• Title/Summary/Keyword: Friction Welded Joints

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Influence of Welding Parameters on Macrostructure and Mechanical Properties of Friction-Stir-Spot-Welded 5454-O Aluminum Alloy Sheets (마찰교반점접합한 5454-O 알루미늄합금 판재의 접합부 거시조직 및 기계적 특성에 미치는 접합인자의 영향)

  • Choi, Won-Ho;Kwon, Yong-Jai;Yoon, Sung-Ook;Kang, Myoung-Soo;Lim, Chang-Yong;Seo, Jong-Dock;Hong, Sung-Tae;Park, Dong-Hwan;Lee, Kwang-Hak
    • Journal of Welding and Joining
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    • v.29 no.6
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    • pp.56-64
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    • 2011
  • Friction stir spot welding between 5454 aluminum alloy sheets with the different thicknesses of 1.4 and 1.0 mm was performed. In the welding process, the tool for welding was rotated ranging from 500 to 2500, and plunged to the depth of 1.8 mm under a constant tool plunge speed of 100 mm/min. And then, the rotating tool was maintained at the plunge depth during the dwell time ranging from 0 to 7 sec. The pull-out speed of the rotating tool was 100 mm/min. The increase of tool rotation speed resulted in the change of the macrostructure of friction-stir-spot-welded zone, especially the geometry of welding interface. The results of the tensile shear test showed that the total displacement and toughness of the welds were increased with the increase of the tool rotation speed, although the maximum tensile shear load was decreased. However, the change in the dwell time at the plunge depth of the tool did not produce the remarkable variation in the macrostructure and mechanical properties of the welds. In all cases, the average hardness in friction-stir-spot-welded zone was higher than that of the base metal zone. By the friction stir spot welding technique, the welds with the excellent mechanical properties than the mechanically-clinched joints could be obtained.

Creep Life Prediction of Elevated Temperature Materials for Pressure Vessel by ISM (ISM에 의한 압력용기용 고온재료의 크리프 수명예측)

  • Kong, Y.S.;Kim, H.K.;Oh, S.K.;Lim, H.K.
    • Journal of Power System Engineering
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    • v.6 no.2
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    • pp.40-47
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    • 2002
  • In this paper, friction welding optimization for 1Cr0.5Mo-STS304 (${\phi}14\;mm$), AE applications for the weld quality evaluation and the applications of various life prediction methods such as LMP (Larson-Miller Parameter) and ISM (initial strain method) were investigated : The creep behaviors of those steels and the friction welded joints under static load were examined by ISM combined with LMP at 400, 500, 550 and $600^{\circ}C$, and the relationship between these two kinds of phenomena was studied. The real-time predicting equations of elevated-temperature creep life (rupture time) under any creep stress at any elevated-temperature could be developed by LMP and LMP-ISM. It was confirmed that the life prediction equations by LMP and LMP-ISM are effective only up to 102 h and can not be used for long times of 103-106 h, but by ISM it can be used for long times creep prediction of more than 104 h with most reliability.

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Creep Life Prediction by ISM of Elevated Temperature Materials for Pressure Vessel(II) (압력용기용 고온재료의 ISM에 의한 크리프 수명예측(II))

  • 공유식;김헌경;황성필;김일석;오세규
    • Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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    • 2001.05a
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    • pp.307-313
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    • 2001
  • In this Paper, friction welding optimization for 1Cr0.5Mo-STS304($\Phi$14mm), AE applications for the weld quality evaluation and the applications of various life prediction methods such as LMP(Larson-Miller Parameter) and ISM(initial strain method) were investigated : the creep behaviors of those steels and the friction welded joints under static load were examined by ISM combined with LMP at 400, 500, 550 and $600^{\circ}C$, and the relationship between these two kinds of phenomena was studied. The real-time predicting equations of elevated-temperature creep life(fracture time) under any creep stress at any elevated- temperature could be developed by LMP and LMP-ISM, It was confirmed that the life prediction equations by LMP and LMP-ISM are effective only up to 10$^2$hrs and can not be used for long times of 10$^3$-10$^{6}$ hrs, but by ISM it can be used for long times creep prediction of more than 10$^4$hrs with most reliability.

