JP2009113066A - Electric resistance welded steel pipe for oil supply pipe - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electric resistance welded steel pipe for an oil supply pipe, which can be worked to a desired shape of the oil supply pipe without generating any serious defect such as crack even under a severe working condition such as a complicated shape and large elongation. <P>SOLUTION: A steel plate having a tin-zinc alloy coating layer 2 which comprises 70-99 mass% tin with the balance zinc and inevitable impurities and has a thickness per one side of 4-50 μm, formed on its surface is continuously formed into a steel strip. The electric resistance welded steel pipe 1 is manufactured by heating and welding edges of the obtained steel strip with the high frequency current. Further, reinforcement parts 5 of weld parts on inner and outer surfaces formed by the welding are removed to get a smooth condition. Thereafter, the rustproof treatment is applied so as to cover the removed part only on the outer surface side to get as the electric resistance welded steel pipe. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention is an oil supply pipe electric power supply that can be processed into a desired oil supply pipe shape without causing a serious defect such as cracking even under severe processing conditions such as a complicated shape or a high elongation rate. It relates to a sewn steel pipe.

  For example, oil supply pipes for automobiles and the like are required to have excellent corrosion resistance, workability, solderability, and the like. In particular, when rust occurs, oil leakage may occur and a dangerous state may occur, so corrosion resistance over a long period is required as an important characteristic.

  In addition, ERW steel pipes for oil supply pipes are conventionally shipped after the ERW steel pipes are formed from non-plated general steel, and then the welds on both the inner and outer surfaces formed by welding are cut off. Then, after a steel pipe is subjected to various forming processes into a predetermined shape in a parts manufacturer, a method of applying a general plating treatment and rust prevention coating to obtain an oil supply pipe has been adopted.

  However, in this case, there is a problem that parts manufacturers need to prepare dedicated plating equipment, which requires a certain factory space and enormous equipment costs. However, there is also a problem that the production cost is high.

  Moreover, as shown in Patent Document 1, it is conceivable to eliminate the plating process using a stainless steel pipe having excellent durability. However, since stainless steel is expensive, it is difficult to adopt from the viewpoint of cost. There was a point.

JP 2002-275660 A

  The present invention solves the above problems and has excellent corrosion resistance, workability, solderability, etc., and even in severe processing conditions such as a complicated shape or a large elongation rate. It can be machined into the desired oil supply pipe shape without causing serious defects such as cracks. Furthermore, no dedicated plating equipment is required at the parts manufacturer, and it can be produced at low cost. It was completed for the purpose of providing steel pipes.

  The electric-welded steel pipe for an oil supply pipe of the present invention made to solve the above-mentioned problem is composed of tin of 70 to 99% by mass of tin, the remaining zinc and unavoidable impurities on the surface, and a thickness of 4 to 50 μm per side. An ERW steel pipe manufactured by heat-welding an edge portion of a steel strip obtained by continuously forming a steel sheet having a zinc alloy plating layer with a high-frequency current, and a surplus in both the inner and outer welds formed by welding. Rust prevention treatment is performed so as to cover only the outer surface side of the cut portion.

  The rust prevention treatment is preferably thermal spray repair using a zinc-aluminum alloy wire, and this is the invention according to claim 2.

  The thickness of the sprayed film is preferably in the range of 5 to 40 μm, and this is the invention according to claim 3.

  The aluminum content of the zinc-aluminum alloy is preferably in the range of 5 to 30% by mass, and this is the invention according to claim 4.

  Furthermore, the steel sheet contains C ≦ 0.1% by mass%, Si ≦ 0.1%, 0.05% ≦ Mn ≦ 1.2%, P ≦ 0.04%, Al ≦ 0.1%, The balance is preferably Fe and inevitable impurities, and this is the invention according to claim 5.

  Further, the steel sheet is C ≦ 0.1% by mass%, Si ≦ 0.1%, 0.05% ≦ Mn ≦ 1.2%, P ≦ 0.04%, Al ≦ 0.1%, Ti, One or more of Nb is contained in an atomic equivalent of (C + N) content or more, the upper limit is 1.0% by mass, B is 0.0002 to 0.0030% by mass, and the balance is Fe. It is preferable that the impurity is an inevitable impurity, and this is the invention according to claim 6.

