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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.
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,임만배,이상필,윤한기,오세규,Kong, Yu-Sik,Lim, Man-Bae,Lee, Sang-Pill,Yoon, Han-Ki,Oh, Sae-Kyoo 대한기계학회 2002 大韓機械學會論文集A Vol.26 No.6
The high temperature creep behavior of heat machine systems such as aircraft engines, boilers and turbines in power plants and nuclear reactor components have been considered as an important and needful fact. There are considerable research results available for the design of high temperature tube materials in power plants. However, few studies on the Initial Strain Method (ISM) capable of securing repair, maintenance, cost loss and life loss have been made. In this method, 3 long time prediction Of high temperature creep characteristics can be dramatically induced through a short time experiment. The purpose of present study is to investigate the high temperature creep lift of Udimet 720, SCM 440-STD61 and 1Cr-0.5Mo steel using the ISM. The creep test was performed at 40$0^{\circ}C$ to $700^{\circ}C$ under a pure loading. In the prediction of creep life for each materials, the equation of ISM was superior of Larson-Miller Parameter(LMP). Especially, the long time prediction of creep life was identified to improve the reliability.