KR20010010426A - A Method of Flash Butt Welding for High Strength Steel - Google Patents

A Method of Flash Butt Welding for High Strength Steel Download PDF

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KR20010010426A
KR20010010426A KR1019990029310A KR19990029310A KR20010010426A KR 20010010426 A KR20010010426 A KR 20010010426A KR 1019990029310 A KR1019990029310 A KR 1019990029310A KR 19990029310 A KR19990029310 A KR 19990029310A KR 20010010426 A KR20010010426 A KR 20010010426A
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flash
strength steel
welding
high strength
upset
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KR100325352B1 (en
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김영섭
강문진
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신현준
재단법인 포항산업과학연구원
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K11/00—Resistance welding; Severing by resistance heating
    • B23K11/002—Resistance welding; Severing by resistance heating specially adapted for particular articles or work
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K2103/00—Materials to be soldered, welded or cut
    • B23K2103/02—Iron or ferrous alloys
    • B23K2103/04—Steel or steel alloys

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Forging (AREA)
  • Pressure Welding/Diffusion-Bonding (AREA)

Abstract

PURPOSE: A method of flash butt welding of high-strength steel is provided to improve weldability and to obtain a welding portion of excellent quality by controlling conditions of flash and upset processes. CONSTITUTION: Elements made of high-strength steel are welded by butting. The entire length removed by weldment is 12-16mm of the element. First flash time is 20-25sec. Displaced distance by secondary flash is 5-8mm. Displaced distance by upset is 3-5mm. The high-strength steel contains 0.166-0.194wt% of C, 0.45-0.55wt% of Si, 2.70-2.90wt% of Mn, less than 0.02wt% of P, less than 0.01wt% of S, 0.015-0.05wt% of Al, less than 0.007wt% of N2 and 0.04-0.05wt% of Nb.

Description

고강도강의 플래쉬 버트 용접방법{A Method of Flash Butt Welding for High Strength Steel}A method of flash butt welding for high strength steel

본 발명은 냉연 고강도강 생산라인의 코일용접이나 자동차 휠림(wheel rim)용접 등의 분야에 적용할 수 있는 플래쉬 버트 용접방법에 관한 것이다.The present invention relates to a flash butt welding method that can be applied to fields such as coil welding or wheel rim welding of a cold rolled high strength steel production line.

일반적으로 플래쉬 버트(flash butt)용접은 저항용접에 있어서 대표적인 맞대기 압접방법이다. 서로 용접하기 위한 단면을 적절한 속도로 국부적인 접촉부를 발생시킴으로서, 이 접촉부가 높은 전류밀도의 단략전류로 인하여 저항발열하게 된다. 따라서, 접촉부는 용융파단되며 아크가 발생하여 그 부근이 가열된다. 이 아크에 의하여 용융된 금속은 비산하게 된다. 이것을 플래쉬라고 하는데, 이 플래쉬가 연속적으로 발생하여 용접단면을 가열하게 된다. 이 용접단면이 균일하게 가열된 상태에서 가압하여 접합하게 되는데, 이것은 업셋(upset)과정이라고 한다.In general, flash butt welding is a typical butt welding method for resistance welding. By generating the localized contact portions at appropriate speeds in the cross sections for welding to each other, the contact portions generate resistance heat due to the high current density short-circuit current. Therefore, the contact portion is melt fractured and an arc is generated and its vicinity is heated. The molten metal is scattered by this arc. This is called a flash, and this flash is generated continuously to heat the weld cross section. The weld end face is pressurized in a uniformly heated state, which is called an upset process.

한편, 플래쉬 과정에서 형성된 산화물은 플래쉬와 함께 비산되거나, 업셋과정에서 용융금속과 함께 외부로 방출하게 된다. 그러나, 용접소재의 조성이나 용접조건에 따라서 산화물은 용접부에 잔존하게 되어 용접부를 취약하게 만든다.On the other hand, the oxide formed during the flash is scattered with the flash, or is released to the outside with the molten metal in the upset process. However, depending on the composition of the welding material and the welding conditions, the oxide remains in the welded portion, which makes the welded portion weak.