  In the invention according to claim 1, an electric resistance welded steel pipe comprising a steel plate having a tin-zinc alloy plating layer having a thickness of 4 to 50 μm per side and comprising 70 to 99% by mass of tin, the remaining zinc and unavoidable impurities on the surface. Therefore, excellent corrosion resistance, workability, solderability and the like can be ensured, and since plating is performed in advance, it is not necessary for a component manufacturer to prepare a dedicated plating facility. Furthermore, since the antirust treatment is applied so as to cover only the outer portion of the cut portion of the surplus in the welded portion of the inner and outer surfaces formed by welding, the plating layer on the outer surface side was scraped off. Corrosion resistance over a long period of time can be assured without corrosion or cracking from the part.

  In the invention which concerns on Claim 2, since the thermal spray repair with the wire of a zinc-aluminum alloy is performed, the corrosion resistance and crack resistance over a longer period can be ensured.

  In the invention which concerns on Claim 3, since the thickness of the sprayed film was made into the range of 5-40 micrometers, it becomes a smooth shape without the outer surface side of a welding part projecting, and it will be excellent in the handleability.

  In the invention which concerns on Claim 4, since aluminum content of the zinc-aluminum alloy was made into the range of 5-30 mass%, both corrosion resistance and workability can be satisfy | filled in a high dimension.

  In the invention according to claim 5, the steel sheet is C ≦ 0.1%, Si ≦ 0.1%, 0.05% ≦ Mn ≦ 1.2%, P ≦ 0.04%, Al ≦ 0 by mass%. 0.1% is contained and the balance is Fe and inevitable impurities, so that excellent corrosion resistance, workability, solderability and the like can be ensured.

  In the invention according to claim 6, the steel sheet is C ≦ 0.1%, Si ≦ 0.1%, 0.05% ≦ Mn ≦ 1.2%, P ≦ 0.04%, Al ≦ 0 by mass%. .1%, containing at least one of Ti and Nb in an atomic equivalent of (C + N) content, upper limit of 1.0% by mass, and further B from 0.0002 to 0.0030% by mass And the balance is Fe and inevitable impurities, so that excellent corrosion resistance, workability, solderability and the like can be ensured.

Hereinafter, preferred embodiments of the present invention will be described.
In the present invention, heat treatment such as hot rolling, pickling, cold rolling, etc. from the slab, an annealed steel plate subjected to rolling or the like, or a rolled material is used as a non-plating material, and pretreatment such as removal of rolling oil Then, a plated steel sheet produced by tin-zinc plating is used to form an electric resistance welded steel pipe for an oil supply pipe.

Regarding steel plate components, it is necessary to provide a rust-proof steel plate for oil supply pipes that does not contain Pb (excluding inevitable impurities), to be a component system that can be processed into a complicated shape of the oil supply pipe, and an alloy at the plating layer interface. Since the thickness of the component layer can be reduced as much as possible to prevent plating peeling and the component system needs to suppress the progress of corrosion in the internal environment and the external environment of the oil supply pipe, it is composed of the following components.
A certain amount of C is necessary from the viewpoint of securing strength. However, although the present plating bath component is an element that decreases workability and corrosion resistance, it acts as an element that suppresses the steel-plating layer interface reaction, and is advantageous in securing plating adhesion during processing. In consideration of the above, the C content is set to C ≦ 0.1% by mass%.

  Si stabilizes the steel surface oxide film, so this plating bath component tends to remain when immersed in the plating bath, hinders the plating reaction, and tends to generate a large amount of pinholes (non-plated portions) that affect corrosion resistance. . Moreover, although a certain amount of content is required from the point of ensuring strength, since it is a strength strengthening element, it is necessary to adjust the content. In addition, since the present plating bath component functions as an element that suppresses the steel-plating layer interface reaction, it is advantageous in terms of ensuring plating adhesion during processing. Considering the above, the Si content is set to Si ≦ 0.1% in mass%.

  Mn needs a certain amount of content from the viewpoint of securing strength, but because it is a strength-enhancing element, it tends to reduce workability and needs to be limited. Further, the present plating bath tends to improve the reactivity, and also promotes the steel-plating layer interface reaction, and the content needs to be adjusted to adjust the interface reaction. Considering the above, the Mn content is 0.05% ≦ Mn ≦ 1.2% in mass%.

  P has an effect of suppressing the reaction in the present plating bath and is a component necessary for suppressing the steel-plated layer interface reaction. If the content is too large, a large amount of pinholes are generated. Therefore, considering the above, P ≦ 0.04% in mass%.

  Al has an effect of suppressing the reaction in the present plating bath and is a component necessary for suppressing the steel-plated layer interface reaction. However, if the amount is too large, pinability is greatly reduced, so that pinholes are likely to occur, and the upper limit of the content must be limited. Therefore, the upper limit is set to 0.1% by mass.

