Evident LogoOlympus Logo
자료실
Application Notes
자료로 돌아가기

마찰 교반 용접부 위상 배열 검사


Background:

The friction stir welding (FSW) technique was developed as a method to join materials that are difficult to fusion weld such as aluminum alloys. The quality of the weld obtained is very high and the material structure is uniform. However, the process may generate small, tight defects that are hard to detect.

Friction stir welding is a welding process unlike most others in that there is no liquid state weld pool. As such, the potential defects in the weld are quite different. The defects present in such welds are typically lack of penetration, worm holes, porosity and kissing bonds. This last defect type is formed by a thin oxide layer which prevents fusion of the material despite being in contact. Furthermore, due to the weld process, defects can be orientated in any direction. The weld “cap” can be quite rough following this inspection technique and it is typically not optimal to use standard Rexolite wedges.

The best method for inspecting friction stir welds is ultrasonic phased array testing using a water-coupled wedge. Because of the weld shape, raster scanning is not practical, but with phased arrays, inspection of the entire weld volume can be done in a single-pass scan. Phased arrays also permit lateral scanning to detect transverse defects. Optimization of the inspection angle maximizes the probability of detection. The increased number of zones covered by phased arrays provides accurate flaw sizing and location. High speed, accuracy, and versatility make phased arrays the choice technique for FSW inspection.

Equipment

The equipment used for the inspection is comprised of:

OmniScan SX, MX2 16:64 or 16:128 Phased Array Unit
FOCUS PX Acquisition Unit
10L64-FSW PA probe
Normal and Lateral water wedges (SFSW-N45S-WHC and SFSW-L45S-WHC)
1 Wing Scanner, VersaMouse or mini-wheel encoder
1 water pump

inspection set up
Inspection setup

irrigated probeirrigated probe

Typical irrigated wedges

Typical Procedure

As defects can be orientated in any direction, a single pass inspection is typically not sufficient to detect all defects with an adequate signal-to-noise ratio. As such, the weld would typically be inspected in the 90° direction with the N45S wedge and in the 0° direction with the L45S wedge.

probe position 90probe position 0

Probe positioning for normal (90°) and lateral (0°) scans

The first pass utilizes a linear 45° scan from the normal (90°) direction. A guide can be used to maintain a constant index offset of the probe with respect to the weld along the entire weld line. A position encoder can be attached to the probe to provide a positional reference to scans. In the case of thinner welds a single pass will cover both the weld root and crown. For thicker parts, two passes at different offsets are necessary to obtain full volumetric coverage of the weld zone.

Wedge delay and material velocity are calibrated to obtain relevant skip overlap indications (B0 and T1 in the figure below). Gate A (red) was used to obtain the C-scan. This gate commenced prior to the end of the first skip (B0) and ended after the second skip (T1).

weld delay

This S-scan image shows notches representing root defects at each extremity of a weld, both appearing in the first leg (reference B0). The probe position allows for entire width of the weld to be inspected simultaneously.

The process is then repeated from the transverse (0°) direction. A similar guide can be used to center the probe along the weld with the probe aligned at 0° to the weld line. A linear scan is acquired by pulling the probe along the weld. C-scans can be generated by placing the gate in between the front wall noise and the significant noise originating from the top surface after one full skip. The corner trap echo from the cracks on the root surface will hit maximum amplitude in the middle of the gate. The corner trap echo from the cracks from the crown will hit a maximum outside the gate in the noisy region. However, these defects can be mapped due to the tip echoes which fall within the gate.

S-Scan

This S-scan shows the corner trap echo and tip crack echo of a transverse notch on the surface of a weld. The red gate (A) begins just after the noise originating from the front wall and ends just before the noise originating from the top surface after one full skip.

Results

A reference block containing numerous axial and transverse notches as shown below was scanned as described above. As seen in the following C-scan images, the two inspection approaches provided clear indications from all notches that were oriented either parallel or perpendicular to the weld line. Reference notches oriented at 45° to the weld line present more of a challenge. The detection capability in this case depends on the depth and length of the notch. In order to increase the detectability of these defects, additional scans can be performed with the phased array probe skewed at plus and minus 45° from the straight line orientation. This would clearly increase the reflection amplitude from the 45° notches.


