JPS6379060A - Method for ultrasonic flaw detection of fillet welded part - Google Patents

Abstract

PURPOSE:To enhance flaw detection capacity, by interposing a wedge wherein the angle formed by surface thereof is set to a proper one using two vertical probes for transmission and reception. CONSTITUTION:One surface of a wedge wherein the angle formed by two surface thereof is set to theta is placed on the welded bead 2 of a fillet welded part wherein the angle formed by the surface of a member 1 to be inspected where the presence of a planar flow 3 is estimated and the surface thereof is alpha. Herein, a contact medium is applied between the bead 2 and the wedge 4, Further, the angle theta of the wedge 4 is set by formula sintheta/sinalpha=va (the longitudinal wave speed in the wedge 4)/vb (the longitudinal wave speed in the bead 2) corresponding to the angle alpha of the bead 2. Then, the ultrasonic wave from a transmitting probe 5 is allowed to advance through the wedge 4 and the bead 2 to be allowed to vertically impinge against the flaw 3 and the reflected wave therefrom is received by a receiving probe 6 to detect the presence of the flaw 3. Therefore, a large reflected wave is returned from the flaw 3 in the vertical direction and the vertical direction and the effect of the multiple reflection wave in the wedge 4 is suppressed and even the small planar flow directly under the bead can be cen be certainly detected.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an ultrasonic flaw detection method for detecting planar defects occurring directly under a fillet weld.

[Conventional technology]

Thermal stress is applied directly below the weld bead in fillet welds during welding, so if there are laminations or non-metallic inclusions in the base material in this area, thermal stress may cause peeling, resulting in surface defects. . The presence of these planar defects significantly reduces the reliability of the weld, so their detection is important.

However, conventionally, there is no appropriate method for detecting surface defects directly under the weld bead of fillet welds. Only the planar defect 3 protruding from the bead 2 is detected using the vertical probe 5.

Therefore, the small surface defect B directly under the weld bead 2 cannot be detected, and the reliability of the structure having fillet welds is low.

[Problem that the invention seeks to solve]

The present invention was proposed in view of these circumstances, and
An object of the present invention is to provide an ultrasonic flaw detection method for fillet welds that can detect even small planar defects directly under the weld bead of fillet welds, thereby significantly improving the reliability of fillet welded structures. purpose.

[Means for solving problems]

For this purpose, the present invention sets the angle θ between the two faces of the wedge to the angle α between the surface of the weld bead of the fillet weld and the surface of the member to be inspected.
One side of the wedge set at an angle related to the longitudinal wave velocity ratio va/vb in the weld bead is in contact with the surface of the weld bead, and a pair of vertical transverse beams for transmission and reception are placed on the other side. A sonic probe is mounted, and the ultrasonic waves from the transmitting probe are propagated through the wedge and weld bead to perpendicularly hit the planar defect in the inspected member, and the reflected waves are transmitted to the receiving probe. It is characterized by reception using a feeler.

[For production]

Through the intervention of a wedge that sets the angle between the two faces at an appropriate angle,
The ultrasonic wave hits the planar defect perpendicularly, and a large reflected wave is returned from the planar defect, and by using two vertical probes, one for transmitting and one for receiving, This suppresses the effects of multiple reflected waves and synergistically increases defect detection ability.

〔Example〕

An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a partially sectional side view of an embodiment of the method of the present invention, and FIG. 2 is a plan view thereof.

In the above figure, the surface of the inspected member 1 where the existence of the surface defect B is presumed is located, and the weld bead 2 of the fillet weld where the angle between the two surfaces is α is θ. I'll post one side of 櫟4.

Of course, a couplant is applied between the weld bead 2 and the weld 4.

The angle .alpha. and the angle .theta. have the following relationship. Therefore, the angle .theta. of the wedge 4 is set according to the angle .alpha. of the weld bead 2.

Furthermore, two vertical ultrasonic probes 5 and 6 for transmission and reception are placed side by side on the surface of the wedge 4.

The ultrasonic waves from the transmitting probe 5 are made to travel through the wedge 4 and the welding bead 2 and perpendicularly hit the planar defect 3 in the inspected member 1, and the reflected waves are transferred to the receiving probe 6. The receiver detects the presence of defects. Therefore, a large reflected wave in the vertical direction is returned from the planar defect 3, and since the reflected wave is received by a receiving probe 6 different from the transmitting probe, the influence of multiple reflected waves within the wedge 4 is reduced. is suppressed, and even a small planar defect directly under the weld bead 2 can be reliably detected.

The detection sensitivity of this method is greatly increased, and in experiments, it was possible to detect planar defects of about 5 mi by using a highly viscous couplant without particularly finishing the surface of the weld bead by 4 degrees.

〔Effect of the invention〕

In short, according to the present invention, the angle θ between the two faces of the wedge is equal to the angle α between the surface of the weld bead of the fillet weld and the surface of the member to be inspected.
One side of the wedge, which is set at an angle related to the longitudinal wave velocity ratio va/vb during welding, is brought into contact with the surface of the weld bead. A pair of vertical ultrasonic probes is mounted, and the ultrasonic waves from the transmitting probe are propagated through the wedge and weld bead to perpendicularly hit the planar defect in the inspected member, and the reflected wave is detected. By receiving this with the above-mentioned receiving probe, it is possible to detect even small surface defects directly under the weld bead of fillet welds, thereby significantly improving the reliability of fillet welded structures. The present invention is industrially extremely useful because it provides an ultrasonic flaw detection method for fillet welds.

[Brief explanation of the drawing]

FIG. 1 is a partially sectional side view of an embodiment of the ultrasonic flaw detection method for a fillet weld according to the present invention, FIG. 2 is a plan view thereof, and FIG. 3 is a partially sectional side view of a conventional ultrasonic flaw detection method. DESCRIPTION OF SYMBOLS 1... Member to be inspected, 2... Weld bead, 6... Planar defect, 4... Cut, 5 t 6... Vertical ultrasonic probe. I/-Pi Japanese 26-m 10-meter +7'Cfr 1st
Figure 1.3 Figure 2 Figure 3

Claims (1)

[Claims] The angle θ formed by the two faces of the wedge is defined as the angle α between the surface of the weld bead of the fillet weld and the surface of the inspected member, the wedge, and the longitudinal wave velocity ratio va/vb in the weld bead. One side of the wedge set at a related angle is brought into contact with the surface of the weld bead, and a pair of vertical ultrasonic probes for transmitting and receiving is placed on the other side, and a pair of vertical ultrasonic probes for transmitting and receiving are placed on the other side. A method for ultrasonic fillet welds, characterized in that ultrasonic waves are made to travel through the wedge and the weld bead to perpendicularly hit the planar defects in the member to be inspected, and the reflected waves are received by the receiving probe. Sonic flaw detection method.