• 소성∙가공
• /
• 제27권1호
• /
• pp.37-47
• /
• 2018

In this paper, a double spot welding process, utilizing electric resistance heating dies, is suggested for the spot welding of dissimilar metal plates for drawing and concurrent spot welding. This double welding process has two heating methods for the fusion welding at the interfacial zone between steel and aluminum plates, such as heating method by thermal conduction of electric resistance by welding current induced to heating dies, and heating method by electric resistance between contacted surfaces of two plates by welding current induced to copper electrode. This double welding process has welding variables such as each current induced in heating dies and in copper electrode, outer diameters of heating dies, and edge shape of copper electrode. Experiments for current conditions in welding process should be demanded in order to get successful welding strength. It was known that the welding strength could be reached to the value demanded on industry fields under such welding conditions as heating dies of outer ring dia.12mm contacted on steel plate, as heating dies of outer ring dia. 14mm contacted on aluminum plate, and as copper electrode of dia. 6.0mm, and as 3 times continuous heating method by $1^{st}$ current of 11 kA(9cycle), $2^{nd}$ current 11 kA(60cycle), $3^{rd}$ current 7 kA(60cycle) applied in steel heating dies and copper electrodes, flat edge of copper electrode, for double spot welding process of dissimilar metal plates of steel and aluminum of 1.0 mm thickness.

• 대한용접접합학회:학술대회논문집
• /
• 대한용접접합학회 2008년도 춘계학술발표대회 개요집
• /
• pp.51-51
• /
• 2008

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2008년도 춘계학술대회 논문집
• /
• pp.523-524
• /
• 2008

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 1996년도 춘계학술대회 논문집
• /
• pp.778-782
• /
• 1996

By the use of a similar numerical method as that in the previous paper, the forming limit strain of bonded sheet metals is investigated, in which the FEM is applied and J2G(J2-Gotoh's corner theory) is utilized as the plasticity constitutive equation. Bonded two-layer sheets and sheets bonded with dissimilar sheets on both surface planes are stretched in a plane-strain state, with various work-hardening exponent n-values and thicknesses of each layer. Processes of shear-band formation in such composite sheets are clearly illustrated. It is concluded that, in the bonded state, the higher limiting strain of one layer is reduced due to the lower limiting strain of the other layer and vice versa, and does not necessarily obey the rule of linear combination of the limiting strain of each layer weighted according thickness.

• International Journal of Korean Welding Society
• /
• 제3권2호
• /
• pp.46-52
• /
• 2003

The refinement of microstructure and phase transformation near the interface of pure copper/carbon steel dissimilar metals joints with various friction welding parameters have been studied in this paper. The microstructure of copper and carbon steel joints were changed to be a finer grain compared to those of the base metals due to the frictional heat and plastic deformation. The microstructure of copper side experienced wide range of deformed region from the weld interface and divided into very fine equaxied grains and elongated grains. Especially, the microstructures near the interface on carbon steel were transformed from ferrite and pearlite dual structure to fine ferrite, grain boundary pearlite and martensite due to the welding thermal cycle and rapid cooling rate after welding. These microstructures were varied with each friction welding parameters. The recrystallization on copper side is reason for softening in copper side and martensite transformation could explain the remarkable hardening region in carbon steel side.

• 한국결정성장학회지
• /
• 제26권1호
• /
• pp.19-22
• /
• 2016

1990년대 후반 3D Printer를 활용한 CAD/CAM 시스템의 도입은 주얼리 산업에 많은 변화를 가져오게 되었다. 2009년 FDM방식의 특허 만료를 시작으로 주요 특허가 풀리면서 저가의 3D Printer가 주얼리 산업에 보급되었다. 주얼리 대량생산프로세스는 3D Printer가 생산라인의 한 부분을 차지하는 직접제조 프로세스로 변화할 것이다. 이러한 변화에 본 연구는 3D Printer를 활용한 주얼리 제조 프로세스를 제시하고, 다른 색상의 이종금속이 접합된 주얼리 시제품을 제작하였다. 이를 통하여 3D printer의 활용범위를 높이고, 주얼리 대량생산 방법의 다양성을 제시하였다.