C-scan stir weld
C-scan image from normal incidence scan, showing reflectors aligned along weld axis.

Transverse c-scan

C-scan image from transverse scan, showing reflectors aligned with perpendicular to weld axis.

After the scan has been captured, each indication can be reviewed by selecting a location on the scan via cursors. The captured A-scan at that location can then be displayed as seen below.

Conclusion

Pulse echo inspections of friction stir welds can detect all volumetric-type defects such as cracking, incomplete penetration, and lack of fusion. Transverse defects can be detected using lateral scans. Phased array testing offers the advantages of optimizing inspections by providing focusing and refraction angle selection, as well as providing faster inspections by providing greater coverage in a single pass than a single element angle beam.

 

Olympus IMS

이 애플리케이션에 사용되는 제품
이 새로운 소프트웨어는 옴니스캔 데이터 분석을 위한 가장 효율적이고 저렴한 선택으로, 옴니스캔 온보드 소프트웨어에 제공되는 것과 동일한 분석 도구를 갖추고 있으며, 개인용 컴퓨터에서 실행할 수 있는 유연성이 더해졌습니다.
VersaMOUSE™는 위상 배열 프로브를 사용해 선형 인코딩 스캔을 수행하도록 설계된 스캐너입니다. 통합 인덱싱 버튼은 CFRP 평면 패널 및 부식 검사와 같은 2D 매핑 응용에 이상적입니다. VersaMOUSE는 인코딩된 1라인 스캔을 수행한 다음 수직 방향으로 위치를 인덱싱할 수 있습니다. 그런 다음 다른 1라인 스캔을 수행해서 이전 스캔과 나란히 배치시킬 수 있습니다.. 이 과정을 반복해서 관심 영역에 대한 완전한 2D지도를 생성시킬 수 있습니다.
단일 그룹인 경량 옴니스캔 SX는 읽기 쉬운 8.4인치(21.3cm) 터치 스크린을 갖추고 있으며, 비용 효율적인 솔루션을 제공합니다. 옴니스캔 SX는 SX PA와 SX UT의 두 가지 모델로 제공됩니다. SX PA는 UT 전용 SX UT와 마찬가지로 P/E, P-C 또는 TOFD 검사를 위한 재래식 UT 채널을 장착한 16:64PR 장치입니다.
옴니스캔 MX2는 이제 UT 채널이 있는 새로운 위상 배열 모듈(PA2), TOFD(회절 비행 시간)에 사용할 수 있는 새로운 2채널 재래식 초음파 모듈(UT2) 및 성공적인 옴니스캔 MX2 플랫폼의 기능을 확장하는 새로운 소프트웨어 프로그램을 제공합니다.

확장 가능한 FOCUS PX 획득 장치와 FocusPC 소프트웨어에는 최신 위상 배열 및 기존 UT 기술이 포함되어 있어 자동화 및 반자동화된 시스템에 쉽게 통합됩니다. C-스캔과 A-스캔 원시 데이터를 생성하고 저장하는 FOCUS PX 및 자체 소프트웨어의 기능 덕분에 이 제품은 검사 후 데이터 분석에 기반하여 검사 결과가 나오는 응용 분야에 가장 적합합니다. 예를 들면 항공우주 산업(복합 적층판), 발전(풍력 블레이드), 수송(차륜), 금속(단조 부품) 등의 분야가 여기에 속합니다.

옵션형 FocusControl, FocusData 및 OpenView 소프트웨어 개발 키트(SDK)는 FOCUS PX 장치와 호환되므로 고객은 자체 응용 프로그램애플리케이션 소프트웨어를 개발할 수 있습니다.

위상 배열 응용 분야별 프로브의 범위는 0.5MHz에서 18MHz이며, 16, 32, 64 또는 128개의 소자가 있을 수 있습니다. 특수 프로브는 최대 수백 개의 소자를 가지고 있을 수 있습니다.
죄송합니다. 이 페이지는 해당 국가에서 사용할 수 없습니다.
아래 양식을 작성하여 원하는 내용을 알려주십시오.
죄송합니다. 이 페이지는 해당 국가에서 사용할 수 없습니다.