  Nb and Ti are elements necessary for fixing C and N and imparting workability to the steel sheet, and can contain C and N by containing at least an atomic equivalent of (C + N). On the other hand, if the content exceeds 1.0%, the effect is saturated and the present plating bath tends to promote the steel-plating layer interface reaction, and the content needs to be adjusted in order to adjust the interface reaction. Considering the above, regarding Ti and Nb, at least one of Ti and Nb is contained in an atomic equivalent of (C + N) content, and the upper limit is 1.0% by mass.

  B is necessary for precipitation at the crystal grain boundary to increase the strength of the grain boundary, to prevent secondary work cracking and to improve workability. If the amount is too large, the effect is saturated, the hot strength becomes too high, and the hot rolling property is lowered, which is not preferable. Therefore, the content is set to 0.0002 to 0.0030% by mass.

The above-described steel sheet is plated, and a tin-zinc alloy plating layer having a thickness of 4 to 50 μm per side is formed of 70 to 99% by mass of tin, the remainder zinc and unavoidable impurities. .
In addition, as a plating method, a general method such as hot dipping or electroplating can be used. Thus, by finishing the plating process at the time of shipment of the steel plate, a dedicated plating facility is used by the component manufacturer. Can be unnecessary to prepare.

The tin-zinc alloy plating layer is composed of 70 to 99% by mass of tin, the remainder zinc and unavoidable impurities because of the corrosion resistance of fuel pipes to fuels such as gasoline and the salt damage environment that occurs when snow melting salt is applied This is because it is necessary to ensure the corrosion resistance against the above, further ensure the workability that can be processed according to the structure of the lower part of the automobile, and ensure the solderability necessary for joining the components such as the fuel pipe.
When the tin content in the plating layer is less than 70%, the corrosion resistance of the inner surface of the oil supply pipe is greatly reduced, the dissolution rate of the plating layer is increased, and the dissolution rate of the plating layer in a salt damage environment is also increased. This is because the performance is greatly reduced. Further, the remaining zinc and inevitable impurities increase, so that the workability of the plating layer is lowered and the solderability tends to be greatly lowered. On the other hand, if the tin content of the plating layer exceeds 99%, the performance is not particularly deteriorated, but the sacrificial rust prevention effect due to the plating layer in a salt damage environment is reduced. Cheap. Accordingly, the plating layer structure was composed of 70% to 99% of tin by mass%, the remaining zinc and unavoidable impurities.

  The thickness of the plating layer affects the corrosion resistance, but if it is too thin, corrosion tends to progress to the substrate in a relatively short period of time for long-term use as a fuel supply pipe material, and it covers fine pinholes generated during plating. Since it is exposed, the base corrosion occurs earlier than the life estimated from the plating thickness, and the solderability is also lowered. On the other hand, if the plating thickness is too thick, the corrosion resistance is sufficiently secured, but the performance becomes excessive. Therefore, the plating thickness was 4 to 50 μm per side.

  A steel strip having a predetermined width is continuously formed from the steel plate as described above, and an edge portion of the obtained steel strip is heated and welded with a high-frequency current to produce an ERW steel pipe. In the electric resistance welded steel pipe obtained in this way, there are surpluses formed by welding at the welded portions on both the inner and outer surfaces. This extra portion inhibits the smooth flow of gasoline on the inner surface, and also accumulates dust and the like to cause corrosion. Yes, it is cut out by cutting or the like to make it smooth.

Thereafter, a rust prevention treatment is performed so as to cover only the outer portion of the cut portion. This is because the plating layer on the surface is scraped off by cutting off the surplus portion, and thus the rust prevention treatment is performed for the purpose of preventing corrosion of the portion.
However, according to the knowledge of the present inventor, as shown in FIG. 1, since the cut portion on the inner surface side is always in contact with gasoline, the possibility of rusting is extremely low, and no rust prevention treatment is required, only the outer surface side. It was found that rust prevention treatment should be applied so as to cover the excised part of the slab. In FIG. 1, 1 is an electric resistance steel pipe having a tin-zinc alloy plating layer 2 on the surface, 3 is a welded portion, 4 is a rust preventive coating, and 5 is a surplus portion.