특히, 고강도강은 제강과정에서 탈산과 강도향상을 목적으로 Si, Mn, Al 등을 첨가한다. 이러한 원소들이 플래쉬 버트 용접시 산화물을 형성하여 용접부에 결함을 발생시켜 고강도강 생산라인이나 고강도강을 이용한 용접시 장애로 작용하는 문제가 있다.In particular, high strength steel is added with Si, Mn, Al for the purpose of deoxidation and strength improvement during steelmaking. These elements form an oxide during flash butt welding, causing defects in the weld zone, which causes a problem in that a high-strength steel production line or an obstacle occurs when welding using high-strength steel.

이에 본 발명자들은 상기 문제점을 해결하기 위해 연구와 실험을 거듭하고 그 결과에 근거하여 본 발명을 제안하게 된 것으로, 본 발명은 고강도강의 플래쉬 버트 용접시 플래쉬과정과 업셋과정의 조건을 적절히 제어함으로서, 용접성이 향상되고 건전한 용접부가 형성되는 용접방법을 제공하고자 하는데, 그 목적이 있다.In order to solve the above problems, the present inventors have repeatedly conducted research and experiments and propose the present invention based on the results. The present invention controls the conditions of the flash process and the upset process when welding the high-strength steel flash butt, It is an object of the present invention to provide a welding method in which weldability is improved and a healthy weld is formed.

도 1은 플래쉬 버트 용접에 의한 용접부의 경도를 보이는 그래프1 is a graph showing the hardness of the weld by the flash butt welding

도 2는 여러 가지 용접조건에 따라 얻은 용접부의 변형한계 값을 보이는 그래프2 is a graph showing the deformation limit values of welds obtained according to various welding conditions.

상기 목적을 달성하기 위한 본 발명은 고강도강으로 구성되는 소재를 맞대어 플래쉬 버트 용접하는 방법에 있어서, 용접에 의해 소멸되는 상기 소재의 전체 길이가 12-16mm이고, 1차 플래쉬 시간을 20-25초로 하고, 2차 플래쉬에 의한 이동거리가 5-8mm이고, 업셋에 의한 이동거리가 3-5mm인 것을 특징으로 하는 고강도강의 플래쉬 버트 용접방법에 관한 것이다.In order to achieve the above object, the present invention provides a method for butt welding a material composed of high strength steel, wherein the total length of the material extinguished by welding is 12-16 mm, and the first flash time is 20-25 seconds. And it relates to a flash butt welding method of high strength steel, characterized in that the movement distance by the secondary flash is 5-8mm, the movement distance by the upset is 3-5mm.

이하, 본 발명을 상세히 설명한다.Hereinafter, the present invention will be described in detail.

철강소재의 고강도화 및 수요증대에 의해, 그 생산에 있어서도 많은 애로점이 발생되고 있다. 본 발명의 용접방법에서 용접 대상인 고강도강으로서는 일반적인 고강도강을 적용할 수 있는데, 그 중에서도 하기 표1과 같은 화학조성을 갖는 고강도강을 적용하는 경우 보다 우수한 효과를 얻을 수 있다.Due to the high strength of steel materials and the increase in demand, many difficulties arise in the production thereof. As the high strength steel to be welded in the welding method of the present invention, general high strength steel may be applied. Among them, when the high strength steel having the chemical composition shown in Table 1 is applied, an excellent effect may be obtained.

성분ingredient CC SiSi MnMn PP SS AlAl N2 N 2 NbNb 함량(wt%)Content (wt%) 0.166-0.1940.166-0.194 0.45-0.550.45-0.55 2.70-2.902.70-2.90 ≤0.02≤0.02 ≤0.01≤0.01 0.015-0.050.015-0.05 ≤0.007≤0.007 0.04-0.050.04-0.05

