• Title/Summary/Keyword: PTA process

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The Hardfacing Technology by PTA Overlaying Process (PTA 오버레이 공정을 이용한 산업설비부품의 표면경화기술)

  • Kil, S.C.;Kim, H.T.;Kim, S.W.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2009.10a
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    • pp.358-361
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    • 2009
  • The increasing interest in the surface modification technology by the plasma transferred arc overlaying process in the material processing is placing stringent demands on the manufacturing techniques and performance requirements, and the manufacture employs the high quality and efficiency plasma transferred arc overlaying technology. This paper covers recent technical trends of plasma transferred arc overlaying technology including the COMPENDEX DB analysis.

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Measurement of the Wear Amount of WC-coated Excavator Spacer using the PTA Process to Improve Wear Resistance by Using Reflective Digital Holography (반사형 디지털 홀로그래피를 이용한 내마모성 향상을 위한 공법이 적용된 PTA 굴착기의 초경 코팅 스페이서의 마모량 측정)

  • Shin, Ju-Yeop;Lim, Hyeong-Jong;Lee, Hang-Seo;Kim, Han-Sub;Jung, Hyun-Chul;Kim, Kyeong-suk
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.19 no.1
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    • pp.19-28
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    • 2020
  • The spacer, which is located between the bucket and the arm of an excavator, has a role in preventing damage to the excavator arm during excavation work. When the durability of the spacer is increased, the lifetime of the arm can be extended and the processing costs can be reduced. To increase the durability of the spacer, tungsten carbide (WC) coating was applied on the surface of a spacer using the plasma transferred arc (PTA) process. The confirm the durability, a wear test using a pin-on disk type of wear testing machine was done under the given conditions and the wear amount on the surface of a tested specimen was measured using reflective digital holography. The results were compared with that of ALPHA-STEP.

Hardening Characteristics of Aluminum Alloy Surface by PTA Overlaying with Metal Powders (I) (플라즈마분체 오버레이법에 의한 알루미늄합금 표면의 경화특성에 관한 연구(I) -후막 표면 합금화층의 형성조건과 그 조직-)

  • ;中田一博;;;松田福久
    • Journal of Welding and Joining
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    • v.12 no.4
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    • pp.85-101
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    • 1994
  • Effect of Cr, Cu and Ni metal powders addition on the alloyed layer of aluminum alloy (AC2B) has been investigated with the plasma transferred arc (PTA) overlaying process. The overlaying conditions were 125-200A in plasma arc current, 150mm/min in process speed and 5-20g/min in powder feeding rate. Main results obtained are summarized as follows: 1) It was made clear that formation of thick surface alloyed layer on aluminum alloy is possible by PTA overlaying process. 2) The range of optimum alloying conditions were much wider in case of Cu and Ni powder additions than the case of Cr powder addition judging from the surface appearance and the bead macrostructure. 3) Alloyed layer with Cu showed almost the homogeneous microstructure through the whole layer by eutectic reaction. alloyed layers with Cr and Ni showed needle-like and agglomerated microstructures, the structure of which has compound layer in upper zone of bead by peritectic and eutectic-peritectic reactions, respectively. 4) Microconstituents of the alloyed layer were analyzed as A1+CrA $l_{7}$ eutectics, C $r_{2}$al sub 11/, CrA $l_{4}$, C $r_{4}$A $l_{9}$ and C $r_{5}$A $l_{*}$ 8/ for Cr addition, Al+CuA $l_{2}$(.theta.) eutectics and .theta. for Cu addition, and Al+NiA $l_{3}$ eutectics. NiA $l_{3}$, N $i_{2}$A $l_{3}$ and NiAl for Ni addition. 5) Concerning defect of the alloyed layer, many blow holes were seen in Cr and Ni additions although there was lesser in Cu addition. Residual gas contents in blow hole for Cu and Ni alloyed layer were confirmed as mainly $H_{2}$ and a littie of $N_{2}$ Cracking was observed in compound zone of the alloyed layer in case of Cr and Ni addition but not in Cu alloyed layer.r.r.

