• Title/Summary/Keyword: 스텔라이트

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The Effect of Current on Characteristics of Stellite 12 Alloy Overlayer by PTA Process (PTA법에 의한 스텔라이트 12 합금 육성층의 특성에 미치는 전류의 영향)

  • Jung, B.H.;Kim, M.K.;Ahan, Y.S.;Kim, M.Y.;Lee, S.Y.
    • Journal of Power System Engineering
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    • v.5 no.3
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    • pp.88-94
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    • 2001
  • Stellite 12 alloy-powders were overlaid on 410 stainless steel valve seat using plasma transferred arc(PTA) process. Variation of the microstructure, hardness, wear and corrosion of overlaid deposit with current change was investigated. The deposit showed hypoeutectic microstructure, which was consisted of primary cobalt dendrite and networked $M_7C_3$ type eutectic carbides. As current increased, the amount of eutectic carbide decreased and its dendritic secondary arm spacing increased. Hardness of the deposit was decreased with increase of current. Stress relief heat treatment at $600^{\circ}C$ for two hours resulted in slight increase of hardness in the deposit and showed uniform hardness distribution in base metal without any hardened layer in HAZ. Specific wear decreased with increase of sliding distance. The deposit of high hardness with a lot of eutectic carbide showed relatively low specific wear. Initial corrosion current density of the deposit in 0.1N sulfuric acid was lower than those of 410 stainless steel, and showed a little variation with PTA current.

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The effect of aging on the Microstructure and Hardness of Stellite 12 alloy overlayer by PTA process (PTA법에 의한 스텔라이트 12합금 육성층의 미세조직 및 경도에 미치는 시효처리의 영향)

  • 정병호;김무길;이성열
    • Journal of Advanced Marine Engineering and Technology
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    • v.26 no.1
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    • pp.68-75
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    • 2002
  • Stellite 12 alloy-powders were overlaid on 410 stainless steel valve seat by plasma transferred arc(PTA)process. Variation of microstructure and hardness of overlaid deposit with aging time at $750^{\circ}C$ was investigated. The deposit showed hypoeutectic microstructure, which was consisting of primary cobalt dendrite and networked $M_{7}C_{3}$type eutectic carbides. After aging new M_{23}C_{6}$ carbide was formed by the partial decomposition of $M_7C_3$ type eutectic carbides and finely dispersed $M_{23}C_6$ type carbides were also precipitated in the matrix. Hardness of the deposit was increased with increase of aging time at $750^{\circ}C$ and showed maximum value at 35hours. After showing maximum value, it was fallen down again at 70hours because of overaging. The increase of hardness in aging is ascribed to the formation of new stable $M_{23}C_6$ type carbide by the partial decomposition of $M_7C_3$ type eutectic carbides and also precipitation of finely dispersed $M_{23}C_6$ carbides in matrix.

Sand Casting Process Design for the Bush Parts of the Continuous Hot Zinc Plating Roll Applied to Wear-Resistant Alloy Cast Steel (내마모 합금주강 소재를 적용한 연속용융아연도금설비 Roll용 부쉬의 사형 주조공정 설계)

  • Park, Dong-Hwan;Yun, Jae-Jung;Hong, Jin-Tae;Kwon, Hyuk-Hong
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.16 no.4
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    • pp.104-112
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    • 2017
  • In the sand casting process, the flow of liquid metal affects the quality of casting products and their die life. To determine the optimal bush part design process, this study performed various analyses using commercial finite element analysis S/W. The simulation focused on the molten metal behaviors during the mold filling and solidification stages of sand casting. This study aims to develop methods to reduce the cost and increase the tool life of the continuous hot zinc plating roll.

Effect of Post-heat Treatment on Fatigue Strength of Thermally-Sprayed Stellite Alloy on Steel (스텔라이트 합금 용사 코팅의 피로 강도에 미치는 후열처리의 영향)

  • Oh Jeong Seong;Komotori Jun;Rhee Chang Kyu
    • Journal of Powder Materials
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    • v.12 no.2 s.49
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    • pp.106-111
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    • 2005
  • The effect of post-heat treatment on the coating characteristics and the fatigue strength of the gas flame thermally sprayed Stellite alloy coatings on $0.35\%$ carbon steel were investigated. The fatigue fracture surfaces of the heat treated samples were observed using SEM (Scanning Electron Microscopy). For as-sprayed samples, there was considerable scattering in the fatigue life due to the presence of the pores in the coating. After the post-heat treatment to improve the microstructural characteristics of the coating layer, the fatigue strength of the specimens was greatly improved, increasing with increasing the coating thickness. For the specimens with the 0.3mm and 0.5mm thick coating, the fatigue cracks originated in the substrate region just below the interface. On the contrary, for the specimens with the 1.0mm thick coating, they nucleated at the pore within the coating, and the fatigue strength was 2.6 times higher than that of the substrate due to the high fatigue resistance of the coating.

Preliminary Study on Pre-Heating Process of Stellite21 Powder Using Electron Beam (전자빔을 이용한 Stellite21 분말 예열공정에 관한 기초 연구)

  • Lee, Ho-Jin;Song, Jae-Guk;Kim, Jin-Suk;Ahn, Dong-Gyu
    • Journal of the Korean Society for Precision Engineering
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    • v.33 no.5
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    • pp.419-425
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    • 2016
  • A powder spreading phenomenon is one of disadvantageous characteristics of the powder bed fusion process using electron beams. The powder spreading phenomenon can be controlled using a pre-heating process of metallic powders. The aim of this paper was to investigate the preheating process of Stellite21 powder using electron beams. Powder spreading experiments were performed to examine the influence of process parameters on the spreading behaviors of Stellite21 powder. Powder heating experiments were carried to investigate the effects of the focusing current of the electron beam on the quality of the heated region. Using the results of the powder spreading and heating experiments, an appropriate combination of process parameters was obtained. The pre-heating experiment of Stellite21 was performed using the estimated combination of process parameters. The results of preheating experiments showed that the preheated Stelllite21 layer with desired characteristics can be created when the estimated combination of process parameters is applied.

A Study on the Overlay Welding Process Optimization of GTAW by Double Torch (GTAW Double Torch의 육성용접 공정최적화에 관한 연구)

  • Lim, Byung-Chul;Son, Young-San
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.17 no.3
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    • pp.73-78
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    • 2016
  • In this study, GTAW was carried out on austenitic STS316 stainless steel. Overlay welding with the stellite-base filler metal was implemented using a double torch. The response variable was calculated on the measured Vickers hardness for process optimization using the Taguchi method and its response variable was then analyzed about effect on overlay welding characteristics. The optimal process design by the Taguchi method is extremely effective in the overlay welding process for the multiple response variables. In addition, the effects of contribution rate about each response variable was analyzed easily. The conditions of the optimal process were 105A, 18V, pre-heat treatment at $200^{\circ}C$, and post weld heat treatment at $100^{\circ}C$. The Vickers hardness of the specimens produced under the optimal condition of GTAW by the double torch was 8.19% higher than that by a single torch.

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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