JPS6363581A - Groove shape for electron beam welding - Google Patents

Abstract

PURPOSE:To detect the incomplete fusion by the nondestructive inspection by finishing the surface roughness of both sides or one side of the mating surfaces of a groove for the electron beam welding in a specific range. CONSTITUTION:The surface roughness of both sides 11a and 12a of the groove surfaces is finished roughly in the range of 25-250mum and a clearance 31 is allowed to exist in a state with the groove surfaces mated each other. Furthermore, only the groove surface 11b is finished roughly mentioned above and a clearance 32 is allowed to exist to perform the electron beam welding. At this time, a molten zone 4 contracts at the time of solidifying and the incomplete fusion zone 5 is made in a state with the surfaces press-contacted each other and projection parts of the groove surfaces finished roughly are crushed and recessed parts of the surfaces are not closely contacted and a clearance 33 is left. Accordingly, when the clearance is allowed to exist in the incomplete fusion zone, the detection by the nondestructive inspection such as the radiographic test, the ultrasonic examination, etc., is facilitated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a groove shape for electron beam welding of metal materials, which is widely applied as a means of producing heavy and medium industrial products.

[Conventional technology]

In electron beam welding, high-speed thermoelectrons collide with the part to be welded in X air to melt the part. therefore.

There is no gas contamination in the molten metal, and there is no occurrence of hydrogen-dependent cold weld cracking. Furthermore, compared to other welding methods, the amount of melting is extremely small, so there is little welding deformation, and the dimensional accuracy after welding is excellent.

This is because the welding method has such characteristics.

It has come to be used not only for thin and medium-thick plates, but also for thick plates. Figure 8 shows the groove shape of a very common butt weld of a flat plate 1.2, and the conventional groove shape is finished smooth so that the two butted surfaces are in close contact. No particular consideration was given to the shape other than that.

[Problem that the invention seeks to solve]

In electron beam welding, since the amount of melting is small, even if the axis of the electron beam is slightly misaligned with respect to the groove surface, there is a high risk that a fused portion 51 as shown in FIG. 9 will occur.

Also, in 9 ferromagnetic materials.

Residual magnetism may cause local bending of the weld line, resulting in a fusion defect 52 as shown in FIG. 10. In Figures 9 and 10, 41.42 indicates the melting part, 18
．． 14 indicates the position of the original groove surface.

In this way, part of the groove surface remains as it is! The remaining fusion failure is a planar defect in shape and greatly affects the strength of the weld. Therefore, in electron beam welding, it is necessary to take precautions and precautions in the welding process to prevent the above-mentioned fusion defects from occurring.

Furthermore, after welding is completed, a non-destructive inspection must be performed to confirm that there are no surface defects of this kind and to guarantee the quality. However, the melted part.

Accompanied by contraction during solidification. Therefore, if a fusion defect remains in a part of the groove, the groove surfaces are brought into close contact with each other. therefore.

A typical smooth finished bevel profile will result in very closely spaced surface defects.

There are various non-destructive inspection methods, including those for surface defects with openings on the surface as shown in FIG.

Visual inspection, penetrant testing, etc. are used. Also, the first
As shown in Figure 0, radiographic testing, ultrasonic testing, etc. are applied to internal defects hidden inside, but any non-destructive testing method may be used.

It is difficult or disadvantageous to detect a pair of planar defects that are in close contact with each other.

Figure 11 is an experimental example regarding the detection limit of cracks in radiographic tests, and shows the procedure for sampling defects formed within the plate thickness from the radiation irradiation direction E. Figure 12 shows the gap between cracks F based on the experimental results. This indicates that the narrower g is, the deeper the crack F that can be detected becomes, while the shallower the crack F cannot be detected. Further, an example showing the relationship between surface pressure and echo height in an ultrasonic flaw detection test will be described later, and it is shown that the echo height decreases as the pressure increases. In other words, it becomes difficult to detect defects when the surfaces are in close contact with each other. Although an experimental example is not shown, there is a problem in that closely adhered surface defects have poor permeability and are difficult to detect not only by visual inspection but also by liquid penetrant testing.

Means for Solving Problem C] In order to solve the above-mentioned problems, the present invention aims to eliminate the high risk of defective fusion (due to misalignment) in electron beam welding, and to detect the defective fusion through non-destructive testing. The weld groove has a shape that prevents surface defects in close contact so that they can be easily and reliably discovered. In other words, the surface roughness of both sides or one side of the electron beam welding groove mating surface should be 25~25.
The present invention provides a groove shape for electron beam welding, which is characterized in that electron beam welding is performed with a groove shape finished in a range of 250 μm.

[Effect]

Since the groove shape for electron beam welding of the present invention has the groove shape as described above, even if poor fusion occurs due to the roughening of the groove mating surfaces, the surfaces will not come into close contact and a gap of about several tens of micrometers will be created. The groove shape is such that a fused portion can be easily and reliably detected by applying one of the non-destructive inspection methods or a combination thereof.

〔Example〕

Hereinafter, two embodiments of the present invention will be specifically described based on embodiments shown in the drawings. FIG. 1 is a sectional view showing a groove shape for electron beam welding according to an embodiment of the present invention.