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The Effect of Current and Preheat Temperature on Structure and Hardness of Stellite 12 Alloy Overlayer by PTA Process (PTA법에 의한 스텔라이트 12 합금 육성층의 조직과 경도에 미치는 전류와 예열온도의 영향)

  • Jung, B.H.;Kim, M.G.;Kim, G.D.;Kim, M.Y.;Lee, S.Y.
    • Journal of the Korean Society for Heat Treatment
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    • v.13 no.4
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    • pp.246-252
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    • 2000
  • Stellite 12 alloy-powder was overlaid on 410 stainless steel valve seat using plasma transferred arc(PTA) process. Variation of characteristic of microstructure and hardness of deposit with current(90~150 A) and preheat temperature(R.T.~$400^{\circ}C$) was investigated. Important conclusion obtained are as follows; All welding conditions used produced a sound deposit layer with no defect in single pass welding. The maximum deposit had 4.0~4.8 mm in thickness and its bead width was increased with increase of current and preheat temperature. The deposit showed hypoeutectic microstruture, which was consisting of primary cobalt dendrite and networked $M_7C_3$ type eutectic carbides. The amount of eutectic carbides was decreased and its dendritic secondary arm spacing was increased with increase of current. Hardness of the deposit was decreased with increase of current. Preheat temperature up to $400^{\circ}C$, however, showed little influence on the hardness and microstructure. The hardness was also influenced by diluted Fe content near the interface in addition to microstructure and dendritic secondary arm spacing. Hot hardness at $500^{\circ}C$ showed higher than 300 HV.

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Formation of Ti and Ti ceramics composite layer on aluminium alloy (Ti 및 Ti계 세라믹스에 의한 Al합금의 표면복합합금화)

  • ;;;松田福久;中田一博
    • Journal of Welding and Joining
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    • v.13 no.1
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    • pp.103-114
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    • 1995
  • Plasma Transferred arc(PTA) hard facing process has been developed to obtain an overlay weld metal having excellent wear resistance. The effect of Ti, TiSi$_{2}$ and TiC powders addition on the surface of Aluminum alloy 5083 has been investigated with PTA process. This paper describes the result of test the performance of the overlay weld metal. The result can be summarized as follows 1. Intermetallic compound is formed on surface of base metal in Ti or TiSi$_{2}$ powder but the reaction with surface of base metal is little seen in TiC powder. 2. In formation of composite layer on aluminum alloy surface by plasma transferred arc welding process, high melting ceramics like TiC powder is excellent. 3. The multipass welding process is available for formation of high density of powder. But the more number of pass, the less effect of powder, it is considered, and limits of number of pass. 4. By increasing area fraction of TiC powder on Al alloy surface, in especially TiC powder the hardness increase more than 40% area fraction and 88% shows about Hv 700.

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A Study on Relationship between Hot Ductility Behavior and Hot Cracking Susceptibility in PTA Weld of Ni-based Superalloy (니켈기 초내열합금 PTA용접부의 고온균열감수성과 고온연성거동에 관한 연구)

  • Lee, Chung-Rae;Kim, Sung-Wook;Choi, Woo-Hyuk;Eom, Sang-Ho;Lee, Chang-Hee;Kim, Jae-Chul;Choi, Chul
    • Proceedings of the KWS Conference
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    • 2003.05a
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    • pp.40-42
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    • 2003
  • In general, nickel-base superalloy has been extensively used as land-based gas turbine blades and vanes. Plasma transferred arc welding(PTAW) has been considered as a repair welding process of nickel-base superalloy. This research evaluated the relationship between hot ductility behavior and hot cracking susceptibility in nickel-base superalloys. Ductility recovery rate of nickel base superalloys was found to be poor due to incipient melting and constitutional liquation. This seems to increase the hot cracking susceptibility.

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Hardening Characteristics of Aluminum Alloy Surface by PTA Overlaying with Metal Powders (II) -Hardening charactersteristics and wear resistance of thicker surface alloyed layer- (플라즈마분체 오버레이법에 의한 알루미늄합금 표면의 경화특성에 관한 연구( II ) -후막 표면 합금화층의 경화특성과 내마모성-)

  • ;中田一博;;;松田福久
    • Journal of Welding and Joining
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    • v.12 no.4
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    • pp.102-109
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    • 1994
  • The thick and hard alloyed layer was formed on the surface of Aluminum Cast Alloy(AC2B) by PTA overlaying process with Cr, Cu and Ni metal powders under the condition of overlaying current 150A, overlaying speed 150mm/min and different powder feeding rate 5-20g/min. The characteristics of hardening and were resistance of alloyed layer have been investigated in relation to microstructure of alloyed layer. As a result, it was made clear that Cu powder was the most superier one in three metal powders used due to an uniform hardness distribution of Hv 250-350, good wear resistance and freedom from cracking in alloyed layer of which microstructure consisted of hypereutectic. On the contrary, irregular hardness distribution was usually obtained in Cr or Ni alloyed layers of which hardness was increased as Cr or Ni contents and reached to maximum hardness of about Hv 400-850 at about 60wt% Cr or 40wt% Ni in alloyed layer. However the cracking occurred in these alloyed layers with higher hardness than Hv 250-300 at more than 20-25wt% of Cr or Ni contents in alloyed layer. Wear rate of alloyed layer was decreased to 1/10 in Cu alloyed layer and 1/5 or 1/3 in Cr or Ni alloyed layer with same hardness of about Hv 300 in comparison with that of base metal at higher sliding speed.