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Optimization of FSW of Nano-silica-reinforced ABS T-Joint using a Box-Behnken Design (BBD)

  • Mahyar Motamedi Kouchaksarai ;Yasser Rostamiyan
    • Advances in nano research
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    • v.14 no.2
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    • pp.117-126
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    • 2023
  • This experimental study investigated friction stir welding (FSW) of the acrylonitrile-butadiene-styrene (ABS) T-joint in the presence of various nano-silica levels. This study aim to handle the drawbacks of the friction stir welding (FSW) of an ABS T-joint with various quantity of nanoparticles and assess the performance of nanoparticles in the welded joint. Moreover, the relationship between the nanoparticle quantity and FSW was analyzed using response surface methodology (RSM) Box-Behnken design. The input parameters were the tool rotation speed (400, 600, 800 rpm), the transverse speed (20, 30, 40 mm/min), and the nano-silica level (0.8, 1.6, 2.4 g). The tensile strength of the prepared specimens was determined by the universal testing machine. Silica nanoparticles were used to improve the mechanical properties (the tensile strength) of ABS and investigate the effect of various FSW parameters on the ABS T-joint. The results of Box-Behnken RSM revealed that sound joints with desired characteristics and efficiency are fabricated at tool rotation speed 755 rpm, transverse speed 20 mm/min, and nano-silica level 2.4 g. The scanning electron microscope (SEM) images revealed the crucial role of silica nanoparticles in reinforcing the ABS T-joint. The SEM images also indicated a decrease in the nanoparticle size by the tool rotation, leading to the filling and improvement of seams formed during FSW of the ABS T-joint.

Failure Mode Analysis and Friction Material Development of the KTX tread Brake (고속철도 제륜자 결함분석 및 제륜자 개발)

  • Baek, Jong-Kil;Goo, Byeong-Choon;Koo, Jeong-Seo
    • Journal of the Korean Society for Railway
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    • v.14 no.2
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    • pp.109-115
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    • 2011
  • The shoe brake of the KTX is used in low speed when the electric brake is not effective. The main purpose of the shoe brake is to stop the train to a desired stop point at the station. Lots of defects have been encountered in the shoe brake unit since the KTX started its operation. To improve the reliability of shoe brake unit of the KTX power car, first of all, failure modes of the KTX shoe brake unit were analyzed. Main failure modes are cracks in the shoe friction material and fracture in the welded joints of the shoe backing steel structure. Several methods to remove the defects of the shoe brake unit were proposed and on-board tests were carried out: Increase of the strength of the shoe key and shoe cam, which decreased a little the occurrence of cracks in the shoe friction material; Redesign of the shoe backing steel structure, which eliminated the occurrence of the cracks in the backing plate but could not solve completely the crack problem in the shoe friction material; Development of a new friction material, which with redesign of the shoe backing steel structure could solve satisfactorily the crack problem in the shoe friction material.

Evaluation of Mechanical Properties of Extruded Magnesium Alloy Joints by Friction Stir Welding : Effect of Welding Tool Geometry (마찰교반용접 툴 변화에 따른 마그네슘 합금 압출 판재 마찰교반용접부 기계적 물성 평가)

  • Sun, Seung-Ju;Kim, Jung-Seok;Lee, Woo-Geun;Lim, Jae-Yong
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.17 no.10
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    • pp.280-288
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    • 2016
  • This study proposes improved welding tools for magnesium alloys. Two types of tools were used for friction stir welding (FSW). The effect of the welding tools on the FSW joints was investigated with a fixed welding speed of 200mm/min and various rotation speeds of 400 to 800 rpm. After FSW, the joints were cross-sectioned perpendicular to the welding direction to investigate the defects. A tensile test and Vickers hardness test were conducted to identity the mechanical properties of the joints. Defects were observed when the rotation speed was 400 rpm, regardless of the welding tool, and the amount of defects tended to decrease with increases in rotational speed. Defect-free welds were obtained when the rotation speed was 800 rpm. The best weld quality was acquired using the C type welding tool. The rotation speed of 800 rpm and welding speed of 200 mm/min produced the best joining properties. The ultimate tensile strength, yield strength, and elongation of the welded region were 90.0%, 69.1%, and 83.2% those of the base metal, respectively.

