JPH05169295A - Manufacture of welded crossing - Google Patents

Abstract

(57) [Abstract] [Purpose] A method for manufacturing a welded crossing for a railroad turnout that is free from wear resistance, damage resistance, and HAZ liquefaction cracking. [Structure] In a welding crossing composed of a nose rail and a wing rail, when welding the welding groove corresponding to the rail head, C: 0.5 based on the total weight of the welding rod.
Contains over ~ 1.0% and CaO on the outer circumference of the welding rod core wire.
Use a coated arc welding rod coated with a coating composition so that the ratio of / CaF ₂ is in the range of 1.3 to 1.0, or C: 0.85 to 1.5 with respect to the total weight of the filler metal. % Welding crossing manufacturing method by continuous multi-layer welding by carbon dioxide gas shielded arc welding method using solid wire for welding or composite wire for welding containing 10% as a consumable electrode. [Effect] The present invention is a method of manufacturing a welded crossing, which has solved the problems of wear resistance and damage resistance, which have been problems in the past, and is highly practical in terms of work efficiency.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method of manufacturing a welded crossing for a railway turnout.

[0002]

2. Description of the Related Art Conventionally, welding crossings for railway turnouts include manganese crossings using high manganese cast steel and welding crossings using general carbon steel. Compared with welded crossings, manganese crossings are superior in wear resistance and ductility, and have an advantage in durability. However, since welding with front and rear tracks is a dissimilar material joint, it is difficult to apply welding, so mechanical joints with joint plates are usually adopted, which is a significant drawback in the current situation where speed improvement and noise reduction of trains are desired. Has become a problem. On the other hand, in the case of welding crossing, since carbon steel having the same composition as the front and rear tracks is used, it can be relatively easily connected by welding, which is advantageous in terms of speed improvement and noise reduction of the train. However, the conventionally manufactured weld crossing uses consumable electrode arc welding, and its weld metal composition has a low carbon content (C <0.38%), and in order to improve the hardenability, Cr, Since alloys such as Mo, Ni, and B are added, there are problems in wear resistance, damage resistance, and HAZ liquefaction cracking. In particular, Japanese Laid-Open Patent Publication No. 1-197093 discloses a method of using a wire containing 0.7 to 0.82% of C for the purpose of compensating for the inferior wear resistance compared to manganese crossing. .. This method is not a general method because it is a non-consumable electrode arc welding method using TIG welding and has a problem of poor welding efficiency and extremely poor productivity.

[0003]

As described above, in the filler metal used in the prior art, the welding heat affected zone (HA
The possibility of liquefaction cracking of Z) cannot be completely prevented. The main factor of these is C between weld metal and rail.
Since there is a difference in the amount and the solidification temperatures of the two are significantly different, due to the solidification shrinkage of the weld metal, the remelted and liquefied austenite grain boundaries near the melting boundary line of the rail with high C and low solidification temperature are caused. This is a result of the addition of shrinkage strain.
On the other hand, for wear resistance and fatigue damage resistance of rails, a fine pearlite structure having a high hardness and a high C eutectoid structure (containing about 0.8% of C) is effective, Therefore, the bainite structure obtained by the filler material used in the prior art has problems such as inferior wear resistance and fatigue damage resistance as compared with the high C pearlite structure even if the hardness is the same. Also, since the welding crossing manufacturing has a complicated shape, it is necessary to apply a welding method that is simple and highly efficient, and a covered arc welding method using a large diameter welding rod, and as much as possible. A method that enables continuous welding without removing slag, or a continuous multi-layer welding method using a consumable electrode type carbon dioxide shield arc welding method is desirable.

[0004]

DISCLOSURE OF THE INVENTION The present invention should solve the above problems in the prior art. As a result of intensive studies by the present inventors, the welding formed by the conventional filler metal It was found that the above-mentioned problems occur because the metal has a remarkably different composition from the base metal rail, and the weld metal has a high C similar to that of the base metal rail which has been considered unsuitable for conventional welding. A method for repair welding of rails having a type pearlite composition was found. The gist of the invention is as follows: (1) In a welding crossing composed of a nose rail and a wingle, the total weight of the welding rod when welding the welding groove corresponding to the rail head. On the other hand, C: more than 0.5
Contains 1.5% and CaO / C on the outer circumference of the welding rod core wire
A method for producing a welding crossing, characterized in that continuous multi-layer welding is performed using a coated arc welding rod coated with a coating composition so that the ratio of aF ₂ is in the range of 1.3 to 1.7 (2). In a welding crossing composed of a nose rail and a wing rail, when welding a welding groove corresponding to the rail head, C: 0.85 to the total weight of the filler metal.
A method for producing a welding crossing, characterized by carrying out continuous multi-layer welding by a carbon dioxide gas shield arc welding method using a solid welding wire or a composite welding wire containing 1.5% as a consumable electrode (3). After performing the manufacturing process of the welding crossing according to (1) or (2) above, the corresponding welded portion is heated to 900 ° C. or higher, and then slowly cooled by compressed air injection to produce a welding crossing. It is in.

