• Title/Summary/Keyword: Plasma transferred arc(PTA) process

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Improvement of Wear Resistance and Formation of Si Alloyed Layer on Aluminum Alloy by PTA Process (PTA법에 의한 Al 합금표면의 Si 합금층 형성과 내마모성 개선)

  • ;;松田福久;中田一博
    • Journal of Welding and Joining
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    • v.15 no.5
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    • pp.134-143
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    • 1997
  • The formation of thick alloyed layer with high Si content have been investigated on the surface of Al alloy (A5083) plate by PTA process with Si powder. Hardening characteristics and wear resistance of alloyed layer was examined in relation to the microstructure of alloyed layer. Thick hardened layer in mm-order thickness on the surface of A5083 plate can be formed by PTA process with wide range of process condition by using Si powder as alloying element because of eutectic reaction of Al-Si binary alloy. High temperature and rapid solidification rate of molten pool, which are features of PTA process, enable the formation of high Si content alloyed layer with uniform distribution of fine primary Si paticle. High plasma arc current was beneficial to make the alloyed layer with smooth surface appearance in wide range of powder feeding rate, because enough volume of molten pool was necessary make alloyed layer. Uniform dispersion of fine primary Si particle with about 30${\mu}{\textrm}{m}$ in particle size can be obtained in layer with Si content ranging from 30 to 50 mass %. Hardness of alloyed layer increased with increasing Si content, but increasing rate of hardness differed with macrostructure of alloyed layer. Wear resistance of alloyed layer depended on $V_{si}$(volume fraction of primary Si) and was remarkably improved to two times of base metal at 20-30% $V_{si}$ without cracking, but no more improvement was obtained at larger $V_{si}$.

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A Study on the Abrasive Wear Properties of the PTA Overlay Layers using the Super Alloy Powder (초내열합금분말에 의한 PTA 오버레이부의 연삭 마모 특성 연구)

  • Kim, Young-Sik;Choi, Young-Gook;Lim, Chang-Hoon;Kim, Jong-Do
    • Journal of Welding and Joining
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    • v.27 no.3
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    • pp.80-84
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    • 2009
  • The Plasma Transferred Arc (PTA) overlay welding method is lately introduced as one of the most useful surface overlay method of the engine component. In this paper, the overlay welding on the SNCrW heat resisting alloy was conducted by the PTA overlay welding process using the super alloy powder. The characteristics of the overlay layers were investigated through the metallurgical and abrasive test. Experimental results showed that the overlay on the SNCrW heat resisting alloy surface was successfully made without hot cracking. The friction wear characteristics of the Co-base Stellite 6 overlayer were most superior. However the abrasive wear characteristics were most inferior in the Co-base Stellite 6 overlayer.

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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A Study on Characterization of Modified Surface Manufactured by PTA Spray (PTA 용사에 의해 제조된 표면개질부의 특성에 관한 연구)

  • Kim, Gwang-Soo;Ji, Jung-Hoon
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.6 no.2
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    • pp.110-115
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    • 2005
  • Plasma Transferred Arc Spray process was used to make modified surface for wear and corrosion resistant by using Co system powder type alloy. The modified surface was produced by changing only spray current and other process variables were constant. The current range was from 80 amp to 140 amp as inclosing 20 amp. It was appeared that the geometrical shape, microstructures and microhardness of the modified surface were affected by the different cooling rate of base metal. The modified surface that produced by 120 amp current exhibited the fine microstructure and the highest microhardness number impling good surface characteristics. It was also found that the spray current affected the width but not the height of the bead as increasing current.

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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.

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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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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Comparison of clad layer characteristics with overlapping criterion in multi pass laser cladding (멀티패스 레이저 클래딩에 있어서 중첩률의 기준에 따른 클래드 층의 특성 비교)

  • Kim, Jong-Do;Lee, Eun-Jin;Whang, Jun-Gu
    • Journal of Advanced Marine Engineering and Technology
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    • v.40 no.9
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    • pp.768-773
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    • 2016
  • Engine valve seat and face, which are the important factors affecting engine performance, are required to have wear, heat and corrosion resistance. In order to produce surface layer with these characteristics, PTA(plasma transferred arc) surfacing procedure is generally employed, but problems, such as large HAZ and high dilution etc., frequently occurr. Laser cladding, which overcomes the drawbacks of conventional technologies, can be employed to create a superior clad layer with low dilution, small heat affected zone, and minimal distortion. However, in case cladding is to be applied to a large area, it is necessary to overlap 1 pass clad layer because of limited clad layer width. Two criteria for the overlapping ratio-beam size and clad layer width-have been considered thus far. Upon inspection of multi pass clads, produced by different overlapping criteria, it was observed that the greater the increase in overlapping ratio, the greater was the decrease in clad layer width and increase in clad layer height regardless of the criterion used. However, a multi pass clad overlapped by the beam size criterion demonstrated a higher hardness value than a clad overlapped by the clad layer width owing to decreasing dilution of the substrate. In conclusion, the beam size was defined as the criterion for the overlapping, because the clad layer width increased or decreased depending upon process parameters.