http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Dissimilar welding between Ti–6Al–4V and 17-4PH stainless steel using a vanadium interlayer
Adomako, Nana Kwabena,Kim, Jeng O.,Lee, Se Hwan,Noh, Kyung-Ho,Kim, Jeoung Han Elsevier 2018 Materials science & engineering. properties, micro Vol.732 No.-
<P><B>Abstract</B></P> <P>In this study, electron beam welding, continuous laser welding, and pulsed laser welding were used to join Ti–6Al–4V alloy and 17-4PH stainless steel with a 1 mm pure V sheet interlayer. In addition, the effect of V composition on the mechanical properties of the welded joint by shifting the laser towards the 17-4PH was examined. Vanadium bonded well with Ti, and the weld metal was characterized by a (βTi,V) solid solution. In the V–steel welded joint, similar phases ((Fe,V)ss) but with different compositions were found in the MZs, which affected the mechanical properties. The cracked region was visible at the V–steel interface of the pulsed-laser-welded joint and contributed to its low tensile strength. Electron beam welding showed a good intact joint with no defects, and failure occurred in the vanadium interlayer. A common MZ was created for the three metals in EB1, which formed Fe<SUB>2</SUB>Ti and FeTi intermetallic compounds that acted as crack initiation sites and led to the failure of the welded joint during machine processing. Variation in V composition had a significant impact on the mechanical properties of the welded joints. Hardness increased incrementally with the V concentration, and joints with a composition of less than 35 at% V, which corresponded to α-Fe + (Fe,V)σ and α-Fe phase formation ranges, had better tensile properties than those with more than 35 at% V, which corresponded to the single (Fe,V)σ phase. However, care should be taken in regulating the laser beam in order to avoid a very low V content, since this could lead to the formation of unfused regions.</P>
RF 플라즈마를 이용한 순수 바나늄 분말의 구상화 거동 연구
Nana Kwabena Adomako,양승민,이민규,N. S. Reddyd,김정한 한국분말야금학회 2019 한국분말재료학회지 (KPMI) Vol.26 No.4
In the present work, spheroidization of angular vanadium powders using a radio frequency (RF) thermal plasma process is investigated. Initially, angular vanadium powders are spheroidized successfully at an average particle size of 100 μm using the RF-plasma process. It is difficult to avoid oxide layer formation on the surface of vanadium powder during the RF-plasma process. Titanium/vanadium/stainless steel functionally graded materials are manufactured with vanadium as the interlayer. Vanadium intermediate layers are deposited using both angular and spheroidized vanadium powders. Then, 17-4PH stainless steel is successfully deposited on the vanadium interlayer made from the angular powder. However, on the surface of the vanadium interlayer made from the spheroidized powder, delamination of 17-4PH occurs during deposition. The main cause of this phenomenon is presumed to be the high thickness of the vanadium interlayer and the relatively high level of surface oxidation of the interlayer.
중엔트로피 합금 기지 위에 적층조형된 스테인리스강과 타이타늄 합금의 접합특성 분석
박찬웅,이민규,김정한,Park, Chan Woong,Adomako, Nana Kwabena,Lee, Min Gyu,Kim, Jeoung Han 한국분말야금학회 2019 한국분말재료학회지 (KPMI) Vol.26 No.4
Additive manufacturing (AM) is a highly innovative method for joining dissimilar materials for industrial applications. In the present work, AM of STS630 and Ti-6Al-4V powder alloys on medium entropy alloys (MEAs) NiCrCo and NiCrCoMn is studied. The STS630 and Ti64 powders are deposited on the MEAs. Joint delamination and cracks are observed after the deposition of Ti64 on the MEAs, whereas the deposition of STS630 on the MEAs is successful, without any cracks and joint delamination. The microstructure around the fusion zone interface is characterized by scanning electron microscopy and X-ray diffraction. Intermetallic compounds are formed at the interfacial regions of MEA-Ti64 samples. In addition, Vicker's hardness value increased dramatically at the joint interface between MEAs and Ti-6Al-4V compared to that between MEAs and STS630. This result is attributed to the brittle nature of the joint, which can lead to a decrease in the joint strength.