플래쉬 버트 용접에 있어서 산화물 형성을 억제하고 완전한 용접부를 얻기 위해서는 플래쉬 과정에서 용접단면의 가열정도가 균일하여야 하며, 업셋 압력 또는 거리도 적절하게 적용하여야 한다. 플래쉬와 업셋에 의하여 용접모재가 용융소멸되는 거리를 언클램프(unclamp)거리라고 한다. 플래쉬 과정은 1,2차로 구분하여 1차 플래쉬 과정에서 미세한 플래쉬를 발생시켜 용융층을 균일하게 할 필요가 있으며, 2차 플래쉬 과정은 가속도에 의한 업셋 이전단계가 된다.In flash butt welding, in order to suppress the formation of oxides and to obtain a complete weld, the heating degree of the welding section must be uniform during the flash process, and the upset pressure or distance should be appropriately applied. The distance that the weld base material melts away by flash and upset is called the unclamp distance. The flash process needs to be divided into 1st and 2nd stages to generate a fine flash in the 1st flash process to make the molten layer uniform.

한편, 업셋시 빠른 속도로 가압하여야 한다. 그렇지 않으면 용접단면에 산화물이 형성하여 문제가 된다. 플래쉬 직후 가압시 산화물 형성을 억제하기 위하여 초기 업셋은 2차 플래쉬과정과 같은 가속도로 실시하며, 최종적으로 높은 전류와 함께 가압하게 된다. 그리고, 맞댄 면이 서로 어긋나게 되는 경우도 있으므로 조심하여야 한다.On the other hand, it must be pressurized at high speed during upset. Otherwise, oxides are formed on the welded end face, which is a problem. In order to suppress oxide formation during pressurization immediately after the flash, the initial upset is carried out at the same acceleration as the secondary flash process, and finally pressurized with a high current. Also, care must be taken because the facing surfaces may be displaced.

본 발명에서는 용접에 의해 소멸되는 소재의 전체 길이 즉 언클램프의 거리가 12-16mm인 것이 바람직하다.In the present invention, the total length of the material disappeared by welding, that is, the distance between the unclamps is preferably 12-16 mm.

상기 언클램프의 거리가 12mm미만인 경우는 가열되어 소멸되는 양이 적으므로 충분한 가압변형이 되지 못하고 냉접과 같은 결과를 초래하게 되는 문제가 있고, 그 거리가 16mm를 초과하는 경우는 많은 양이 소멸되어야 하지만 가압시 가열/용융된 부분이 완전히 배출되지 못하여 용접부에 용융금속이 잔존하여 결함을 유발할 가능성이 매우 높기 때문이다.If the unclamp distance is less than 12mm, the amount of heat dissipation is small, so there is a problem that it is not sufficiently pressurized and results in cold welding, and when the distance exceeds 16mm, a large amount must be dissipated. However, when pressurized, the heated / melted part is not completely discharged, and there is a high possibility of causing a defect due to molten metal remaining in the welded part.

또한, 본 발명에서는 1차 플래쉬 시간을 20-25초로 하는 것이 바람직하다.In the present invention, it is preferable to set the primary flash time to 20-25 seconds.

상기 1차 플래쉬는 용융층을 균일하게 행하는 것으로, 그 시간이 20초 미만인 경우는 충분히 가열되지 않고, 25초를 초과하는 경우는 가열영역이 너무 커서 가열되고 밀린 후 남는 부분이 용접부 결함으로 작용하기 때문에 20-25초로 한다.The primary flash is a uniformly molten layer. If the time is less than 20 seconds, the primary flash is not sufficiently heated. If it is more than 25 seconds, the heating zone is too large to be heated and pushed to act as a weld defect. Therefore, 20-25 seconds.

또한, 본 발명에서는 2차 플래쉬에 의한 이동거리가 5-8mm인 것이 바람직하다.In the present invention, it is preferable that the moving distance by the secondary flash is 5-8 mm.

상기 2차 플래쉬는 가속도에 의해 행해지는 과정으로서, 그 이동거리가 5mm미만이거나 8mm를 초과하는 경우는 가열된 영역에 알맞는 이동이 행해지지 않는 것이다.The secondary flash is a process performed by acceleration, and when the moving distance is less than 5 mm or more than 8 mm, the movement appropriate to the heated area is not performed.

또한, 본 발명에서는 업셋에 의한 이동거리가 3-5mm인 것이 바람직하다.In addition, in the present invention, it is preferable that the moving distance by the upset is 3-5 mm.