• Journal of Welding and Joining
• /
• 제23권6호
• /
• pp.43-48
• /
• 2005

This work was carried out to obtain sound welds and to select a most suitable binary metal joint among three different dissimilar binary metal combinations such as Zr-4/Ta, Mo/Ta and Ti/Ta(seal tube/sensor sheath) joints fur the instrumented nuclear fuel irradiation test. To do this, Taguchi experimental method was employed to optimize the experimental data. In addition, metallography, micro-focus x-ray radiography and hardness test were conducted to examine the welds. From the weld bead appearance, penetration depth and bead width as well as weld defects standpoint, Zr-4/Ta joint is suggested for the circumferential joining between a seal tube and a sensor sheath. The optimized welding parameters based on Zr-4/Ta joint are suggested as well.

• Nuclear Engineering and Technology
• /
• 제54권8호
• /
• pp.2755-2770
• /
• 2022

The need for Dissimilar Welded Joint (DWJ) in the power plant components arises in order to increase the overall efficiency of the plant and to avoid premature failure in the component welds. The Activated-Tungsten Inert Gas (A-TIG) welding process, which is a variant of Tungsten Inert Gas (TIG) welding, is focus of this review work concerning the DWJ of nuclear grade creep-strength enhanced ferritic/martensitic (CSEF/M) steels and austenitic steels. A-TIG DWJs are compared with Multipass-Tungsten Inert Gas (M-TIG) DWJ based on their mechanical and microstructural properties. The limitations of multipass welding have put A-TIG welding in focus as A-TIG provides a weld with increased depth of penetration (DOP) and enhanced mechanical properties. Hence, this review article covers the A-TIG welding principle and working parameters along with detailed analysis of role played by the flux in welding procedure. Further, weld characteristics of martensitic and austenitic steel DWJ developed with the A-TIG welding process and the M-TIG welding process are compared in this study as there are differences in mechanical, microstructural, creep-related, and residual stress obtained in both TIG variants. The mechanics involved in the welding process is deliberated which is revealed by microstructural changes and behavior of base metals and WFZ.

• Journal of Welding and Joining
• /
• 제30권6호
• /
• pp.15-20
• /
• 2012

Brazing technology has been widely used among bonding technologies because it enables to bond various metals, even ceramics, dissimilar metals, and give higher bonding strength, cost down, automation, etc. However, there are many parameters to achieve optimal brazing joint such as brazing alloys, brazing atmospheres, designs and brazing methods, etc. The brazing parameters affect seriously on the characteristic of final brazing products. Stainless steel is broadly used in high temperature applications, chemical industry, heat exchangers, muffler of vehicles, and so on. Accordingly, in this article, brazing alloys, forms of brazing alloys, brazing methods and atmospheres for stainless steel were described.

• Journal of Welding and Joining
• /
• 제34권5호
• /
• pp.33-40
• /
• 2016

The microstructures and the creep rupture properties of dissimilar welds between the Ni-based superalloy Inconel 740H and the non-stabilized austenitic stainless steel TP316H have been characterized. The welds were produced by shielded metal arc (SMA) welding process with the AWS A5.11 Class ENiCrFe-3 filler metal, commonly known as Inconel 182 superalloy. Postweld heat treatment at $760^{\circ}C$ for 4 hours was conducted to form ${\gamma}^{\prime}$ strengthener in Inconel 740H. The austenitic weld metal produced by Inconel 182 had a dendritic microstructure, and grew epitaxially from the both sides of Inconel 740H and TP316H base metals. Since both Inconel 740H and TP316H did not undergo any solid-state transformation during welding process, there were no heat-affected-zone (HAZ) sub-regions and the coarsoned grains near the weld interface were limited to a narrow region. The hardness of Inconel 182 weld metal was ~220 Hv. The gradual hardness decrease was detected at HAZ of TP316H, and the TP316H base metal displayed the lowest hardness value (~180 Hv) whilst the Inconel 740H showed the highest hardness value (~400 Hv). Fracture after creep occurred at the center of weld metal, regardless of creep condition. It was found that during creep the cracks initiated and propagated along interdendritic regions and grain boundaries at which Laves particles enriched in Nb, Si and Cr were present. The appropriate design of weld metal was discussed to suppress the creep-induced cracking of the present dissimilar weld.