• 한국해양공학회지
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• 제2권1호
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• pp.135-149
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• 1988

Friction welding has been shown to have significant economic and technical advantages. However, one of the major concerns in using friction welding is the reliability of the weld quality. No reliable nondestructive test method is available at present for detecting weld quality, particularly in a production environment. Friction welds are formed by the mechanisms of diffusion as well as mechanical interlocking. The severe plastic flow at the interface by forge action of the process brings the subsurfaces so close together that detection of any unbonded area becomes very difficult. This paper presents an attempt to determine the friction weld strength quantitatively using the ultrasonic pulse-echo method. Instead of detecting flaws or cracks at the interface, the new approach calculates the coefficient of reflection based on measured amplitudes of the echoes. It has been finally confirmed that this coefficient could provide the quantitative relationship to the weld quality such as tensile strength, torsional strength, impact value, hardness, etc. So a new nondestructive analysis system of friction weld strength of dissimilar metals using an ultrasonic technique could be well developed.

• Corrosion Science and Technology
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• 제5권6호
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• pp.196-200
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• 2006

For the evaluation of corrosion resistance of Al 6061-T6 alloy, Tafel method and immersion test was performed with Friction Stir Weld(FSW) and Gas Metal Arc Weld(GMAW). The Tafel and immersion test results indicated that GMA weld was severely attacked compared with those of friction stir weld. It may be mainly due to the galvanic corrosion mechanism act on the GMA weld.

• 한국생산제조학회지
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• 제19권6호
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• pp.841-846
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• 2010

The present study examined the mechanical properties of the friction welding with hollow and solid shaft of SM45, of which the diameter is 25.2mm and 33mm. Friction welding was conducted at welding conditions of 2,000rpm, friction pressure of 50MPa, upset pressure of 70MPa, friction time of 0.4sec to 1.4sec by increasing 0.2sec, upset time of 2.0 sec including variable such as friction time are following. Under these conditions, a tensile test, a hardness test and a microstructure of weld interface were studied. The results were as follows : When the friction time was 1.0 seconds under the conditions, the maximum tensile strength of the friction weld happened to be 1,094MPa, which is 120% compared with the tensile strength of SM45C base metal. The upset length linearly increased as friction time increased. According to the hardness test, the hardness distribution of the weld interface was formed from 475Hv to 739Hv. HAZ(Heat Affected Zone) was formed from the weld interface to 2mm of SM45C.

• 한국해양공학회지
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• 제4권2호
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• pp.94-99
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• 1990

This paper deals with investigating experimentally the effects of PWHT on the weld quality such as strength, toughness, hardness and micro-structure of the welded joints in friction welding of torsion bar material SUP9A bar to bar. The results obtained are summarized as follows; 1) It was certified that the condition of the post-weld heat treatment(PWHT) for the friction welded joints was very satisfactory because both strength and toughness of the joints were improved as almost same as those of the base metal or better by the PWHT. 2) The peak of hardness distribution of the friction welded joints can be eliminated by PWHT, resulting in being almost equalized at the weld interface, the HAZ(heat affected zone) and the base metal. 3) The micro-structure of the base meta., HAZ and weld interface(WI) of friction welded joints welded at the optimum welding condition consists of the same sorbite structure obtained by PWHT and fined sorbite at WI, resulting in increasing toughness as well as strength, and no micro structural defect has been found at the friction welded zone.

• 한국해양공학회지
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• 제4권2호
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• pp.244-244
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• 1990

This paper deals with investigating experimentally the effects of PWHT on the weld quality such as strength, toughness, hardness and micro-structure of the welded joints in friction welding of torsion bar material SUP9A bar to bar. The results obtained are summarized as follows; 1) It was certified that the condition of the post-weld heat treatment(PWHT) for the friction welded joints was very satisfactory because both strength and toughness of the joints were improved as almost same as those of the base metal or better by the PWHT. 2) The peak of hardness distribution of the friction welded joints can be eliminated by PWHT, resulting in being almost equalized at the weld interface, the HAZ(heat affected zone) and the base metal. 3) The micro-structure of the base meta., HAZ and weld interface(WI) of friction welded joints welded at the optimum welding condition consists of the same sorbite structure obtained by PWHT and fined sorbite at WI, resulting in increasing toughness as well as strength, and no micro structural defect has been found at the friction welded zone.