상기 업셋은 빠른 속도로 가압하는 것으로, 가압시 산화물 형성을 억제하기 위하여 초기 업셋은 가속도로 실시하며, 최종적으로 높은 전류와 함께 가압하게 된다. 이때, 업셋은 3-5mm의 이동거리로 행하는 것이 바람직하며, 초기 업셋은 1-2mm, 이후는 2-3mm가 바람직하다.The upset is pressurized at a high speed. In order to suppress the formation of oxide during the pressurization, the initial upset is accelerated and finally pressurized with a high current. At this time, the upset is preferably carried out with a moving distance of 3-5mm, the initial upset is preferably 1-2mm, after 2-3mm is preferred.

이하, 실시예를 통하여 본 발명을 보다 상세히 설명한다.Hereinafter, the present invention will be described in more detail with reference to Examples.

실시예Example

상기 표1과 같은 조성의 고강도강을 하기 표2와 같은 용접조건으로 플래쉬 버트용접을 행하였다.High-strength steel having the composition shown in Table 1 was subjected to flash butt welding under the welding conditions as shown in Table 2 below.

비교예1Comparative Example 1 비교예2Comparative Example 2 비교예3Comparative Example 3 비교예4Comparative Example 4 비교예5Comparative Example 5 발명예Inventive Example 비교예6Comparative Example 6 비교예7Comparative Example 7 비교예8Comparative Example 8 Jump(초)Jump (seconds) 1010 1010 1010 1010 2020 1010 1010 1010 1010 예비플래쉬(초)Preliminary Flash (sec) 1One 1One 1One 1One 1One 1One 1One 1One 1One 1차플래쉬(초)1st flash (sec) 2525 27.527.5 37.537.5 4040 5050 2525 1515 3030 3030 2차플래쉬(mm)Secondary flash (mm) 88 99 10.510.5 1010 66 66 4.54.5 4.54.5 4.54.5 1차업셋(mm)Primary upset (mm) 2.02.0 1.51.5 1.51.5 1.51.5 1.01.0 1.01.0 1.01.0 1.01.0 0.50.5 2차업셋(mm)Secondary upset (mm) 33 22 2.52.5 2.52.5 22 22 1.51.5 1.51.5 2.02.0 언클램프(mm)Unclamp (mm) 1818 1818 2222 2222 1414 1414 1010 1010 1010

상기 표2의 조건에 의한 용접실시 결과에 따르면, 언클램프의 거리가 16mm를 초과하는 경우에 있어서는 가압시 가열(용융)된 부분이 완전히 배출되지 못하여 용접부에 용융금속이 잔존함으로 해서 결함이 유발되었다. 한편, 언클램프의 거리를 12mm미만으로 행한 경우에 있어서는 가열되어 소멸되는 양이 적어 충분한 가압변형이 되지 못하고 냉접과 같은 결과를 초래하였다.According to the result of welding under the condition of Table 2, when the distance of unclamping exceeds 16mm, the heated (melted) part is not completely discharged when pressurized, and the defect is caused by the molten metal remaining in the welding part. . On the other hand, when the unclamping distance was less than 12 mm, the amount of heating and extinguishing was small, resulting in insufficient pressurization and resulted in cold welding.

본 실시예에서는 상기 표2와 같은 조건으로 용접된 용접부에 대한 평가를 행하였는데, 플래쉬 버트 용접부에 대한 경도분포는 도 1에서 보는 바와같이, 용접부가 모재에 비하여 높은 경도를 나타내고 있으며, 모든 용접조건에서 유사한 결과를 얻을 수가 있었다.In the present embodiment, the welds welded under the conditions shown in Table 2 were evaluated. The hardness distribution of the flash butt welds is higher than that of the base material, as shown in FIG. Similar results were obtained.

한편, 플래쉬 버트 용접부에 대한 평가에 있어서, 가장 간편하게 적용할 수 있는 방법은 성형성 평가의 방법으로 에릭센(Erichsen)시험이라고 하는 것이 있다. 이것은 소형 볼을 이용하여 용접부가 파단될 때까지 압출하여 나간 거리를 상호비교하는 방법이다. 따라서, 성형성이 우수한 경우에는 그 거리가 큰 것으로 그 만큼 용접부가 상대적으로 건전하다고 평가할 수 있다.On the other hand, in the evaluation of a flash butt welded part, the method which can be most simply applied is called the Erichsen test as a method of formability evaluation. This is a method of mutually comparing the distance extruded by using a small ball until the weld is broken. Therefore, when moldability is excellent, the distance is large, and it can be evaluated that a weld part is comparatively sound by that much.

