• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2002년도 Proceedings of the International Welding/Joining Conference-Korea
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• pp.516-521
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• 2002

A study was carried out to grow an understanding of the microstructural development of friction stir welds on an AZ91D magnesium alloy, and to evaluate the mechanical properties of the welds. AZ91D plates with the thickness of 4mm were used, and the microstructural development of the weld zone was investigated using optical and scanning electron microscopes. Square butt welding joint with good quality was obtained at the conditions of under 187mm/min of travel speed with 1100 to 1250 rpm of tool rotation speed. The microstructure within the weld region consisted of fine equiaxed grains with no evidence of the original dendritic structure. The hardness tests showed slightly increased harness in the weld region, and the minimum hardness measured is in that of the parent material. Tensile strength of the weld zone was remarkably improved due to very fine recrystallized structure. XRD pattern of weld zone revealed the removal of $\beta$ intermetallic compounds, $Mg_{17}$Al$_{12}$, which had been distributed in the base metal.l.

• Journal of Welding and Joining
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• 제20권5호
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• pp.87-92
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• 2002

Weldability of Friction Stir Welded(FSW) AZ31B-H24 Mg alloy sheet with 4m thick was evaluated by changing welding speed. The sound welding conditions mainly depended on the suffiicient welding heat input during the process. The insufficient heat input resulted in the void like defect in the weld zone. Higher welding speed caused a larger inner void or lack of bonding. The defects were distributed at the stir zone or the transition region between stir zone and thermo-mechanical affected zone (UE). The size of defects slightly increased with increasing welding speed. These defects had a great effect on the joint strength of weld zone. The weld zone was composed of stir zone, TMAZ and heat affected zone. The stir zone was cosisted of fine recrystallized structure with $5-8\mu\textrm{m}$ in the mean grain size. The hardness of weld zone was near the 60HV, which was slightly lower than that of base metal. The maximum joint strength was about 219MPa that was 75% of that of base metal and the yield strength was also lower than that of base metal partly due to the existance of defects.

• 한국공작기계학회논문집
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• 제17권2호
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• pp.65-70
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• 2008

This study deals with the friction welding of SKH55 and SM45C; The friction time was variable conditions under the conditions of spindle revolution 2,000rpm, friction pressure of 190MPa, upset pressure of 270MPa and upset time of 2.0 seconds. Under these conditions, the microstructure of weld interface, tensile fracture surface and mechanical tests were studied, and so the results were as follows. 1. When the friction time is 1.0 seconds, the tensile strength of friction welds was 926MPa, which is around as much as 84% of the tensile strength of base metal(SKH55), the bending strength of friction welds was 1,542MPa, which is around as much as 80% of the bending strength of base metal(SKH55), the shear strength of friction welds was 519MPa, which is around as much as 70% of the shear strength of base metal(SKH55). 2 According to the hardness test, the hardness distribution of the weld interface was formed from 964Hv to 254Hv. HAZ(Heat Affected Zone) was formed from the weld interface to 1.5mm of SKH55 and 2mm of SM45C.

• Journal of Welding and Joining
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• 제15권2호
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• pp.43-53
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• 1997

The complete joining method for dissimilar press punch materials and its real-time evaluation method is not available at present. Brazing method has been used for joining them, but it is known that the welded joint by the brazing has the lower bonding efficiency and reliability than the diffusion welding. The friction welding with a diffusion mechanism in bonding was applied in this study. This work was carried out to determine the proper friction welding conditions and to analyze mechanical properties of friction welded joints of sintered carbide tool materials (SKNM50 for the blade part of press punch) to alloy steel (SCM440 for the shank part of press punch) using aluminum (A6061 for the interlayer material) as an insert material between the sintered carbide tool materials and the alloy steel. In addition, acoustic emission test was carried out during friction welding to evaluate the weld quality.