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KSLV 추진기관 종합시험설비 피해 사고 예측 모델 해석

  • Lee, Jung-Ho;Kang, Sun-Il;Yu, Byung-Il;Kim, Yong-Wook;Cho, Sang-Yeon;Oh, Seung-Hyub
    • Aerospace Engineering and Technology
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    • v.4 no.2
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    • pp.163-170
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    • 2005
  • According to the KSLV program of KARI, it is planed to develop various launch vehicle and satellite 10 years hereafter. Large-scale test facilities, such as ReTF and PTA-II, are needed to fulfill this launch vehicle/satellite development project. The authors intend to arrange and describe various indexes that are needed in test facility design, construction and operation process. This technical paper is describing model analysis of damage prediction of accident in KSLV Integrated Propulsion System Test Facility based on propellant storage quantity and layout. In addition, the result can be used to produce safer design of test facility.

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Formation of Thicker Hard Alloy Layer on Surface of Aluminum Alloy by PTA Overlaying with Metal Powder (알루미늄 합금의 표면경화)

  • Lee, Young-Ho
    • Proceedings of the KWS Conference
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    • 1996.10a
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    • pp.3-15
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    • 1996
  • The formation of a thicker hard alloyed layer have been investigated on the surface of aluminum cast alloy (AC2B) by PTA overlaying process with Cr, Cu and Ni motel powders under the condition of overlaying current 125-200A. overlaying speed 150 mm/min and different powder feeding rate 5-20 g/min. In addition the characteristics of hardening and wear resistance of alloyed layer here been examined in relation to the microstructure of alloyed layer. Main results obtained were summarized as follows: 1) There was an optimum overlaying condition to get a good alloyed layer with smooth surface. This good layer became easy to be formed as increasing overlaying current and decreasing powder feeding rate under a constant overlaying speed. 2) Cu powder was the most superior one in metal powders used due to a wide optimum overlaying condition range, uniform hardness distribution of Hv250-350, good oar resistance and freedom from cracking in alloyed layer with fine hyper-eutectic structure. 3) On the contrary, irregular hardness distribution was usually obtained in Cr ar Ni alloyed layers of which hardness was increased as Cr or Ni contents and reached to maximum hardness of about Hv400-850 at about 60wt%cr or 40wt%Ni in alloyed layer. 4) Cracking occurred in Cr or Ni alloyed layers with higher hardness than Hv250-300 at mere than 20-25wt% of Cr or Ni contents in alloyed layer. Porosity was observed in all alloyed layers but decreased by usage of spherical powder with smooth surface.

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Effect of Cu-Additions on the Hand-Over Layer of an Aluminum Alloy - Hardening for the Top Ring Groove of Automotive Piston by the Plasma Transferred Arc Welding Process -

  • Moon, J.H.;Seo, C.J.;Hwang, S.H.
    • International Journal of Korean Welding Society
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    • v.1 no.1
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    • pp.58-62
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    • 2001
  • The surface of AC8A Ah alloy was modified by adding the Cu powder using a Plasma Transferred Arc (PTA) welding process. Under the optimum fabricating conditions, the modified surface of AC8A Ah alloy was observed to possess the sound microstructure with a minimum porosity. Hardness and wear resistance properties of the as-fabricated alloy were compared with those of the 76 heat-treated one. In case of the as-fabricated alloy, the hardness of the modified layer was twice that of the matrix region. Although significant increase in the hardness of the matrix region was observed after T6 heat treatment, the hardness of the modified layer was not observed to change. The wear resistance of the modified layer was significantly increased compared to that of the matrix region. The microstructure of a weld zone and the matrix region were investigated using the optical microscope, scanning electron microscope (SEM), electron probe microanalysis (EPMA), and transmission electron microscope (TEM). The primary and eutectic silicon in the weld zone were finer and more curved than in the matrix region, while some precipitates has had been found therein. According to the TEM observation, the predominant precipitate present in the weld zone was the $\theta$'phase, which is precipitated during cooling by rapid solidification in PTA welding process. Improvement of hardness and wear properties in the weld zone in the as-fabricated condition can be explained based on the presence of $\theta$’precipitates and fine primary and eutectic silicon distribution.

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