본 실시예에서는 상기 표2와 같은 용접조건에 의해 용접된 용접부에 대하여, 성형성 평가(에릭센 시험)를 하고, 그 결과를 도 2에 나타내었다.In this embodiment, the weldability welded under the welding conditions shown in Table 2 was evaluated for formability (Ericsen test), and the results are shown in FIG.

도 2에서 알 수 있는 바와같이, 본 발명의 조건을 만족하는 발명예는 비교예 (1-8)에 비하여 우수한 값을 나타내었다.As can be seen from Figure 2, the invention example that satisfies the conditions of the present invention showed an excellent value compared to Comparative Example (1-8).

상술한 바와같은 본 발명에 의하면, 고강도강의 플래쉬 버트 용접시 플래쉬과정과 업셋과정의 조건을 적절히 제어하여, 기존의 용접조건에 의해 얻어진 용접부에 비하여 성형성이 1.5-2.0배 정도 우수한 용접부가 형성되는 효과가 제공된다.According to the present invention as described above, by welding the high-strength steel flash butt conditions appropriately control the conditions of the flash process and the upset process, the weld portion is formed 1.5-2.0 times better than the weld portion obtained by the conventional welding conditions is formed The effect is provided.

Claims (2)

고강도강으로 구성되는 소재를 맞대어 플래쉬 버트 용접하는 방법에 있어서,In a method of welding butt welding a material composed of high strength steel, 용접에 의해 소멸되는 상기 소재의 전체 길이가 12-16mm이고, 1차 플래쉬 시간을 20-25초로 하고, 2차 플래쉬에 의한 이동거리가 5-8mm이고, 업셋에 의한 이동거리가 3-5mm인 것을 특징으로 하는 고강도강의 플래쉬 버트 용접방법.The total length of the material extinguished by welding is 12-16mm, the first flash time is 20-25 seconds, the travel distance by the secondary flash is 5-8mm, and the travel distance by upset is 3-5mm. Flash butt welding method of high strength steel, characterized in that. 제 1 항에 있어서,The method of claim 1, 상기 고강도강은 중량%로 C:0.166-0.194%, Si:0.45-0.55%, Mn:2.70-2.90%, P:0.02%이하, S:0.01%이하, Al:0.015-0.05%, N2:0.007%이하, Nb:0.04-0.05%를 함유하는 것을 특징으로 하는 고강도강의 플래쉬 버트 용접방법.The high strength steel is C: 0.166-0.194%, Si: 0.45-0.55%, Mn: 2.70-2.90%, P: 0.02% or less, S: 0.01% or less, Al: 0.015-0.05%, N 2 : A flash butt welding method of high strength steel, characterized by containing 0.007% or less and Nb: 0.04-0.05%.
KR1019990029310A 1999-07-20 1999-07-20 A Method of Flash Butt Welding for High Strength Steel KR100325352B1 (en)

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Cited By (1)

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Publication number Priority date Publication date Assignee Title
KR100482222B1 (en) * 1999-12-15 2005-04-13 주식회사 포스코 A Method of Flash Butt Welding for High Carbon Steel

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JPS6025229B2 (en) * 1978-09-19 1985-06-17 新日本製鐵株式会社 Flash welding method
JPS59147782A (en) * 1983-02-10 1984-08-24 Nippon Steel Corp Flash butt welding method
JP2864338B2 (en) * 1993-11-12 1999-03-03 新日本製鐵株式会社 Flash welding method for high strength steel
KR0147719B1 (en) * 1995-03-03 1998-11-02 서순화 Method for manufacturing high-strength ni-cr-v steel material for conveyor chain

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR100482222B1 (en) * 1999-12-15 2005-04-13 주식회사 포스코 A Method of Flash Butt Welding for High Carbon Steel

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