• Title, Summary, Keyword: Upsetting time

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Optimization for Friction Welding of AZ31 Mg Alloy by Design of Experiments (실험계획법에 의한 AZ31마그네슘합금의 마찰접합시 최적공정설계)

  • Kang, Dae-Min;Kwak, Jae-Seob;Choi, Jong-Whan;Park, Kyeong-Do
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.10 no.4
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    • pp.64-69
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    • 2011
  • Magnesium alloy has been known as lightweight material in automobile and electronic industry with aluminum alloy, titanium alloy and plastic material. Friction welding is useful to join different kinds of metals and nonferrous metals they are difficult to be joined by such as gas welding, resistance welding and electronic beam welding. In this study, friction welding was performed to investigate optimization process of Mg alloy with a 20mm diameter solid bar. For that, the orthogonal array $(L_{9}(3^{4}))$ was used that contained four factors and each factor had three levels. Control factors were heating pressure, heating time, upsetting pressure and upsetting time. Also tensile tests were carried out to measure mechanical properties for welded conditions. The levels of heating pressure and upsetting pressure used were 15, 25, 35MPa, and 30, 50, 70MPa, respectively. In addition those of heating time and upsetting time were 0.5, 1, 1.5 sec and 3, 4, 5 sec., respectively, rotating speed of 2000rpm. From the experimental results, optimization condition was estimated as follows; heating pressure=35MPa, upsetting pressure=70MPa, heating time=1.5sec, upsetting time=3sec.

Mechanical Properties of Friction Joint of AZ31Mg Alloy (AZ31마그네슘합금의 마찰접합특성)

  • Kong, Y.S.;Chun, B.K.;Kang, D.M.
    • Transactions of Materials Processing
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    • v.19 no.5
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    • pp.277-282
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    • 2010
  • Magnesium alloy has been known as lightweight material in automobile and electronic industry with aluminum alloy, titanium alloy and plastic material. Friction welding is useful to join various metals and nonferrous metals that are difficult to join by such as gas welding, resistance welding and electronic beam welding. In this study, friction joining was performed to investigate mechanical properties of Mg alloy with 20mm diameter solid bar. Also the optimal joining conditions for its application were determined on the basis of tensile test, and hardness survey. The joining parameters were chosen as heating pressure, heating time, upsetting pressure, and upsetting time. Heating and upsetting pressure were executed under the range of 10~40MPa and 20~80MPa, respectively. From the experimental results, optimal joining conditions were determined as follows; rotating speed=2000rpm, heating pressure=35MPa, upsetting pressure=70MPa, heating time=1sec, upsetting time=5sec. Also the hardness of jointed boundary showed as HV50 which was similar to that of base metal at the optimal condition, and it was supposed that zone of HAZ was 8mm. Finally two materials were strongly mixed at interface part to show a well-combined microstructure without particle growth or any defect.

Process Design for Manufacturing 1.5wt%C Ultrahigh Carbon Workroll: Void Closure Behavior and Bonding Strength (1.5wt%C 초고탄소 워크롤 제조를 위한 단조 공정 설계: 기공압착 및 접합강도 분석)

  • Lim, H.C.;Lee, H.;Kim, B.M.;Kang, S.H.
    • Transactions of Materials Processing
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    • v.22 no.5
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    • pp.269-274
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    • 2013
  • Experiments and numerical simulations of the incremental upsetting test were carried out to investigate void closure behavior and mechanical characteristic of a 1.5wt%C ultra-high carbon steel. The experimental results showed that the voids become quickly smaller as the reduction ratio increases. The simulation results confirmed this behavior and indicated that the voids were completely closed at a reduction ratio of about 40~45% during incremental upsetting. After the completion of the incremental upsetting tests, the process of diffusion bonding was employed to heal the closed voids in the deformed specimens. To check the appropriate temperature for diffusion bonding, deformed specimens were kept at 800, 900, 1000 and $1100^{\circ}C$ for an hour. In order to investigate the effect of holding time for diffusion bonding at $1100^{\circ}C$, specimens were kept at 10, 20, 30, 40, 50 and 60minutes in the furnace. A distinction between closed and healed voids was clearly established using microstructural observations. In addition, subsequent tensile tests demonstrated that complete healing of a closed void was achieved for diffusion bonding temperatures in the range $900{\sim}1100^{\circ}C$ with a holding time larger than 1 hour.