• 한국해양공학회지
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• 제10권2호
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• pp.69-76
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• 1996

In-process quality control and high reliability of the weld are the major concerns in applying friction welding to the economical and qualified mass-production. Experimental examinations and quantitative analysis were performed for the optimiaztion of similar friction welding of hydraulic valve spool steels(SNCM220, SCM435, SACM645, SCM415, ${\varphi}24). The quantitative correlations were found between the initial cumulative counts of acoustic emission(AE) occurring during plastic deformation periods of the welding and the fatigue life as well as weld strength and welding conditions. A real-time evaluation system was developed for the friction weld quality by AE.

• 대한기계학회논문집A
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• 제33권7호
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• pp.687-692
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• 2009

The friction welding of Zr-based bulk metallic glass (BMG) rods and tubes to similar BMGs, and to crystalline metals were performed. An infrared thermal imager (FLIR-Thermal Cam SC-2000) was used to measure the temperature distribution at joining interface of the specimens during friction welding. All BMGs adopted in this study showed a successful friction joining to similar BMG. The shape of the protrusion formed at the weld interface were examined. In order to characterize the friction weld interface, the micrographic observation and the X-ray diffraction analysis on the weld cross-section were carried out. The obtained results were discussed based on the temperature distribution measured at the weld interface A successful joining of the BMGs to crystalline metals could be obtained for certain pairs of the material combination through the precise control of the friction condition. The residual strength after dissimilar friction welding of BMG was evaluated by the four-point bending test and compared with the cases of friction welding to similar materials.

• 한국공작기계학회논문집
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• 제15권1호
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• pp.63-69
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• 2006

This study deals with the friction welding of A2024- T6 to A6061- T6; The friction time was variable conditions under the conditions of spindle revolution of 2000rpm, friction pressure of 50MPa, upset pressure of 100MPa, and upset time of 5.0seconds. Under these conditions, the microstructure of weld interface, tensile fracture surface and mechanical tests were studied, of friction weld, and so the results were as follows. 1. When the friction time was 1.5seconds under the conditions, the maximum tensile strength of the friction weld happened to be 292MPa, which is $94.2\%$ of the base material's tensile strength(310MPa). At the same condition, the maximum shear strength was 2l2MPa, which is equivalent to $103\%$ of the base material's shear strength (205MPa). 2. At the same condition, the maximum vickers hardness was Hv 146 at A2024- T6 nearby weld interface, which is higher Hv3 than condition of the friction time 0.5seconds, and the maximum vickers hardness was Hvl20 from weld interface of A6061-T6, which is higher Hv28 then base material's. 3. The results of microstructure analysis show that the structures of two base materials have fractionized and rearranged along a column due to heating and axial force during friction, which has affected in raising hardness and tensile strength.

• 비파괴검사학회지
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• 제33권5호
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• pp.436-442
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• 2013

마찰용접은 축 대칭 단면금속을 용접하는 매우 유용한 결합 과정이다. 본 논문에서는 굴삭기용 호스 니플의 관대관 마찰용접을 시행하여 수송산업 등에 적용 가능성을 제안하고 마찰용접 변수의 기계적 특성을 분석하여 최적화 조건을 결정하고자 하였다. 회전속도, 마찰가열압력 및 가열시간 등 주요 변수를 선정하고 각 매개변수의 세 가지 수준에서 실험을 수행하였다. 한편, 최적의 마찰용접조건을 비파괴적으로 도출하기 위하여 음향방출기법이 적용되었으며 카운터, 이벤트 및 파형과 주파수 스팩트럼 등의 AE 파라미터들을 이용하여 마찰용접시 발생하는 신호를 분석하고자 하였다. 인장시험 결과 최적의 용접 변수는 회전속도 1300 rpm, 마찰가열압력 15 MPa, 마찰가열시간 10초로 나타났으며, 이벤트는 마찰용접된 시험편의 인장강도를 추정하는데 유용한 파라미터가 되었다.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2000년도 추계학술대회 논문집
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• pp.12-19
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• 2000

In this paper, not only the development of optimizing of friction welding with more reliability and more applicability but also development of in-process real-time weld quality(such as strength and toughness) evaluation technique by acoustic emission for friction welding of the engine exhaustive valve(SUH3-SUH35 dissimilar steels of 12.3mm, 16mm, 20mm and 24mm in diameters) were performed, comparing with the other FRW matches of materials such as SUH3 to SUH31, SUH3 to STS303 and SUH3 to STS304. As an important result, the techniques for dissimilar friction welding optimization of engine heat resisting steels SUH3 and SUH35( 12.3mm, 16mm, 20mm, 24mm) and its real-time weld quality evaluation by AE were developed, considering on both diameter and carbon equivalent effects.