• Title/Summary/Keyword: 너깃직경

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A Study on Prediction of Nugget Diameter by Resistance Spot Welding Finite Element Analysis of High Tensile Steel (SGAFC 780) (고장력 강판(SGAFC780)의 저항 점 용접의 유한요소해석을 통한 너깃 직경 예측)

  • Lee, Cheal-Ho;Kim, Won Seop;Lee, Jong-Hun;Park, Sang-Heup
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.20 no.11
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    • pp.144-150
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    • 2019
  • In this study, resistance spot welding was performed using a high tensile steel plate SGAFC 780. The shear tensile strength, fracture profile, nugget diameter, and simulation were compared according to the conditions. After the nugget diameter calibration, the minimum diameter of welding was more than 4.3mm when the welding current was 8kVA or more. At 9kVA and above 10kVA, the minimum nugget diameter of 4.3mm was satisfied. On the other hand, due to the high current and time, the fly phenomenon occurred and the deep indentation remained. An evaluation of the weldability confirmed that there was an interval that was evaluated as weld failure due to the creep phenomenon, which satisfied the tensile shear strength and minimum nugget diameter. On the other hand, areas that have sufficient load bearing capacity even when drift has occurred were also identified. The simulation results show that the error rate was less than 4.2% when comparing the nugget diameter in the simulation and the experimental results in the appropriate weld zone, and confirmed the reliability of the simulation.

Evaluation of Welding Characteristics on 3-lap Spot Joint of Zinc Coned Seel Sheet md High Seength Steel Sheet (아연도금 강판과 고장력 강판 3겹 점용접물의 용접특성 평가)

  • Kwon Il-Hyun;Kim Hoi-Hyun;Baek Seung-Se;Yang Seong-Mo;Yu Hyo-Sun
    • Transactions of the Korean Society of Automotive Engineers
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    • v.13 no.5
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    • pp.42-49
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    • 2005
  • In general, multi-lap spot weld joints are frequently present in automobile. Most research, however, has been focused on the single-lap spot weld joints until now. In this paper, tensile-shear strength tests are performed to examine the weldability of 3-lap spot joint welded by using the high strength steel sheet and the zinc coated steel sheet. The indentation depth and nugget diameter are used to propose the optimum welding conditions. The weldability is affected by the welding current and welding time for 3-lap spot joint. Meanwhile the expulsions is round to decrease with the increase of electrode force. The optimum welding conditions are presented for 3-lap spot joints of high strength steel sheet and zinc coated steel sheet.

Effect of Si content on Nugget Diameter of Electric Resistance Spot Welded Dual Phase Steel (DP강의 전기저항점용접부 너깃직경에 미치는 Si 함량의 영향)

  • Kong, Jong-Pan;Kang, Gil-Mo;Han, Tae-Kyo;Chin, Kwang-Geun;Kang, Chung-Yun
    • Journal of Welding and Joining
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    • v.29 no.5
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    • pp.99-105
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    • 2011
  • In this study, effect of Si content on nugget diameter in electric resistance spot welded dual-phase(DP) steel was investigated. The cold rolled DP steels with different Si content (0.5, 1.0, 1.5, 2.0 wt.%) were used and thickness of those sheet was 1.2mm. With increasing Si content, nugget diameter was increased at the same welding current. This is attributed to increase of heat input result from high resistivity. Also, nugget diameter was increased with an increase in Si content for the same heat input. For this reason, the melting point of DP steel is lowered with an increase in the Si content. And solid DP steel can easily be transformed to a liquid phase because the low melting point. Finally, a prediction formula for the nugget diameter(N.D.) could be obtained in terms of heat input(Q) and melting point(M.P) as follows: N.D.(mm) = 0.11Q(J) - 0.0031 M.P.($^{\circ}C$) + 0.32.

Evaluation of Resistance Spot Weldability of SGAFC1180 Steel (SGAFC1180 TRIP강재의 저항 점용접성 평가)

  • Shin, Seok-Woo;Lee, Jong-Hun;Kim, Dae-Hwan;Park, Sang-Heup
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.18 no.12
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    • pp.644-649
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    • 2017
  • In the automobile industry, there is growing demand for lightweight vehicles due to environmental problems and rising oil prices. Therefore, aluminum alloys and special materials are being used to reduce the weight of vehicles, but there are still many difficulties to overcome in terms of cost and strength. Therefore, the application of advanced high strength steel (AHSS)is increasing. AHSS has good strength and formability.Safety regulations are becoming stricter, and 1.2-GPa super-high-strength steels are gradually being applied for the center pillar and roof rails. Thus, the application of different kinds of steels in automobile bodiesis also increasing gradually. This study evaluates the resistance point weldability and the characteristics of a welded part of SGAFC1180 1.2t steel. A simulation was used to observe the nugget formation and its growth behavior. The prediction performance showed a similar tendency within an error rate of 10%. Also, the effect of this behavior on the process resistance and dynamic resistance was investigated,along with the correlation between the shear tensile strength and nugget diameter.