[0005]

The present invention will be described in detail below with reference to the drawings. FIG. 1 is a plan view showing the entire welding crossing. Here, the crossing means that which constitutes a portion where rails intersect in the branching device. The welding crossing is a crossing in which a nose rail and a wing rail are assembled by welding. Since it is difficult to weld manganese crossings and ordinary rails, we started to develop them as high-speed branching crossings for the purpose of reducing the increase in maintenance amount due to high-speed operation in 1987 at the former JNR, and are currently 50N, 60
It is used in a Kg rail high-speed switch. Since the welding crossing is an important factor that determines the durability, the welding performance must be strictly controlled. Against such a background, as shown in FIG. 1, the welding crossing has a pair of nose shifts having the same cross-sectional shape as the normal rails symmetrical to each other between the pair of wing rails 2.2. -It is formed by welding with the back 3.3 back to back, heat-treated, and then held by welding.

FIG. 2 is a sectional view taken along the line A--A of FIG. 1. In general, a pair of symmetrical nose rails 3.3 have a head 4 which is downwardly welded in multiple layers at the cutting edge and a base. The spout 6 is also welded at the cleaved point, and the abdomen 5 is hollow. The hollow formed in the abdomen 5 becomes smaller toward the tip of the nose rail.
On the other hand, the welded nose rail 3.3 is welded and integrated only with the wing rail 2.2 and the base portion 7 located on both sides thereof to form a fixed crossing. The welded crossing 1 is butt-welded at its front and rear ends so as not to have a seam broken line portion to form a branching device.

FIG. 3 is a cross-sectional view of a normal welding point of the weld crossing. In this way, when the rails are processed and assembled so as to be piled up in parallel, the portion to which the present invention is applied corresponds to the rail head portion of the welding groove formed on the head portion and the bottom portion of the rail. It is in the welding groove A part. The section A shows a cross-sectional view in which the rail head welding portion is laminated and overlaid. Since the groove is deep, downward build-up welding of multiple passes is performed at the same time as the formation of the bottom portion as shown by numbers (1) to (11), and two or more layers are continuously inverted and alternately performed simultaneously with the bottom portion. At this time, pay close attention to the start and end treatments of each welding pass, and make sure that they are exposed on the rail head surface. This is because attention must be paid to blowholes, slag entrainment, and hot cracking at the end. It is a means necessary to completely prevent the occurrence of these defects.

The component of the welding rod core wire, which is the first aspect of the present invention, is C: more than 0.5 to 1.
The range is 0%. The reason for setting this range is C 0.5%
If it is less than the following, a significant difference in the amount of C from the base metal rail will occur, and therefore the solidification temperatures of the weld metal and the rail will differ greatly, so that the vicinity of the melting boundary line of the rail with high C and low solidification temperature. The shrinkage strain generated due to the solidification shrinkage of the weld metal is added to the re-melted and liquefied austenite grain boundary, resulting in liquefaction cracking of the weld heat affected zone (HAZ) and, on the other hand, the resistance of the rail. The wear and fatigue damage resistance are regulated because a fine pearlite structure having a high hardness and a high C eutectoid structure is effective. The reason why the upper limit is set to 1.0% is that when the C content of the total weight% of the welding rod exceeds 1.0%, the C content of the weld metal exceeds 0.9 and coarse cementite precipitates in the weld metal, The metal becomes extremely brittle. Also, from the viewpoint of welding workability, the viscosity of the welding slag is excessively lowered, and the viscosity of the welding slag wraps around the tip of the welding rod, making it easy to get entangled and hindering a smooth welding rod.

Next, CaO / CaF is formed on the outer periphery of the welding rod core wire.
_The reason why the coated arc welding rod coated with the coating composition so that the ratio of ₂ is in the range of 1.3 to 1.7 is used is that the composition of the welding rod according to the present invention is used as a slag forming agent. The optimum range is determined from various conditions such as gas generation arc stability. That is, when the ratio of CaO / CaF ₂ in the coating material is less than 1.3, the viscosity of the slag becomes high and it is difficult to remove it from the molten pool, which is not preferable in welding work. On the other hand, if the ratio of CaO / CaF ₂ exceeds 1.7, the slag viscosity becomes high again and the slag generation amount also increases, so that a sound and smooth welding rod cannot be performed. Therefore, for these reasons, the ratio of CaO / CaF ₂ in the coating agent is defined as 1.3 to 1.7.