• 한국공작기계학회논문집
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• 제15권4호
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• pp.49-55
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• 2006

This study deals with the friction welding of SM25C and SCNCrM-2B; The friction time was variable conditions under the conditions of spindle revolution 2,000rpm, friction pressure of 100MPa, upset pressure of l50MPa, and upset time of 4.0 seconds. Under these conditions, the microstructure of weld interface, tensile fracture surface and mechanical tests were studied, and so the results were as follows. 1. When the friction time is 2.0 seconds, the tensile strength of friction welds was 874MPa, which is around as much as 117% of the tensile strength of base metal(SM25C), the bending strength of friction welds was 1,354MPa, which is around as much as 108.9% of the bending strength of base metal(SM25C). 2. At the same condition, the maximum vickers hardness was Hv443 at SCNCrM-2B nearby weld interface, which is higher Hv20 than condition of the friction time 0.5 seconds. 3. The results of microstructure analysis show that the structures of two base materials have fractionated and rearranged along a column due to heating and axial force during friction, which has affected in raising hardness and tensile strength.

• 한국해양공학회지
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• 제15권2호
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• pp.88-93
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• 2001

In this paper, joints of Cu-1Cr-0.1Zr alloy to STS316L were performed by friction welding method. Particularly, Cu-1Cr-0.1Zr alloy is attractive candidate as nuclear power plant material and exibit the best combination of high strength and good electrical and thermal conductivity of any copper alloy examined. The stainless steel is a structural material while copper alloy acts as a heat sink material for the surface heat flux in the first wall. So, in this paper, not only the development of optimizing of friction welding with more reliability and more applicability but also the development of in-process real-time weld quality (such as strength and toughness) evaluation technique by acoustic emission for friction welding of such nuclear reactor component of Cu-1Cr-0.1Zr alloy to STS316L steel sere performed.

• 대한기계학회논문집A
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• 제30권2호
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• pp.187-193
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• 2006

The butt and the lap welding by friction stir welding performs with $2mm^t$ 1050 aluminum alloy sheet. This paper shows behaviors of property such as vickers hardness, yielding and ultimate stresses, and macro structures for weld zone cross section of the butt and the lap jointed specimens. It is also carried out making comparison with maximum loads, stress-strain diagrams, and deformation after the guided bending test and fracture behaviors between the butt and the lap jointed specimens. It is found that the weldability of the butt jointed specimen is better than that of the lap jointed specimen.

• 한국공작기계학회논문집
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• 제17권4호
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• pp.42-50
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• 2008

Various researches to reduce weight of a vehicle are achieving. One of these researches is tendencious to manufacture the hollow piston rod using friction welding instead of solid one of the vehicle shock absorber. This study deals with the friction welding of SM45C to SM20C-pipe that is used normally in the vehicle shock absorber. The friction time was variable conditions under the conditions of spindle revolution of 2,000rpm, friction pressure of 55MPa, upset pressure of 75MPa, and upset time of 2.0seconds. Under these conditions, the microstructure of weld interface, tensile fracture surface and mechanical tests of friction weld were studied and so the results were as follows. When the friction time was l.5seconds under the conditions, the maximum tensile strength of the friction weld happened to be 837MPa, which is 113% of SM20C's tensile strength and 97% of SM45C's. The optimal welding conditions were n=2,000rpm, $P_1=55MPa$, $P_2=75MPa$, $t_1=1.5sec$, $t_2=2.0sec$ when the total upset length is 1.7mm.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2000년도 추계학술대회 논문집
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• pp.42-46
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• 2000

In this paper, joints of Cu-1Cr-0.1Zr alloy to STS316L were performed by friction welding method. Cu-1Cr-0.1Zr alloy is attractive candidate as nuclear power plant material and exibit the best combination of high sts good electrical and thermal conductivity of any copper alloy examined. The stainless steel is a structural material who alloy acts as a heat sink material for the surface heat flux in the first wall. So, in this paper, not only the develop optimizing of friction welding with more reliability and more applicabililty but also the development of in-process rear quility(such as strength and toughness) evaluation technique by acoustic emission for friction welding of such nuclear component of Cu-1Cr-0.1Zr alloy to STS316L steel were performed.

• Journal of Welding and Joining
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• 제15권6호
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• pp.78-84
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• 1997

Friction welding technique was studied to weld the turbine wheel and shaft of a turbocharger. The welding parameters were selected to investigate the effects of variables on welding quality of Inconel 713C and SCM 440. Experimental results showed that the turbine wheel and shaft could be successfully welded by friction welding. The heat affected zone was identified to be 2 mm from the weld seam. After welding, the hardness profile was found to have sudden increase and decrease for inconel 713C and SCM 440 respectively. Tensile strength of welded specimens was higher than the required strength for all of the studied welding parameters. The central portion of fracture surfaces by bending had no defects such as crack.