• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.10 no.1
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• pp.45-57
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• 2000

Results of environmental monitoring for 35 steel industry welders exposed to manganese and chromium fume were evaluated. Efficiency of respiratory protectors, welding face shields and local exhaust ventilation were also evaluated to establish more efficient preventive measures that can protect welders from occupational disease as related to welding fume. The results are as follows; 1. Total fume from $CO_2$ arc welding with mild steel occurred 1.5 to 2.2 times more than that from shielded metal arc welding. Chromium and nickel fume from welding with stainless steel occurred 27 to 59 times and 18 to 30 times, respectively, than those with mild steel. 2. Proportions of water-soluble chromium(VI) and insoluble chromium(VI) Compare to total chromium occurring from $CO_2$ arc welding with stainless steel were 10.5% and 8.7%, respectively, while those with mild steel were 57.1 to 63.2% and 31.6 to 38.1%, respectively. 3. The efficiencies of 4 types of respiratory protectors to reduce welding fume exposure were evaluated as 54.4 to 64.4%. 4. The reducing effect of head type welding face shield was 67.6%, and that of hand type welding face shield was 58.5%. The highest reducing effect was shown in air supply welding face shield as 99.2%, although it is not convenient to wear. 5. When welding face shield and respiratory protectors were worn together, the reducing efficiency increased to 79.0 to 87.5%. 6. When local exhaust ventilation was installed in workplace, the reducing efficiencies varied from 31.5 to 73.1% according to the types of welding.

• Transactions of the Korean Society of Automotive Engineers
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• v.10 no.6
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• pp.158-165
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• 2002

This study was to evaluate mechanical properties and toughness of the Al5083-O aluminum alloy welding zone according to the mixing shield gas ratio and heat input change. The GMA(Gas Metal Arc) welding of the base metal was carried out with four different mixing shield gas ratios(Ar100%+He0%, Ar67%+He33%, Ar50%+He50%, and Ar33%+He67%) and three different heat inputs(low, medium, and high). To investigate the Charpy absorbed energy of the weld zone, the specimens were divided base metal, weld metal, fusion line, and HAZ notched specimen according to the worked notch position. The different gas ratio and heat input had little effect upon the tensile strength. But Ar33%+He67% mixture had the greatest mechanical properties considering that the more He gas ratio concentrations, the higher yield strength and elongation. The maximum load and displacement of the weld metal notche specimen was so much low more than that of the base metal, but fusion line and HAZ notched specimens showed almost same regardless of the mixing shield gas ratio and heat input. The Charpy absorbed energy was lowest in weld metal notched specimen, and increased in the fusion line, and HAZ notche specimen in order. Ar33%+He67% mixture had the greatest toughness considering that the more He gas ratio, the higher absorption energy.

• Journal of Welding and Joining
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• v.22 no.1
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• pp.71-76
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• 2004

In the standpoint of the arc pressure, the effects of the filler wire feed rate on the penetration was investigated in this study. The pure Ar gas was used as a shield gas and the parameters investigated were the welding current and the filler wire feed rate. By making the experiment on the arc pressure, we could know that the arc pressure was fluctuated as the depth-into-arc of the tungsten rod. Instead of the filler wire, the tungsten rod was supplied into the molten pool to make this experiment. Because the filler wire melted in arc and then we couldn't measure the arc pressure. So, the tungsten rod - the highest melting point - was used. According to the depth-into-arc of the tungsten rod, the arc pressure could be measured by using the manometer. It was proved that the arc pressure got higher as the wire feed rate was slow. It is reported the arc pressure is proportion to welding voltage and the square of welding current. But, in the filler wire TIG welding, we could blow that arc pressure was fluctuated as the depth-into-arc of filler wire was changed. We could measure the arc pressure by the variation of the filler wire feed rate and could verify that it affected bead shape and penetration.

• Proceedings of the KWS Conference
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• 1992.04a
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• pp.69-71
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• 1992

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2002.10a
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• pp.170-173
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• 2002

The object of this study is to investigate the effect of compounded welding through the AE (Acoustic Emission) characteristics on static tensile test. This study was carried out a SM 490A, high tension steel using the low hydrogen type E4316 of electronic shield metal arc welding and compound wire of $CO_2$gas arc welding. $CO_2$welding, weak in the intensity of HAZ (Heat Affected Zone), can be improved by being combined with coated arc welding, Coated arc welding, weak in the intensity of the bead, can be improved by being combined with $CO_2$welding. Especially, electronic coated arc welding and $CO_2$welding complement the mechanical intensity of HAZ and the bead with each other. So, compounded welding increases the intensity in the special parts and enhances the quality of goods.

