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이종마찰용접재의 최적용접조건과 음향방출에 의한 실시간 품질평가
공유식,이진경 한국산업융합학회 2019 한국산업융합학회 논문집 Vol.22 No.2
In this paper, dissimilar friction welding were produced using 15 mm diameter solid bar in chrome molybedenum steel(SCM440) to stainless steel(STS316L) to investigate their mechanical properties. Consequently, optimal welding conditions were n=2000 rpm, HP=70 MPa, UP=140 MPa, HT=10 sec and UT=10 sec when the metal loss(Mo) is 8.6 mm. In addition, an acoustic emission technique was applied to evaluate the optimal friction welding condition. AE parameters including the cumulative count, amplitude and energy showed a various changes according to the friction condition. A continuous type waveforms and low frequency spectrum was presented in friction time. On the other hand, a burst type waveform and high frequency spectrum was exhibited in pressing time.
공유식,곽재섭,강대민,김태완 한국정밀공학회 2013 International Journal of Precision Engineering and Vol. No.
This study aimed to devise the new method for tensile strength online prediction by using the acoustic emission signals in friction welding process. To verify the effect of operation parameters on the tensile strength of friction welded joints, Taguchi's method was used at experimental and analysis results. From the acoustic emission signals measured in the friction welding of Al6061 aluminum alloy material, the dimensionless coefficient, which consisted of root mean square and variance of signals, was defined. The tensile strength prediction model was developed with the dimensionless coefficient and then the online prediction on tensile strength of friction welded joints was conducted. The process parameters of heating pressure and heating time dominantly affected the tensile strength of friction welded joints. At the study result, the tensile strength online prediction by using acoustic emission signals was the useful and accurate method for friction welded joints of the Al6061 aluminum alloy material.
후열처리에 따른 A105/A312 배관재의 이종 마찰용접 최적화
공유식,박영환 대한용접접합학회 2019 대한용접·접합학회지 Vol.37 No.2
A study on dissimilar friction welded joints were performed using 22 mm diameter tube-to-bar in forging bar steel(ASTM A105) to stainless pipe steel(ASTM A312) for piping materials. The main friction welding parameters were selected to endure good quality welds on the basis of visual examination, tensile tests, Virkers hardness surveys of the bond of area and HAZ, and macrostructure investigations. The specimens were tested as-welded and post-weld heat treated(PWHT). The tensile strength of the friction welded joints was increased up to 100 % of the A105 base metal under the condition of heating time(HT). Optimal welding conditions were n=2,000 rpm, HP=50 MPa, UP=100 MPa, HT=5 sec and UT=10 sec when the total metal loss(Mo) is 11 mm. The peak of hardness distribution of the friction welded joints can be eliminated by PWHT. Two different kinds of materials are strongly mixed to show a well-combined structure of macroparticles without any molten material and particle growth or any defects. In addition, the results of the radiological examination(RT) showed that there was no blowhole in the friction welding area.