• Proceedings of the Korean Nuclear Society Conference
• /
• 2001.10a
• /
• pp.216-216
• /
• 2001

• Proceedings of the Korean Nuclear Society Conference
• /
• 1999.05a
• /
• pp.233-233
• /
• 1999

• Proceedings of the KWS Conference
• /
• 2001.05a
• /
• pp.297-299
• /
• 2001

• Proceedings of the KSR Conference
• /
• 2006.05b
• /
• pp.300-305
• /
• 2006

• 기계와재료
• /
• v.10 no.3 s.37
• /
• pp.130-140
• /
• 1998

• Proceedings of the KWS Conference
• /
• 1993.05a
• /
• pp.120-124
• /
• 1993

The Charpy V impact test on subsize was performed on narrow laser welds of low carbon steel sheets, joined by using a continuous wave 3kW CO$_2$ laser. Under certain conditions, a bimodal fracture behaviour has been experienced in Charpy V impact test of narrow laser beam welds. Deviation of the fracture path from the fusion zone into the base metal was dominated at high test temperature. It can be seen that the deviation always occurred after ductile initiation. If the deviation occurs on a small testing specimen, the same trend would happen on the actual laser welded structure. Fracture will then propagate through the base material even if the weld metal has low toughness.

• Proceedings of the KWS Conference
• /
• 2000.10a
• /
• pp.260-263
• /
• 2000

A methodology is developed and many used to evaluate the response sensitivity of the thermal systems to variations in their design parameters. Technique for computing the sensitivity of temperature distributions to changes in processing parameters needed for deciding the more effective laser input parameters for laser surface hardening treatment are considered. In this study, a state equation governing the heat flow in laser surface treatment is analyzed using a three-dimensional finite element method and sensitivity data of the processing parameter obtained using a direct differentiation method applied for sensitivity analysis. The interesting processing parameter is taken as the laser scan velocity and characteristic beam radius( $r_{b}$) of the sensitivity of the temperature T versus v and $r_{b}$ is analyzed. And these sensitivity results obtained in another parameters are fixed condition. To verifying the numerical analysis results, hardened layer dimensions (width and depth) of the numerical analysis compared with the results of an experimental data.ata.

• Proceedings of the KWS Conference
• /
• 2000.10a
• /
• pp.256-259
• /
• 2000

High viscosity mixing powder is a very useful material for laser cladding. This material has a high viscosity so that it can be sticked to substrate. Therefore, Laser cladding can be performed on a curved or slope surface. Laser cladding can be easily performed with the material instead of wire that is difficult to be manufactured in some case. In this experiment, it was used a high viscosity mixing powder which consists of a high temperature flux and a bronze powder. And AC2B alloy material was used as a substrate. Flux prevents the clad layer from being oxidized and increases bonding property between substrate and cladding material. It makes possible to laser cladding at low level energy.

• Journal of the Korean Society for Precision Engineering
• /
• v.14 no.6
• /
• pp.37-43
• /
• 1997

The technology of Laser lamination joining of silicon steel sheets has been studied in this paper. Conventional sheets lamination process does not meet the requirments for the improvement electric parts performance. In response to this, a new Laser spot joining method has been developed. This study performs the Laser spot lamination joining while synchronizing the sillicon steel sheets in the dies with the press movement. Several conclusions have been drawn in this paper. Effects of beam focus, power, atmosphere gas and press oil etc.

• Laser Solutions
• /
• v.3 no.2
• /
• pp.13-24
• /
• 2000

The weldability of dissimilar materials between sintered materials which are consisted of Co, Co＋Ni and carbon steel has been investigated using CO$_2$ laser. Autogeneous CO$_2$ laser welding were run along the butt between two alloys using sets of parameters variation-power and travel speed. In order to study weldability, mechanical tests (bending strength test, microhardness test) and metallurgical analyses (microstructure, phase transformation, fracture mode) were carried out. From the results obtained, it was found that the porosity which exists in a weld metal greatly affects the soundness of the weld. The optimum energy input to have a proper strength over than the requirement by a specification, found to be around 0.3-0.35kJ/m. There are two kinds of fracture mode in the weld metal, depending upon alloy combination, brittle fracture in the case of Co-carbon steel and a ductile fracture in the case of Co＋Ni-carbon steel. In general, Co＋Ni sintered material showed a better weld properties as compared to the Co sintered material.