
P≤0.03%
S≤0.03%
Al 0.005～0.05%
N≤0.015%
Rest part is Fe and can not keeps away impurity and constitute that the carbon steel that satisfies C+Mn/6≤0.38% is pipe, and the outside surface of pipe is heated to 850 ℃～1050 ℃, and bending machining is carried out on water-cooled limit in limit again.
(3) manufacture method of former processing soft high frequency pipe bending.It is characterized in that: in radius-of-curvature is in the manufacture method of the high frequency pipe bending of external diameter of pipe below 3 times, to be by weight:
C 0.05～0.30%
Si 0.10～0.50%
Mn 0.30～1.50%
P ≤ 0.03%
S ≤ 0.03%
Al 0.005～0.05%
N ≤ 0.015%
Have following column element in addition:
Cr ≤ 0.50%
Ni ≤0.50%
Mo ≤0.50%
V ≤0.10%
Ti ≤0.05%
Nb ≤0.05%
B ≤0.003%
Cu ≤0.50%
Zr ≤0.05%
Ca ≤0.005%
In one or two or more kinds, rest part is Fe and can not keeps away impurity and constitute, satisfies
C+Mn/6+（Cr+Mo+V）/5+（Ni+Cu）/15≤0.38%
Carbon steel tubing be pipe, outer surface of tube blank is heated to 850～1050 ℃, bending machining is carried out on water-cooled limit in limit again.
Be advisable with weldless steel tube as the employed carbon steel steel pipe of the pipe of bend pipe in the present invention in addition.But also can use electric welding seam steel pipe, UO steel pipe etc.
Fig. 3 is an example of the swan neck system of enforcement bending machining method use of the present invention.1 for treating the steel pipe of crooked processing, 2 deflector rolls of using for this steel pipe support guide, 3 is above-mentioned steel pipe 1 is spent heating in a narrow margin and is made of the high-frequency inductor that has cooling tank from the periphery part ring-type heating unit, 4 the bend arms that rotate freely for front end strap clamp pincers 5,6 is that pipe end brace table, arrow 7 are the cooling fluid from spraying with heating unit 3, and oblique line part 8 is the heating process zone.Use this device, earlier steel pipe 1 is clamped on clamp 5, when carrying out localized hyperthermia's heating, advance along the direction of arrow, finish bending machining steel pipe 1 with suitable means by 3 pairs of steel pipes of heating unit 1.
Below the qualifications among the present invention is illustrated.At first, be the bending machining condition, usually, in the bending machining condition, when using the high frequency heating coil heating,, therefore, use narrow coil as far as possible owing to will dwindle the heating process zone.Based on this reason, be very difficult with the whole homogeneous heating of tube wall, and internal surface temperature is lower than outside surface relatively.For making tissue stable, when thickness of pipe deficiency 12.5mm, the Heating temperature scope of outside surface is advisable with 850～950 ℃.If thickness of pipe is between 12.5mm～50.4mm the time, stable for making tissue, the Heating temperature scope of outside surface is advisable with 950～1050 ℃.That is to say, make minimum Heating temperature that the Heating temperature of internal surface is brought up to Ac
3More than.
When making the little high frequency pipe bending of radius-of-curvature,, need make it bear sufficient axial compressive force by force in order to reduce the bend thickness of pipe that is subjected to stretch process.At this moment, if heating processing district field width, then bending machining begins the inboard wrinkle that produce in back, causes longitudinal bending, so that can't process.
For this reason, if the air cooled words of the such pressure of similar normalizing are adopted in the cooling that adds after the hot-work,, can't produce the slick bend pipe of shape though can avoid the raising of hardness.
So, in order to dwindle the width of heating process zone, consider from shape, hardness aspect, with the method controlled chilling speed of spraying slow cool down liquid, thereby address the above problem.
That is to say, the speed of cooling of outer surface of tube blank be 5 ℃/when carrying out bending machining below the S, the inboard wrinkle that easily produce.If during near the higher limit of this composition series, be accompanied by the quickening of speed of cooling, hardness rises, therefore, speed of cooling with 50 ℃/be advisable below the S.
In addition, slow cool down liquid used in the present invention has: the PVA(polyvinyl alcohol), PVP(polyvinylpyrrolidone), the PGA(polyalkylene glycol), the PEG(polyoxyethylene glycol) etc. water-soluble polymers.Also have mineral oil, vegetables oil, animal wet goods lipid or hot water also to have same effect.
Below, the composition of pipe used herein limited be illustrated.
C is for guaranteeing the necessary element of steel strength, and bring into play its function usage quantity should be more than 0.05%.But, if carbon content surpasses 0.30%, then not only can the apparent damage weldprocedure, the hardness after the bending machining is significantly increased.Therefore, carbon content on be limited to 0.30%.