Furthermore, the reason why C0.85-1.5% of the total weight of the filler metal is used as a component of the welding solid wire or welding composite wire which is the second aspect of the present invention is the coating. Unlike the arc welding rod, it is premised that carbon dioxide gas is used as a shield gas, and the consumption of each component in the filler metal is taken into consideration. Therefore, the optimum C content is high, so that it is less than 0.85%. Similar to the above, shrinkage strain generated due to solidification shrinkage of the weld metal is added to the re-melted and liquefied austenite grain boundary near the melting boundary of the base metal rail.
This is because liquefaction cracking of AZ) occurs. But 1.5%
If it exceeds 1.0, the C content of the weld metal becomes too high, causing embrittlement of the weld metal and deterioration of welding workability. In addition, by heating the welded portion to 900 ° C. or higher and subsequently compressed air spraying, that is, by slowly cooling the temperature from 900 ° C. or higher to 300 ° C. at an average cooling rate of 1 to 5 ° C./min, the base metal A pearlite structure, hardness and joint strength similar to rails are obtained. That is, the tensile strength is 100 with a high C pearlite similar to the base material rail.
It is possible to obtain molten metal of kg / mm ² or more.

[0011]

【Example】

Example 1 Table 1 shows JIS used in manufacturing welded crossings.
The composition of the -60 kg carbon steel rail is shown. Using the rails having these compositions, the carbon content is contained in the conditions of the coating arc welding method shown in Table 2, that is, in the range of more than 0.5 to 1.0% with respect to the total weight of the welding rod. The coated arc welding methods using so-called welding rods A to C and Comparative Examples EF were used for the head of the rail and for the groove groove as shown in FIG. The welding work conditions at that time were: welding rod diameter: 4 and 5 mm, polarity: DC reverse polarity (rod +) DCRP, welding current: 150 to 200 A
(4 mm), 210 to 260 A (5 mm), voltage: 24
~ 27V, build-up speed: 10-14cm / min, preheating:
The temperature was 200 to 500 ° C. and the temperature between passes was 200 ° C. Table 3 shows the results of the performance and workability of the produced welding crossings. As is clear from this table, in the present invention, the pearlite structure has excellent wear resistance and damage resistance, no defects occur, and the work efficiency is high. On the other hand, the comparative example produced bainite having low wear resistance and caused high temperature HAZ liquefaction.

[0012]

[Table 1]

[0013]

[Table 2]

[0014]

[Table 3] Example 2 As in Example 1, Table 1 shows the composition of the JIS-60Kg carbon steel rail used in manufacturing the welded crossing. A filler material G shown in Table 4 is prepared by using rails having these compositions.
To a carbon dioxide gas shield arc welding method using a welding solid wire or welding composite wire containing C: 0.85 to 1.5% based on the total weight of the J-type filler metal as a consumable electrode, and Comparative Examples K and L were produced using the rail head in the groove portion as shown in FIG. The welding conditions at that time were: wire diameter: 1.6 mm, polarity: DC reverse pole, welding current: 220 to 300 A, voltage: 24 to 30 V, build-up speed: 12 to 18 cm / min, preheating: 200 to 500.
C., temperature between passes: 200.degree. Table 5 shows the performance and workability results of the manufactured welded crossings.
As is clear from this table, in the present invention, the pearlite structure has excellent wear resistance and damage resistance, no defects occur, and the work efficiency is high. On the other hand, the comparative example produced bainite having low wear resistance and caused high temperature HAZ liquefaction.

[0015]

[Table 4]

[0016]

[Table 5]

[0017]

As described above, the welding crossing manufactured by using the filler material according to the present invention in the welding groove portion of the rail head has the problems of wear resistance and damage resistance, which have been the conventional problems. It is to provide a welding method which is solved and which is highly practical in terms of work efficiency.

[Brief description of drawings]

FIG. 1 is a plan view showing the entire welding crossing,

2 is a sectional view taken along line AA of FIG.

FIG. 3 is a cross-sectional view of a normal welding point of the weld crossing.