As the rust-proofing treatment, it is possible to apply rust-proof paint or thermal spraying of an alloy or the like.
The anticorrosion paint may be either an inorganic film or an organic film (for example, an organic resin film). As the inorganic coating, an oxide coating containing a predetermined amount of a metal element such as Zn, P, Mn, Ni, Mg, Fe, Co, and Al can be used. Since it is inorganic, if the inorganic material is the main component, the organic lubricant may be contained secondarily in the inorganic coating for lubrication.
As the organic coating, any type of organic resin such as thermosetting type, thermoplastic type, and radiation curable type can be used. Specific examples of the organic resin include acrylic, urethane, polyester, and epoxy. Furthermore, those obtained by crosslinking these resins with an appropriate curing agent can also be used. Examples of the curing agent include amino resins and epoxy resins.
Specific examples include a paint obtained by thermally curing an acrylic resin mainly composed of acrylic acid or methacrylic acid with melamine modified with methyl alcohol or butyl alcohol.

Moreover, thermal spray repair with a zinc-aluminum alloy wire can also be performed as a rust prevention treatment. In this case, the tin-zinc alloy plating layer formed on the surface of the steel plate is well-suited, and cracks can be prevented from being generated in the subsequent press working and can be sufficiently processed.
In this case, the thickness of the sprayed film is preferably in the range of 5 to 40 μm. If the thickness is less than 5 μm, it is difficult to ensure sufficient corrosion resistance, and if it is thicker than 40 μm, the workability becomes insufficient.
Moreover, it is preferable that the aluminum content of a zinc-aluminum alloy exists in the range of 5-30 mass%. This is because if it is less than 5% by mass, the workability becomes insufficient, and if it exceeds 30% by mass, it is difficult to ensure sufficient corrosion resistance.

A steel plate having the composition shown in [Table 1] was subjected to a tin-zinc plating treatment to form a plated steel plate having a tin-zinc alloy plating layer on the surface, and this steel plate was continuously formed into a steel strip having a predetermined width. The edge part of the obtained steel strip was heat-welded with a high-frequency current to produce an electric-welded steel pipe for an oil supply pipe. The dimensions and plating thickness of the electric resistance welded steel pipe are as shown in [Table 2]. Next, the surplus portions of the welded portions on both the inner and outer surfaces formed by welding were cut out to obtain a smooth state. Then, thermal spray repair with a zinc-aluminum alloy wire was performed so as to cover only the outer surface side of the cut portion. The thickness of the sprayed part is as shown in [Table 2].
Based on the combined cycle corrosion test (CCT: JASO M609-91), one cycle consists of salt spray 2 hours (5% NaCl water, 35 ° C.), drying 4 hours (60 ° C., relative humidity 30%), wet 2 hours (50 As a result of investigating the presence or absence of rust generation after 90 cycles, the occurrence of rust was not observed in both the welded part and the base material part of the steel pipe in any of the examples. The effect was confirmed.

It is an expanded sectional view of the principal part which shows embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Steel pipe main body 2 Tin-zinc alloy plating layer 3 Welding part 4 Rust prevention film 5 Extra part

Claims (6)

  An edge portion of a steel strip obtained by continuously forming a steel plate having a tin-zinc alloy plating layer having a thickness of 4 to 50 μm on one side and comprising 70 to 99% by mass of tin, the remaining zinc and unavoidable impurities on the surface. , An electric resistance welded steel pipe manufactured by heat welding with a high-frequency current, and rust-proofing so as to cover only the outer portion of the cut portion of the surplus portion of the welded portion of the inner and outer surfaces formed by welding An electric resistance welded steel pipe for an oil supply pipe.   2. The electric resistance welded steel pipe for an oil supply pipe according to claim 1, wherein the rust prevention treatment is a thermal spray repair using a zinc-aluminum alloy wire.   The thickness of the thermal spray film is in the range of 5 to 40 µm, and the electric resistance welded steel pipe for oil supply pipes according to claim 2.   The aluminum content of the zinc-aluminum alloy is in the range of 5 to 30% by mass, and the balance is zinc.   Steel sheet contains C ≦ 0.1% by mass%, Si ≦ 0.1%, 0.05% ≦ Mn ≦ 1.2%, P ≦ 0.04%, Al ≦ 0.1%, the balance The electric-welded steel pipe for an oil supply pipe according to claim 1, wherein Fe and unavoidable impurities are used.   Steel sheet is C ≦ 0.1% by mass%, Si ≦ 0.1%, 0.05% ≦ Mn ≦ 1.2%, P ≦ 0.04%, Al ≦ 0.1%, Ti, Nb At least one atomic equivalent of (C + N) content, and the upper limit is 1.0% by mass%, further B is 0.0002 to 0.0030% by mass%, and the balance is Fe and The electric-welded steel pipe for an oil supply pipe according to claim 1, wherein the inevitable impurity is an unavoidable impurity.

Images