JPS60133975A - Build-up welding method - Google Patents

Abstract

PURPOSE:To prevent the decrease in the corrosion resistance at the end of a weld zone and to prevent the decrease in the strength of a base metal consisting of carbon steel or low alloy steel or the like by building up a corrosion resistant material such as a stainless steel or the like by plural passes of lap welding on said base metal, welding further the end part by a high nickel alloy and removing the dilute part of the base metal. CONSTITUTION:A corrosion resistant material of a stainless steel or the like is built-up 12 by plural passes of lap welding on a base metal 11 consisting of a carbon steel or low alloy steel, etc. and further the end part 12 thereof is subjected to welding 15a, 15b of a high nickel alloy. The carbon of the base metal transfers to the welded stainlss steel and dilute parts 14a, 14b of the carbon are made on the base metal but if the high nickel alloy having high strength is welded 15a, 15b to the weld end part 13 where stress concentrates, the parts 14a, 14b are eliminated and the transfer of the carbon is obviated as well. The deterioration in the corrosion resistance in the part 13 and the decrease in the strength of the base metal are prevented. The generation of a crack is prevented as well. A stainless steel may be build-up welded to the build-up part 12 in proximity to the Vee opening.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a build-up in which a base material made of carbon steel or low-alloy steel is coated with a corrosion-resistant material such as stainless steel. This relates to a welding method.

``Prior art'' Generally, vertical steel (
The inner surface of containers and piping made of carbon steel (low-alloy steel), and the welding surface of vertical plain steel (low-alloy steel) pipes and plates when welding stainless steel pipes and plates to carbon steel (low-alloy steel) pipes and plates. In other words,
Build-up welding of a corrosion-resistant material made of carbon steel or low-alloy steel side 1c of non-stainless steel or kudzu metal that approximates it is carried out on the part that will become a dissimilar metal joint.

By the way, when non-ferrous steel is build-up welded to the carbon steel (low alloy steel), the following M solid point occurs, especially due to the large difference in carbon content between the two.

That is, for example, when welding carbon steel and rustless steel, we will explain the case where welding a filler metal made of stainless steel or a metal similar to it to the welding surface of carbon steel.
As shown in Fig. 1, when a build-up layer 3 is formed by welding the filler metal 2 to the welding surface of the carbon steel 1 in multiple passes, the carbon in the carbon ml increases as shown by the arrow in the figure. It precipitates into the filler metal 2 and causes dilution in the carbon steel 1.

When such a dilution phenomenon occurs, the corrosion resistance of the filler metal made of stainless steel or the like deteriorates, and the mechanical strength of the carbon steel 1 tends to decrease. In addition, when welding the carbon steel 1ζ and the stainless steel 4, the welding heat causes a difference in thermal expansion and contraction between the carbon steel 1 and the build-up layer 3, and the interface between them, especially the build-up layer 3. The end of (
There is a risk that high stress will occur at the upper and lower ends (in Fig. 1), inducing cracks.

[@Akira's purpose] The present invention has been made in view of the circumstances of the prior art described above, and is a method for laminating a corrosion-resistant material such as stainless steel on a base material made of carbon steel or low alloy steel. The object of the present invention is to provide a build-up welding method that prevents a decrease in strength at the boundary between the two and suppresses the occurrence of cracking.

[Structure of the Invention] The present invention involves welding a corrosion-resistant material such as non-staining steel to a base material made of carbon steel or low alloy steel using multiple passes with the weld beads partially overlapping each other. At the same time as forming a layer, the diluted part of the base metal that occurs under the weld bead in the previous stage is sequentially removed when forming the weld bead in the latter stage,
Weld along the weld bead formed by either the first pass or the last pass with a filler metal consisting of a high nickel alloy to remove the diluted portion of the base metal remaining below the weld bead. By doing so, most of the diluted portion that occurs in the built-up portion of the base material is removed.

"Example" Hereinafter, the overlay welding method according to the present invention will be applied to butt welding between different metals, and when the dissimilar metals are carbon steel or low alloy steel and stainless steel, the butt welding method is applied to the butt surface of carbon steel or low alloy steel. An applied example will be explained based on FIG. 2.

The overlay welding method shown in this example is first shown in Fig. 2(a).
As shown in FIG. 1, the welding bead (12) made of multiple passes of the welding bead (12) made of a corrosion-resistant material such as stainless steel is applied to the mating face (ζ) of the base material 11 made of carbon steel, with the welding beads (12) partially overlapping each other ( In this embodiment, the build-up layer 13 is formed on the abutting surface of the base material 11 by sequentially welding the weld beads 12 so as to overlap each other by approximately half the width of each weld bead 12. When forming the build-up layer 13, the diluted portion of the base #11 caused by the weld bead 12 in the previous stage is sequentially removed approximately half by half by the weld bead 12 in the latter stage, as shown by the chain line in FIG. 2(a). As shown, * below the bath welding bead 12a of the first pass and the welding bead 12b of the last pass (i.e., at both edges of the abutting surfaces of the base metal 11, at the edges in the vertical direction in FIG. 2(a)). , the dilution parts 14a and 14b remain in a closed state.