Si also is a kind of effective element that can guarantee hot strength except doing the deoxidant element use.Bring into play its deoxygenation function, need more than 0.10% at least.But content is too much, can damage high frequency bending machining performance, and therefore, its SC service ceiling is 0.50%.
Mn is the efficient hardening element that is only second to C, bring into play its function, and used in amounts is wanted more than 0.30%.But excessive interpolation can be increased the maximum intensity after the bending machining, also can damage weldprocedure, therefore, with its ceiling restriction 1.50%.
P, S are the elements of sneaking into as impurity.In order to prevent that hot bending from adding crackle takes place man-hour, their upper limit all is limited in below 0.03%.
Al is the effective element that uses as the grain refining element.Because the interpolation of this element makes us can improve the upper limit content of C, Si and Mn.For bringing into play its this function, content must be more than 0.005%.If excessive use then can damage the toughness of steel pipe, therefore, SC service ceiling is 0.050%.
The content of N is the upper limit not producing welding property in the scope of obstacle with 0.015%.
Except above essentially consist, also should satisfy: C+Mn/6≤0.38% or
C+Mn/6+（Cr+Mo+V）/5+（Ni+Cu）/15≤0.38%
Condition.At this moment, though do not use slow cool down liquid can reach the cooling performance of expection yet, but still be advisable to spray water-cooled.That is to say that in order to dwindle the heating process zone as far as possible, replacement adds the forced air-cooling after the hot-work, adopt to have the injection water-cooled of good cooling performance.The resistance to deformation in water-cooled zone is increased substantially, to solve the problem that to process owing to longitudinal bending than the resistance to deformation of heating process zone.This water-cooled is slower more in the past than the speed of cooling of Forced water cooling that with the quenching was purpose.
Owing to recognize that in the condition of above-mentioned high frequency bending machining the highest hardness of outside surface and C equivalent are closely related after the bending machining, therefore, for making the outside surface highest hardness below Hv248, the normal ceiling restriction of C is below 0.38%.
At this moment, though V has crystal grain thinning and strengthening effect, it is just not obvious to surpass 0.10% o'clock effect, therefore, is limited to 0.10% on it.
Cr, Mo, Ni, Cu, very effective as strengthening element.But any consumption too much all can cause the hardness after the bending machining to improve.Therefore, the upper limit of every kind of element all is limited in 0.50%.
Nb, Ti, Zr are the elements with grain refining effect, and it is the upper limit that its addition separately no longer significantly measures 0.05% with its effect.
Ca can work to improving toughness by the form of control sulfide.But therefore excessive interpolation meeting deterioration welding property, is limited to 0.005% on it.
The trace of B adds the effect with raising steel strength.But it is just no longer obvious that addition surpasses 0.003% effect.Therefore, be limited to 0.003% on it.
With embodiment and comparative material contrast, the feature of steel pipe of the present invention is described below.
Embodiment 1
Be to adopt 3 kinds of steel pipes in the table 1, according to the condition changing speed of cooling that is applied, carrying out radius-of-curvature is the high frequency bending machining of 2D.
Speed of cooling is thermopair to be melted be attached to steel tube surface, the temperature measuring between 800～400 ℃.
Very clear and definite in the middle of these examples, speed of cooling surpass 50 ℃/s (G), highest hardness can not be for actual use more than Hv248 for C, F.
In contrast (D, E, H, I, J etc.) since speed of cooling 50 ℃ of the present invention regulation/below the s, therefore, can produce and satisfy the high frequency pipe bending of highest hardness below Hv248.
Embodiment 2
Being shown in the table 2 for the chemical ingredients of bending machining with steel pipe.The steel pipe of A1～A9 is that the C equivalent is at the rolling carbon steel steel pipe more than 0.38% for comparing steel pipe.The steel pipe of B1-B11 is a steel pipe of the present invention, is that the C equivalent is at the wroughtsteel pipe below 0.38%.
Table 3 expression be the highest hardness of crooked position after mechanical property, bending machining condition and the bending machining of steel pipe pipe in the table 2.
Mechanical property is tensile strength, the unit elongation of measuring with the JIS12 test film.
As shown in table 3, all maximum heating temperature for test tube are 850～1050 ℃, adopt the injection water-cooled to carry out the high frequency bending machining.When carrying out bending machining under the condition that is applied, the relation of C equivalent and highest hardness as shown in Figure 2.As Fig. 2 clearly show like that, the highest hardness that the C equivalent surpasses comparison steel pipe A1～A9 of 0.38% can not be for the reality use all more than Hv248.
In contrast, owing to be used for steel pipe B1-B11 of the present invention, therefore the C equivalent, can produce and satisfy the high frequency pipe bending of highest hardness below Hv248 below 0.38%.