• Journal of Welding and Joining
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• v.29 no.3
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• pp.51-57
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• 2011

Bead shape control with gas force process has been developed to overcome the concave back bead in pipe orbital welding. However, It is impossible to make a convex back bead using the existing gas nozzle, because it has high gas-consuming and low gas force. The purpose of this paper, to develop optimum shape of nozzle which to reduce the consumption of gas, maximizing the shield gas force with low cost and high productivity coincide the Green welding. In this paper venturi-type nozzle was designed by using the Venturi meter and compared velocity, pressure, arc shape in the flat position with existing CP-nozzle. As a result, Venturi-type nozzle's maximum velocity and pressure was improved at the same flow rate. Also heat input was increased by the arc contraction in the flat position.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2002.05a
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• pp.113-199
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• 2002

In this study, the toughness was evaluated by using the instrumented Charpy impact testing procedures for A15083-O aluminum alloy used in the LNG carrying and storing tank. The specimens were GMAW welded with four different mixing shield gas ratios (Ar100%+He0%, Ar67%+He33%, Ar50%+He50%, and Ar33%+He67%), and tested at four different temperatures(+25, -30, -85, and -196$^{\circ}C$ ) in order to investigate the influence of the mixing shield gas ratio and the low temperature. The specimens were divided into base metal, weld metal, fusion line, and HAZ specimen according to the worked notch position. From experiment, the maximum load increased a little up to -85$^{\circ}C$, and the maximum load and maximum displacement were shown the highest and the lowest at -196$^{\circ}C$ than the other test temperatures. The absorption energy of weld metal notched specimens was not nearly depends on test temperature and mixing shield gas ratio because the casting structure was formed in weld metal zone. In the other hand, the others specimens was shown that the lower temperature, the higher absorption energy slightly up to -85$^{\circ}C$ but the energy was decreased so mush at -196$^{\circ}C$

• Journal of Advanced Marine Engineering and Technology
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• v.26 no.6
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• pp.653-660
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• 2002

In this study, the toughness was evaluated by using the instrumented Charpy impact testing procedures for A15083-O aluminum alloy used in the LNG carrying and storing tank. The specimens were GMAW welded with four different mixing shield gas ratios (Ar100%+He0%, Ar67%+He33%, Ar50%+He50%, and Ar33%+He67%), and tested at four different temperatures(+25, -30, -85, and $-196^{\circ}C$) in order to investigate the influence of the mixing shield gas ratio and the low temperature. The specimens were divided into base metal, weld metal, fusion line, and HAZ specimen according to the worked notch position. From experiment, the maximum load increased a little up to -$85^{\circ}C$ , and the maximum load and maximum displacement were shown the highest and the lowest at -$196^{\circ}C$ than the other test temperatures. The absorption energy of weld metal notched specimens was not nearly depends on test temperature and mixing shield gas ratio because the casting structure was formed in weld metal zone. In the other hand, the other specimens were shown that the lower temperature, the higher absorption energy slightly up to $-85^{\circ}C$ but the energy was decreased so mush at $-196^{\circ}C$.

• Proceedings of the Korean Institute of Industrial Safety Conference
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• 2002.11a
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• pp.257-262
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• 2002

The object of this study is to investigate the effect of compounded welding through the AE (Acoustic Emission) characteristics for weld HAZ (Heat Affected Zone) on static tensile test. This study was carried out a SM 490A, high tension steel using the low hydrogen type E4316 of electronic shield metal arc welding, compound wire of $CO_2$ gas arc welding and tungsten electrode of TIG welding.

• Journal of Welding and Joining
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• v.27 no.1
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• pp.71-78
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• 2009

In the circumferential welding of pipe, welding phenomenon changes with the position of pipe. Especially in the overhead position, back bead of vertical-up position would be sunk. To investigate the size of back bead and keyhole with the change of the flow rate of pilot and shield gas at each position, bead-on plate welds were conducted on 6mm thickness SS400 with inclined-up position. When the rest of welding conditions remained constant, the width of back bead was increased as the flow rate of pilot gas was increased. And back bead tended to convex as the flow rate of shield gas was increased.