Effect of Crack Orientation on Spatial Randomness of Fatigue Crack Growth Rate in FSWed 7075-T651 Aluminum Alloy Joints (마찰교반용접된 7075-T651 알루미늄 합금 용접부의 피로균열전파율의 공간적 변동성에 미치는 균열 방향의 영향)

  • Jeong, Yeui-Han;Kim, Seon-Jin
    • Journal of Power System Engineering
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    • v.18 no.1
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    • pp.91-98
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    • 2014
  • In this investigation, the effect of crack orientation on spatial randomness of fatigue crack growth rate (FCGR) in friction stir welded (FSWed) 7075-T651 aluminum alloy joints has been statistically analyzed by Weibull distribution. The fatigue crack growth tests are conducted under three different constant stress intensity factor range (SIFR) control at room temperature with R = 0.1 and frequency 10Hz on compact tension (CT) specimen machined at base metal (BM) and weld metal (WM). The experimental fatigue crack growth rate data were obtained for two types of specimens having LT and TL orientations. LT specimens both base metal and weld metal showed higher fatigue crack growth rate as compared to TL specimens. In the lower SIFR region, FCGR were found to be almost 3 times higher in higher SIFR region. The shape parameter of Weibull both LT and TL orientation for FCGR was increased with increasing SIFR, the scale parameter was also increased with increasing SIFR. The smallest value of the shape parameter was shown in weld metal specimens having LT orientation at lower SIFR region.

A Study on the Relationship between Dissimilar Metals Friction Welded Joints Strength Properties and Ultrasonic Reflection Coefficients (이종재 마찰용접부 강도특성과 초음파 반사계수와의 상관성에 관한 연구)

  • S. K. Oh;D. J. Kim;S. D. Han
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.23 no.2
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    • pp.34-34
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    • 1987
  • Friction welding has emerged as a reliable process for high-production commercial application with significant economic and technical advantages. But nondestructive test in friction weld was not clearly developed. Therefore the experimental verification is necessary in order to understand the characteristics of the pulse echo effects according to various change in welding conditions. This paper presents a new attempt to detect the bond strength of friction welds by ultrasonic. Instead of looking for a flaw or cracks at the interface, the new approach evaluates the coefficient by reflection which provides a single quantitative indicator involving the acoustic energy reflected at the interface. The objective of this study is to find the relationship between the reflection coefficients and the weld strength. Results of the bar-to-bar friction welding of aluminum to copper and stainless steel and such relationship investigation are presented and interpreted.

A Study on the Relationship between Dissimilar Metals Friction Welded Joints Strength Properties and Ultrasonic Reflection Coefficients (이종재 마찰용접부 강도특성과 초음파 반사계수와의 상관성에 관한 연구)

  • O, Se-Gyu;Kim, Dong-Jo;Han, Sang-Deok
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.23 no.2
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    • pp.80-85
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    • 1987
  • Friction welding has emerged as a reliable process for high-production commercial application with significant economic and technical advantages. But nondestructive test in friction weld was not clearly developed. Therefore the experimental verification is necessary in order to understand the characteristics of the pulse echo effects according to various change in welding conditions. This paper presents a new attempt to detect the bond strength of friction welds by ultrasonic. Instead of looking for a flaw or cracks at the interface, the new approach evaluates the coefficient by reflection which provides a single quantitative indicator involving the acoustic energy reflected at the interface. The objective of this study is to find the relationship between the reflection coefficients and the weld strength. Results of the bar-to-bar friction welding of aluminum to copper and stainless steel and such relationship investigation are presented and interpreted.

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Effects of Postweld Aging Treatment on Rotary Bending Fatigue strength of Friction Welded Joints at Elevated Temperature (마찰 용접부의 고온 회전굽힘 피로 강도에 미치는 용접후 시효열처리의 영향에 관한 연구)

  • Oh, Sae Kyoo
    • Journal of Advanced Marine Engineering and Technology
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    • v.7 no.2
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    • pp.36-49
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    • 1983
  • 최근 높은 경제성과 용접성의 우수성에 의한 마찰 용접의 응용에 있어서 내열.내식 재료가 개스터어빈, 기관, 핵 발전기등의 기계 부품 생산 공업에 널리 이용되고 있다. 따라서 이종내열 합금강의 마찰 용접된 부품을 이용함에 있어서 내식.내마모 및 용접성 뿐만 아니라 고온 피로 강도와 크리이프 강도 등의 복합 특성에 관한 연구가 요구되고 있다. 본 연구에서는 마르텐사이트계 실크롬 내열강과 오오스테나이트계 닉켈크롬 스테인레스강의 이종 내식.내열 합금강의 최적 용접조건하에서 마찰 용접된 후의 시효 열처리가 용접재의 700 .deg.C 고온 회전 굽힘 피로강도 특성에 미치는 영향에 관하여 실험과 강도해석에 의해 조사되었고 용접후의 용체화 처리와 시효 열처리법에 의한 내열강 마찰 용접강도 개선법을 개발코저한 것이다.

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