Utilize the present invention, can weldless steel tube or other steel pipe be pipe, make straight tube end elbow by the high frequency bending, be used for replacing the generating that in the past constituted, the small curvature radius bend pipe that chemical industry equipment is used by elbow.Have can reduce cost significantly, hardness is low, be imbued with advantages such as security.
The simple declaration of accompanying drawing
The graphic representation of the relation of speed of cooling and highest hardness Hv when Fig. 1 is expression high frequency bending machining.
Fig. 2 is the graphic representation of the relation of highest hardness Hv after expression C equivalent and the bending machining, and bending machining condition at this moment is: outside surface maximum heating temperature is 850～1050 ℃, the injection water cooling.
Fig. 3 is the orthographic plan of the bending machine of embodiment of the invention use.
1 ... steel pipe 2 ... deflector roll
3 ... heating unit 4 ... bend arm
5 ... clamp 6 ... the pipe end brace table
7 ... shower cooling liquid 8 ... the heating process zone
Claims (3)
1, a kind of manufacture method at former machining state high-frequency bent tubes having low hardness is characterized in that: be that the carbon steel tubing of external diameter of pipe below 3 times made in the manufacture method of high frequency pipe bending, to be with radius-of-curvature by weight:
C 0.05～0.30%
Si 0.10～0.50%
Mn 0.30～1.50%
P≤ 0.03%
S≤ 0.03%
Al 0.005～0.05%
N≤ 0.015%
Rest part is that the carbon steel tubing that Fe and impurity constitute is a pipe, with outer surface of tube blank ratio-frequency heating to 850～1050 ℃, carries out bending machining while cooling off with slow cool down liquid again.
2, a kind of manufacture method at former machining state high-frequency bent tubes having low hardness is characterized in that: in radius-of-curvature is in the manufacture method of the high frequency pipe bending of external diameter of pipe below 3 times, to be by weight:
C 0.05～0.30%
Si 0.10～0.50%
Mn 0.30～1.50%
P ≤ 0.03%
S ≤ 0.03%
Al 0.005～0.05%
N ≤ 0.015%
Rest part is Fe and can not keeps away impurity and constitute that the carbon steel that satisfies C+Mn/6≤0.38% is pipe, and with outer surface of tube blank ratio-frequency heating to 850～1050 ℃, bending machining is carried out on water-cooled limit in limit again.
3, a kind of manufacture method at former machining state high-frequency bent tubes having low hardness is characterized in that: in radius-of-curvature is in the manufacture method of the high frequency pipe bending of external diameter of pipe below 3 times, to be by weight:
C 0.05～0.30%
Si 0.10～0.50%
Mn 0.30～1.50%
P ≤ 0.03%
S ≤ 0.03%
Al 0.005～0.05%
N ≤ 0.015%
Have following column element in addition:
Cr≤ 0.50%
Ni≤ 0.50%
Mo≤ 0.50%
V≤ 0.10%
Ti≤ 0.05%
Nb≤ 0.05%
B≤ 0.003%
Cu≤ 0.50%
Zr≤ 0.05%
Ca≤ 0.005%
In one or two or more kinds, rest part is Fe and can not keeps away impurity and constitute.Satisfy
C+Mn/6+(Cr+Mo+V)/5+(Ni+Cu) carbon steel/15≤0.38% is pipe, and with outer surface of tube blank ratio-frequency heating to 850～1050 ℃, bending machining is carried out on water-cooled limit in limit again.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 88108495 CN1020260C (en) | 1988-12-10 | 1988-12-10 | Process for producing high-frequency bent tubes having low hardness as worked |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 88108495 CN1020260C (en) | 1988-12-10 | 1988-12-10 | Process for producing high-frequency bent tubes having low hardness as worked |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1043276A true CN1043276A (en) | 1990-06-27 |
| CN1020260C CN1020260C (en) | 1993-04-14 |
Family
ID=4835088
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 88108495 Expired - Fee Related CN1020260C (en) | 1988-12-10 | 1988-12-10 | Process for producing high-frequency bent tubes having low hardness as worked |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN1020260C (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101450356B (en) * | 2007-12-04 | 2010-06-02 | 中国石油天然气集团公司 | Manufacture method of high-intensity hot bend pipe |
| CN101132938B (en) * | 2005-03-02 | 2010-12-15 | 住友金属工业株式会社 | Member for reinforcing vehicle body |
-
1988
- 1988-12-10 CN CN 88108495 patent/CN1020260C/en not_active Expired - Fee Related
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101132938B (en) * | 2005-03-02 | 2010-12-15 | 住友金属工业株式会社 | Member for reinforcing vehicle body |
| CN101450356B (en) * | 2007-12-04 | 2010-06-02 | 中国石油天然气集团公司 | Manufacture method of high-intensity hot bend pipe |
Also Published As
| Publication number | Publication date |
|---|---|
| CN1020260C (en) | 1993-04-14 |
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