FIG. 2 is a partially enlarged sectional view of the groove mating surface of FIG. 1 according to this embodiment. FIG. 3 is a cross-sectional view of an example in which only one of the groove mating surfaces according to this embodiment has a rough comb and the other is a smooth surface. FIG. 4 is a sectional view of a welded part in which the axis of the electron beam is inclined to the groove mating surface according to this embodiment. FIG. 5 is an enlarged cross-sectional view of a fusion failure caused by welding in the groove shape shown in FIG. 3 according to this embodiment.

FIG. 6 is a schematic diagram showing an experimental example of an ultrasonic flaw detection test according to this embodiment. FIG. 7 is a graph showing the experimental results of FIG. 6 according to this example. The explanation will be given below.

In FIG. 1, 11 and 12 are members to be welded.

lla and 12a are respective groove surfaces.

FIG. 2 shows the characteristics of the present invention. In this embodiment, both sides 11a and 12a of the groove surface are roughly finished.
A gap 81 exists when the groove surfaces are aligned. In FIG. 3, only the groove surface 11b is made rough, and a gap 32 exists as in FIG. 2. In addition.

In this example, the illustration of the entire groove surface is omitted. Also, in Figure 4, 4
5 indicates a welded portion, and 5 indicates a poorly fused portion. Figure 5 is the third
Perform welding under the groove conditions shown in the figure.

This is an enlarged view of a poorly fused portion, and the melted portion 4 shown in FIG. 4 contracts when solidified. Therefore, the unfused portion 5 is in a state in which nine surfaces are pressed together, as shown in FIG. 5. In other words, the roughly finished groove surface ob
The convex part is pressed, but the concave part does not fit tightly.

A gap 33 is left.

If there is a gap in the area of poor fusion, radiographic examination is performed.

Detection by non-destructive testing such as ultrasonic testing becomes easier. FIG. 6 is a schematic diagram showing an experimental example of an ultrasonic flaw detection test to demonstrate the effects of the present invention.

In this figure, 15 and 16 are test specimens, and 6 is an ultrasonic probe. In the experiment, test specimens 15 and 16 were brought into contact with each other at the surface 7, and the strength A of the reflected wave at the corner formed by 7 and 15 was measured while changing the pressure P. 7th
Among the experimental data shown in the figures, A shows the case where the surface roughness of the contact surface 7 is within the range of the present invention (about 50 μm), and B shows the case where the conventional general surface roughness is about 10 μm). As a result, 2. If the surface roughness is fine, the surfaces will be pressed together and there will be no gap, and the ultrasonic wave will pass through the core, weakening the reflected wave. 9. With the surface roughness of the present invention, it will be difficult to press. The presence of gaps makes it difficult for the strength of reflected waves to decrease. Therefore, if the surface roughness of the groove surface is kept within the range of the present invention, even if fusion failure occurs, the reflected waves will be effectively captured and detection will be facilitated.

Note that the roughness of the groove surface that exhibits the effect varies depending on the thickness, material, welding conditions, etc. of the welding member, but if it is less than 25 μm, there is no moderate effect. on the other hand.

If it is too rough, there is a high possibility that the quality of the weld will be adversely affected, such as large deformation after welding.
The groove shape has an upper limit of m.

〔Effect of the invention〕

As specifically explained above, in the present invention, by roughening the surface roughness of the image side or one side of the welding groove mating surface, even if fusion failure occurs, that surface will not be crimped and there will be a gap. It becomes a state with. Therefore, if it occurs on two surfaces, it can be easily and reliably discovered by visual inspection or liquid penetrant testing, and if it is hidden inside, it can be easily and reliably discovered by radiographic testing or ultrasonic testing.

Therefore, by performing these non-destructive tests after welding, the quality of the welded portion can be guaranteed.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing a groove shape for electron beam welding according to an embodiment of the present invention, and FIG. 2 is a partially enlarged cross-sectional view of the groove mating surface of FIG. 1 according to the present embodiment. FIG. 3 shows a rough comb on one side of the groove mating surface according to this embodiment;
The other is a cross-sectional view of an example with a smooth surface, FIG. 4 is a cross-sectional view of a welded part in which the axis of the electron beam is inclined to the groove mating surface according to this example, and FIG. 5 is a cross-sectional view of a welded part according to this example FIG. 3 is an enlarged cross-sectional view of a poorly fused portion due to groove-shaped welding shown in FIG. 3, and FIG. 6 is a schematic diagram showing an experimental example of an ultrasonic flaw detection test according to this embodiment. FIG. 7 is a graph showing the experimental results shown in FIG. 6 according to this example, FIG. 8 is a perspective view showing the groove shape of a flat plate for ordinary electron beam welding, and FIG. 9 is a graph for ordinary electron beam welding. Fig. 10 is a cross-sectional view of a welded part where the axis of the electron beam is tilted toward the groove mating surface. Fig. 11 is a schematic diagram of an experimental example of cracking in a normal electron beam welded part by radiation transmission testing.
FIG. 12 is a graph showing the relationship between the gap between normal internal cracks and the detectable crack depth. 1.2... Flat plate, 4... Melted part, 5... Poor fusion part. 6... Ultrasonic probe, 7... Groove surface, 11... Member, 11a... Groove surface, 12... Member, 12a...
・Groove surface, 18.14...Groove surface, 15.16・
...Test specimen, 81.82.83...Gap. 41.42... Melted part, 51.52... Poor fusion part.

Claims (1)

[Claims] A groove shape for electron beam welding, characterized in that electron beam welding is performed with the groove shape having a surface roughness of 25 to 250 μm on both sides or one side of the mating surfaces of the groove for electron beam welding.