[Explanation of symbols]

 1 Weld crossing 2 Wing glare 3 Nose rail 4 Head 5 Abdomen 6, 7 Base

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[Procedure amendment]

[Submission date] December 7, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0004

[Correction method] Change

[Correction content]

[0004]

DISCLOSURE OF THE INVENTION The present invention should solve the above problems in the prior art. As a result of intensive studies by the present inventors, the welding formed by the conventional filler metal It was found that the above problem occurs because the metal has a composition significantly different from that of the base metal rail, and the weld metal has a high C type pearlite composition similar to that of the base metal rail, which has been considered unsuitable for conventional welding. We have found a repair welding method for different rails. The gist of the invention is as follows: (1) In a welding crossing composed of a nose rail and a wing rail, when welding a welding groove portion corresponding to the rail head, C: 0. Over 5 ~
Contains 1.0% and CaO / C on the outer circumference of the welding rod core wire.
Manufacturing method of welding crossing, characterized in that continuous multi-layer welding is performed using a coated arc welding rod coated with a coating composition so that the ratio of aF ₂ is in the range of 1.3 to 1.7 (2) Nose rail In a welding crossing composed of a wing rail and a wing rail, when welding the welding groove corresponding to the rail head, C: 0.85 to the total weight of the filler metal
Welding crossing manufacturing method characterized by carrying out continuous multi-layer welding by a carbon dioxide gas shielded arc welding method using a solid welding wire or a composite welding wire containing 1.5% as a consumable electrode. ) Or (2), after performing the manufacturing process of the welding crossing described above, the corresponding welding part is heated to 900 ° C. or higher, and then slowly cooled by jetting compressed air.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0010

[Correction method] Change

[Correction content]

Furthermore, the reason why C0.85-1.5% of the total weight of the filler metal is used as a component of the welding solid wire or welding composite wire which is the second aspect of the present invention is the coating. Since it is premised that carbon dioxide gas is used as a shield gas unlike the arc welding rod, the consumption of each component in the filler metal is taken into consideration, and the optimum C amount is high, and therefore, if it is less than 0.85%, it is the same as above. As a result of addition of shrinkage strain caused by solidification shrinkage of the weld metal to the re-melted and liquefied austenite grain boundary near the melting boundary of the material rail, the weld heat affected zone (H
This is because liquefaction cracking of AZ) occurs. But 1.5%
If it exceeds 1.0, the C content of the weld metal becomes too high, causing embrittlement of the weld metal and deterioration of welding workability. In addition, by heating the welded portion to 900 ° C. or higher and subsequently compressed air spray, that is, by slowly cooling the temperature from 900 ° C. or higher to 300 ° C. at an average cooling rate of 1 to 5 ° C./s , the base metal A pearlite structure, hardness and joint strength similar to rails are obtained. In other words, high C pearlite, which is similar to the base material rail, has a tensile strength of 100 kg.
It is possible to obtain a molten metal of / mm ² or more.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0014

[Correction method] Change

[Correction content]

[0014]

[Table 3]

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0016

[Correction method] Change

[Correction content]

[0016]

[Table 5]

Front page continuation (72) Koichi Uchino 1-1, Tobata-cho, Tobata-ku, Kitakyushu City Inside Nippon Steel Co., Ltd. Yawata Works (72) Inventor Kazuo Sugino 1-1, Tobata-cho, Tobata-ku, Kitakyushu City New Japan Steel Works Co., Ltd. Yawata Steel Works (72) Inventor Koji Oishibashi 2-8-8, Mitsumachi, Kokubunji, Tokyo 38 Inside Railroad Research Institute of Japan (72) Inventor, Katsuyoshi Ueyama, Kojibun, Kokubunji, Tokyo 8-chome 38, Railway Technical Research Institute (72) Inventor, Muneyuki Ohara 2-chome, Hikarimachi, Kokubunji, Tokyo 38-38, Railway Technical Research Institute (72) Inventor, Mitsumasa Tatsumi, Kitsubuncho, Kokubunji, Tokyo 2-chome 38, Inside the Railway Technical Research Institute

Claims (3)

[Claims] 1. In a welding crossing composed of a nose rail and a wing rail, when welding a welding groove corresponding to the rail head, C:
A coating composition containing more than 0.5 to 1.0% and coated with a coating composition on the outer periphery of the welding rod core wire so that the ratio of CaO / CaF ₂ is in the range of 1.3 to 1.7. A method for producing a welded crossing, which comprises continuous multi-layer welding using a welding rod. 2. In a welding crossing composed of a nose rail and a wing rail, when welding a weld groove corresponding to the rail head, C:
Manufacture of a welding crossing characterized by continuous multi-layer welding by a carbon dioxide gas shield arc welding method using a solid welding wire or a composite welding wire containing 0.85 to 1.5% as a consumable electrode. Method. 3. After performing the manufacturing process of the welding crossing according to claim 1 or 2, the corresponding weld is 900 ° C.
A method for manufacturing a welding crossing, which comprises heating as described above and then performing gentle cooling by jetting compressed air.