Next, as shown in FIG. 82(b), a filler metal made of high nickel alloy is applied onto the previous Iid weld beads 12a and 12b so that the weld beads 15a and 15b form the weld beads 12a and 12b.
Welding is performed so that the weld beads 12a and 12b partially overlap each other (in this embodiment, approximately half the width of the weld beads 12a and 12b overlaps). By welding the filler metal made of the nickel alloy, the diluted portions 14a and 14b remaining on both edges of the abutting surfaces of the base metal 11 are removed to complete the overlay welding of this embodiment.

When welding the filler metal made of the high nickel alloy, the base metal 11 under the weld beads 15a and 15b is There is no risk of creating a diluted part. Therefore, after the above-mentioned build-up welding is completed, the diluted portion can be removed over the abutting metal surfaces of the base metal 11.

On the other hand, as mentioned above, the base material 11 that has been in contact with the build-up layer 13# has a number as shown in FIG. 3(a).
After the groove 16 is formed by cutting and the weld beads 15B and 15b on both edges of the base metal 11 are removed together with part of the weld beads 12a and 12b, a third
As shown in Figure (b) I, a base material 17 made of stainless steel is welded with a filler metal 18JC made of the same material as the stainless steel.

In welding between different metals, such as the base metal 11 made of carbon steel and the base metal 17 made of stainless steel, since there is no dilution part in the base metal 11ζ, the influence of heat input during bath welding and residual stress after welding are reduced. The above-mentioned amount also suppresses the effect of acting on the boundary between 11 and the built-up layer 13, thereby preventing the occurrence of cracks and the like.

On the other hand, FIG. 4 shows another embodiment of the present invention, in which a built-up nozzle 13 is formed on the abutting surfaces of the base material 11 as shown in FIG. 4(a), and then both sides of the base material 11 are The edges are removed by cutting as shown in Fig. 4, and filler metal 20a made of a high nickel alloy is inserted into the grooves 19a-19b formed by the cutting operation, as shown in Fig. 4(C). The welding is done so that the groove 20b is embedded. According to this method, most of the diluted portions on both edges of the base metal 11 are mechanically removed, and the remaining diluted portions are then removed during welding of the filler metals 20a and 20b made of high nickel alloy. This makes the removal of the dilution part even more reliable.

5 and 6(a) show an example in which the present invention is applied to the end face of a nozzle lined with a durable material, which is continuous with the lining material 22 on the inner surface of the nozzle 21, In addition, a filler metal made of a corrosion-resistant material is welded over the end face of the nozzle 21 in a number of passes to form a built-up layer 1.
3 is formed, a filler metal 23 made of a high nickel alloy is welded to the outer edge of the end face in a state where it overlaps with the terminal end of the build-up layer 13. 6th
FIG. 6(b) is another embodiment of FIG. 6(a), and the outer 111
The diluted part of the nozzle base material 21 in the 11iR part is mechanically removed and filled with a filler metal 23 made of a high nickel alloy and welded. In these embodiments, the filler metal 23 made of a high nickel alloy may be welded to only one location on the outer periphery as described above.

"Effects of the Invention" As explained above, the present invention provides the following excellent effects.

■ It is possible to prevent a decrease in the corrosion resistance of a corrosion-resistant material by removing most of the I-work in the diluted part in the base metal that occurs during overlay welding, and also to prevent a decrease in the strength of the base metal. I can do it.

■ When dissimilar metals are brought into contact with the base metal through a build-up layer, if a difference in thermal expansion/contraction occurs between the base metal and the build-up layer due to heat input during welding, or after welding, Even if residual stress occurs, the influence on the boundary between the base material and the built-up layer can be suppressed as much as possible, thereby preventing the occurrence of cracks and the like. As a result, bath welding of dissimilar metals is facilitated.

[Brief explanation of the drawing]

In the drawings, FIG. 1 is a schematic diagram showing an example of a conventional build-up welding method, FIG. 2 is a process diagram showing an embodiment of the present invention, and FIG. Fig. 4 is a process chart showing another embodiment of the present invention, and Figs. tfJ5 and 6 show an example in which the present invention is applied to a nozzle. Something,
Figure 5 is a partially sectional side view of the nozzle, and Figure 6 is a side view of the nozzle.
It is an enlarged view of the V1 part of the figure. 11...Base metal, 12...Weld bead,
12a... (first pass) weld bead, 12
b...Weld bead (of the final pass), 13...
...Filled layer, 14a. 14b... Dilution section, I5a, 15b...
・Bath welding bead, 19 a, 19 b --- Groove, 20 g, 20 b --- Filler metal, 23.
...Filler metal. Applicant Ishikawajima Harima Electric Industry Co., Ltd. Figure 1 Figure 2 Figure 3 Figure 4 20° (0) Figure 5!

Claims (1)

[Claims] A non-corrosion resistant material is welded to a base material such as carbon steel or low alloy steel with multiple passes of the S-weld bead partially overlapping each other to form the fillet f-. The diluted portion of the base metal that occurs under the weld bead is sequentially removed during the subsequent weld bead formation, and the diluted portion under the weld bead is removed along the weld bead formed by either the first pass or the final pass. 1ζ A build-up welding method characterized by welding with a filler metal made of a high nickel alloy in order to remove the remaining diluted part.