Finite Element Simulation of a Pore Closing Process during Upsetting in Open Die Forging (자유단조에서 업세팅 공정 중 기공 압착 과정의 유한요소 시뮬레이션)

  • Lee, M.C.;Cho, J.H.;Choi, I.S.;Jang, S.M.;Joun, M.S.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • pp.79-83
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    • 2008
  • We carry out three-dimensional simulation of pore closing processes during upsetting in open die forging. Several pores on a plane section of a cylindrical material are traced at the same time and the results of hydrostatic pressure and effective strain are discussed to reveal the parameters affecting pore closing phenomena. Five different sizes of pores are also investigated by simulation to reveal the pore size effect in pore closing during upsetting. AFDEX 3D is employed for this study.

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Evaluation on Dynamic Behavior of Friction Welded Joints in Alloy718 to SCM440 using Acoustic Emission Technique (Alloy718/SCM440 마찰용접재의 AE에 의한 동적 거동평가)

  • Kim, Dong-Gyu;Kong, Yu-Sik;Lee, Jin-Kyung
    • Journal of the Korean Society of Industry Convergence
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    • v.22 no.5
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    • pp.491-497
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    • 2019
  • Dissimilar friction welding were produced using 15 mm diameter solid bar in superalloy(Alloy718) to chrome molybdenum steel(SCM440) to investigate their mechanical properties. Consequently, optimal welding conditions were n=2000 rpm, HP=60 MPa, UP=120 MPa, HT=10 sec and UT=10 sec when the metal loss(Mo) is 3.5 mm. Acoustic Emission(AE) technique was applied to analyze the dissimilar friction welding of Alloy718 and SCM440. The relationship between the AE parameters and dissimilar friction welding of both material was discussed. In the case of heating time of 6 sec, 10 sec, 14 sec and 20 sec, 5 AE events per 0.5 seconds and energy about $2.7{\times}10^{10}$ were exhibited in heating time. In upsetting time, resulting in various numbers of events per second and very low energy. The frequency range of the signal generated during the heating time was about 200 kHz. However, the upsetting time resulted in a wide range of signals from very low frequency to high frequency of 500 kHz due to rapid plasticity of the material.

A Study on Friction Welding of Localized SPS5 Spring Steel (국산 SPS5 스프링강의 마찰용접에 관한 연구)

  • Jeong, S.U.
    • Proceedings of the KSME Conference
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    • pp.803-808
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    • 2000
  • This thesis studied whether friction welding of SPSS, localized torsion bar material could be accomplished or not. And then optimum welding conditions were examined and leaded through tensile, impact, torsion and hardness test after postweld heat treatment of the actual field condition. Obtained results were as follows; Linear relationship was existed between heating time and total upset, and a quadratic equation model could be made between tensile strength and heating time. Optimum welding conditions with fine structure were as follows in case total upset(U)=8.5mm; the number of rotations(n)=2,000 rpm, heating pressure($p_1$)=80MPa, upset pressure($p_2$)=200MPa, heating time($t_1$)=4sec, upset time($t_2$)=3 sec.

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A Study on Fatigue Characteristics of Dissimilar Spring Steel(SUP9A)-SM25C by Friction Welding (스프링강(SUP9A)-SM25C의 이종재 마찰용접 피로특성에 관한 연구)

  • 정석주;이기중
    • Journal of the Korean Society of Safety
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    • v.16 no.3
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    • pp.19-25
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    • 2001
  • The friction-welding SM25C is a substitute for the suing steel that is utilized in the machinery, airplane, and automobile, ok. This substitution would provide reduction of material and weight of welding parts. From the result we found that the strength of the friction welded joint was 529-617MPa and the toughness 1.2 times higher than that of the base metal. The optimal condition of friction welding was found as follows : n=2000rpm, $P_1$=68㎫, $P_2$=137MPa, $t_2$=2sec, $t_1$=2-4sec, Considering the strength, the hardness, and the reduction of area in the friction welding, the fiction welding using SUP9A and SM25C was found to cause no problem in on-the-job application.

