• Title, Summary, Keyword: PTAW

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Characteristics of Microstructure of Hardfacing Layer of Stellite 6 with Mo Addition (몰리브덴을 첨가하여 PTAW법으로 육성된 Stellite 6합금의 미세조직 특성평가)

  • 신종철;김재수;이덕열;양재웅;윤진국;노대호;이종권
    • Journal of the Korean institute of surface engineering
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    • v.35 no.4
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    • pp.241-248
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    • 2002
  • Hardfacing layers of Stellite 6 alloy with different molybdenum content are deposited on AISI 1045 carbon steel using plasma transferred arc welding (PTAW). The properties of the hardfacing layer are investigated in order to clarify the effect of molybdenum addition to the cobalt-base alloy. With an increase in molybdenum contents, the size of Cr-rich carbides in the interdendritic region is abruptly refined, but volume fraction of the carbide slightly increases. Also, with an increase of Mo, $M_{6}$ C type carbides are formed instead of Cr-rich $M_{7}$ $C_{3}$ type carbided, and this microstructural change enhanced the mechanical properties of Stellite 6 alloy.

A Study on Formation of Thick Hardened Layer on Al Alloy Surface by PYAW Process (PTAW법에 의한 Al 합금 표면의 후막경화층 형성에 관한 연구)

  • 임병수;김봉수;오세훈;황선효;서창제
    • Journal of Welding and Joining
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    • v.15 no.5
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    • pp.92-103
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    • 1997
  • The purpose of this study is to improve the wear resistance and hardness of Al alloy by making a formation of the thick surface hardening layers. The thick surface hardening layers were formed by PTAW(Plasma Transferred Arc Welding), with the addition of metal powders (Cu), ceramics powders (NbC, TiC), and mixture powders (Cu+NbC) in Al alloy (A1050, A5083). Mechanical properties of overlaid layers (wear resistance, hardness) were investigated in relation to the microstructure. The results obtained are summarized as follows: The depth of penetration was increased with increasing powder feeding rate. It is considered that these increase were due to the thermal pinch effect by the addition of powders, especially, for the Cu powders, were due to the heat of reaction with the matrix. The hardness and wear resistance of overlaid layers were improved with increasing powder feeding rate. For the Cu powders, it is considered that these increase were due to the increase of the formation of ${\theta}(CuAl_2)$ phase with increasing feeding rate of Cu powers.

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A Study on Hot Ductility Behavior of Ni-based Superalloys (니켈기 초내열합금의 고온연성거동에 관한 연구)

  • Lee, Choung-Rae;Um, Sang-Ho;Kim, Sung-Wook;Choi, Cheol;Lee, Chang-Hee
    • Journal of Welding and Joining
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    • v.22 no.2
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    • pp.59-68
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    • 2004
  • Plasma transferred arc welding (PTAW) has been taken into consideration for repairing Ni-based superalloy components used gas turbine blades. Various cracks has been generally reported to be found in the base metal heat affected zone(HAZ) along grain boundary. Thus, hot cracking susceptibility of Ni-based superalloys was evaluated according to heat treatments. Hot ductility test was conducted on specimens with solution treated at 112$0^{\circ}C$ for 2 hours and aging treated at 845$^{\circ}C$ for 24hours after solution treatment. The results of the hot ductility test appeared that solution treated specimens were the highest ductility recovery rate among three conditions. The loss of ductility at high temperature in Ni-based superalloy was mainly controlled by the degree of pain boundary wetting due to constitutional liquation of MC carbide precipitates. Meanwhile, the highest ductility recovery rate in solution-treated alloys seems to be lack of M23C6, which can be dissolved during heating and then result in the local enrichment of Cr in the vicinity of the grain boundary.

Wear performance of Plasma Transferred Arc deposited layers

  • Yoon, Byoung-Hyun;Kim, Hyung-Jun;Lee, Chang-Hee
    • Proceedings of the KWS Conference
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    • pp.245-247
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    • 2001
  • In this study, the effects of dilution on the wear behavior of PTAW (Plasma Transferred Arc Welding) Inconel 625, Inconel 718 and Stellite 6 overlays on Nimonic 80A were investigated. Inorder to evaluate the wear performance, two-body and three-body abrasive wear test, and dry sliding wear test were performed. According to wear tests, the wear rate of deposit with dilution 30% was higher than that of dilution 10% by 10%, and it was also found the plastic deformation near worn surface.

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Trend of the welding process technology (고능률 용접프로세스의 발전동향)

  • Kim, H.T.;Kil, S.C.
    • Proceedings of the KAIS Fall Conference
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    • pp.653-655
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    • 2012
  • The increasing interest in the welding process technology is placing stringent demands on the manufacturing techniques and performance requirements, and the manufacture employs the high quality and efficiency welding process technology. This paper covers recent development trends of the welding process technology including the GTAW, PTAW, FSSW, etc.

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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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    • 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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