JPS5910478A - Welding method of stainless steel and low alloy steel - Google Patents

Abstract

PURPOSE:To prevent the generation of high temp. crack and to obtain a welded joint of dissimilar materials having high reliability in welding of dissimilar materials by subjecting an ''Inconel'' welding material to build up welding at a low heat input then to build up welding at a high heat input on the groove face on a low alloy steel side. CONSTITUTION:An ''Inconel'' welding material is build up welded 2 in 1-2 layers by TIG or plasma welding on a low alloy steel 1 side in welding of a stainless steel and a low alloy steel. Since the weld heat input in this state is low, there is no danger of high temp. crack. A backing strip 4 is then mounted, and the ''Inconel'' welding material is built up 3 by a welding method with a high heat input to the extent at which the projecting part of the groove can be worked; thereafter, the material is subjected to a prescribed edge preparation. The problem of dilution in the low alloy steel 1 side to be generated in the root pass is solved by the above-mentioned method. The 2nd and succeeding layers are the mere penetration to the side faces alone; therefore, the degree of penetration is low and the possibility for high temp. crack is eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to 15 methods for welding stainless steel and low alloy steel.

Traditionally used in piping for boilers, chemical plants, etc.

The high temperature side is made of stainless steel, and the low temperature side is made of stainless steel.

Low alloy steel is used. Therefore, something like this.

In structures, welded joints of stainless steel and low alloy steel with 20 dissimilar materials are required, or welded 4A materials with the same composition as stainless steel are used for such 4A dissimilar welded joints.

For example, thermal stress is generated due to the difference in the coefficient of thermal expansion of the drawing materials, and the difference in the amount of Cr causes a decrease in strength due to decarburization at the boundary of the weld, which can lead to cracks. In order to eliminate this drawback, conventionally welding of the above-mentioned joints was performed using stainless steel with a coefficient of thermal expansion.

Decarburization occurs between low alloy steels and due to the difference in Cr content.

Inconel welding consumables with high N1 are often used, which do not cause problems, but when welding Inconel welding material to low alloy steel, the penetration rate is affected due to dilution problems.

There was a risk of high temperature cracking occurring. That.

For this reason, in first layer welding, the heat input can be lowered by lowering the welding current and setting the welding speed by -1.

It is said that strict control of welding execution is necessary.
'There were drawbacks.

1"I object of this invention is to eliminate the above-mentioned drawbacks of the prior art, to prevent hot cracking of dissimilar metal welded joints, and to obtain highly reliable dissimilar metal welded joints. 211 In short, the present invention provides an Inconel-based welding material.

The problem of dilution was solved by overlaying the steel on the low alloy steel side and creating a groove. .

1;', this invention will be explained based on the drawings. No. 1
The figure is a side sectional view of the groove shape when all 11'i'i'1' dynamic TIG welding is performed, and the protruding part of the groove, which is the initial layer, is made with Inconel-based welding AA material to a cross section of 2 mm x 2 mm.
Do some overlay welding. The overlay welding method will be explained with reference to FIG. 2. Inconel-based low alloy steel 1 is used.

1 of TTG welding or plasma welding using welding 4A material
1 to 2 layers of overlay 2 using a welding method with low welding heat input such as 0.
However, due to the low welding heat input, high temperature cracking occurs.

There's no danger. A backing metal 4 is attached to the weld, and welding 3 is performed using Inconel-based welded paulownia material to the extent that the protruding part of the groove can be machined.In this case, there is a risk of high-15 temperature cracking when welding. Therefore, a method with a considerably high welding heat input, such as shielded arc welding, may be used.In this way, after applying the overlay 3 using Inconel welding material, the prescribed groove processing is performed. This is what we do.
20-1. As explained above, the method of the present invention provides an in-line method.

Connel-based welding material is used, but in the first layer.

This solves the problem of dilution on the low-alloy steel side, and after the 2° layer, melting is performed only on the side surfaces.

The rate is low and there is no need to worry about high temperature cracking. Therefore, it is high in dissimilar welded joints of stainless steel and low alloy steel.

The risk of thermal cracking is eliminated, so it can be used in boilers and chemical plastics.

The reliability of Difference 4-A welded joints is significantly improved, and the restrictions during welding as described in -1 are reduced.
10

[Brief explanation of drawings]

Figure 1 shows the shape of the welding amount for automatic TiG welding all around. The side cross-sectional view, FIG. 2, shows the overlay welding according to the present invention. FIG. Explanation of symbols 1・)1
...Low alloy steel 2, In-contact by TIG welding or plasma welding. Welding based on metal welding (JI overlay 3... Inconel welding material by covered arc welding. Overlay 204... Patent attorney representing the backing fund Junnosuke Nakamura 1 Figure 2

Claims (1)

[Claims] In welding stainless steel and low-alloy steel, inconel-based welding is performed in advance by TIG welding or plasma welding on the low-alloy (copper value) groove at the location corresponding to the first layer weld of the stainless steel. Overlay welding and welding. A method for welding stainless steel and low-alloy steel, which is characterized in that a counterfeit metal is then attached, and Inconel-based welding material is overlay-welded using the 10 method of welding, which requires high welding heat input. Method.