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A study on welding structure and thermal behavior in friction welding of austenitic stainless steel (오스테나이트계 스테인레스강의 마찰압접시 압접조직과 열적거동에 관한 연구)

  • 강춘식;정태용
    • Journal of Welding and Joining
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    • v.8 no.1
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    • pp.43-53
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    • 1990
  • The transient temperature distribution in the continuous friction welding 304 stainless steel bars is investigated by experimental and analytical methods. It is calculated by F.D.M. (finite difference method). The heating pressure, the rotational speed and friction coefficient obtained from experiment are used to determine the heat input at the contacting surface. Thermal properties of the workpiece are the function of temperature. The calculated temperature is well coincided with the measured value. The grain size at weld interface is extremely small due to the severe plastic deformation at high temperature, and result of this refined zone reveals higher hardness value. Because the HAZ is very narror about 2-3 mm, welding defects do not occure.

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Study on Real-Time Weld Quality Evaluation by Acoustic Emission for Production of Drills by Friction Weldiing (마찰용접에 의한 드릴 생산에서의 AE에 의한 실시간 품질평가에 관한 연구)

  • 오세규;윤인진;오정환;오명석
    • Journal of Ocean Engineering and Technology
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    • v.7 no.2
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    • pp.121-130
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    • 1993
  • A study off riction welding of high speed steel(SKH 51) bar for blade side to carbon steel(STC 3)bar for shank side was carried out experimentally through tensile test, hardness test, microstructure, and acoustic emission (AE) test. So, this paper deals with optimizing the welding conditions and the real-time quality (strength) evaluation of friction weleded joints by acoustic emission technique. The results obtained are summarized as follows: (1) For friction welded joints of SKH 51to STC 3 steel bars, the total upset (U) increases linearly with an increase of heating time (t sub(1)). (2) The determined optimum welding conditions are heating time (t sub(1)) 7-9 sec, upsetting time (t sub(2)) 5 sec, heating pressure(P sub(1)) 12 kg sub(f)mm supper(2), upsetting pressure (P sub(2)) 15 kg sub(f) mm supper(2) and rotating speed (n) 2, 000 rpm, resulting in a computed relationship between the tensile strength of the joint .sigma. (kg sub(f) mm supper(2)) and the heating time t sub(1) (sec) as the following. sigma.=2.39t sub(1)

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FE Analysis for the Prediction of Void Closure on the Free Forging Process of a Large Rotor (대형 로터의 자유단조공정에서 기공압착 예측을 위한 유한요소해석)

  • Lee, K.J.;Bae, W.B.;Kim, D.K.;Kim, Y.D.;Cho, J.R.
    • Transactions of Materials Processing
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    • v.16 no.2
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    • pp.126-131
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    • 2007
  • Voids in a large rotor are formed in solidification process of a cast ingot. The voids have to be eliminated from the rotor by a forming process, because they would became stress-intensity factors which suddenly fracture the rotor in the operation. Previous studies on void-elimination of a large rotor have mainly focused on finding the process variables affecting the void-closure. But the study on the amount of void closure in a large rotor has been very rare. This study was performed to obtain an equation which predicts the amount of void-closure in a forging process of a large rotor and to evaluate the availability of the void-closure equation through finite element analyses. Firstly, 2D FE analysis was carried out to find effects of time integral of hydrostatic stress and effective strain on void volume rate of a large rotor in the upsetting process for various diameters and shapes of void, and material temperature. From the 2D FE analysis, we found that effective strain was suitable for predicting the void-closure of a large rotor, because there was a constant relationship between void volume rate and effective strain. And a void-closure equation was proposed fur predicting void-closure of a large rotor in the upsetting process. Finally, ken the 3D FE analysis, the proposed void-closure equation was verified to be useful for upsetting and cogging processes.