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Abstract
Purpose
The purpose of this study was to compare Ni-Cr alloy property of gas-oxygen torch soldering and infrared welding using optical microscope and Electron Probe Micro
Analyzer (EPMA).
Materials and methods
Ni-Cr alloys were casted for specimens. Specimens had 3.0 mm diameter, 30.0 mm length and were divided into two groups. Each group had 4 specimens. One group was for gas-oxygen torch soldering and the other was infrared welding. Specimens were cut with low-speed disc and soldered each other with gas-oxygen torch and infrared machine. After soldering and polishing, specimens were observed at 3 points (soldering point, 5 mm distance point, 10 mm distance point) with optical microscope and analyzed 3 points (soldering point, 5 mm distance point, 10 mm distance point with EPMA.
Results
The results of this study were as follows: 1. The observation of gas-oxygen torch soldering at 10 mm distance point under the optical microscope was not founded any specific surface properties, but some crack lines were observed at 5 mm distance and soldering point. 2. There were no crack lines were founded at the observation of infrared welding at 10 mm distance and 5 mm distance points under the optical microscope. However, at the 5 mm distance, the surface was not smooth enough compared with at 10 mm distance point. Some crack lines were observed at the welding point as well. 3. In the EPMA analysis of the gas-oxygen torch soldering, the component of Ni was increased by 4.5%, Cr was increased by 7.5% than that of the Ni-Cr alloy at the 10.0 mm distance. At the 5 mm distance, the component of Ni was decreased by 6.1%, Mo was increased by 9.0% than that of the Ni-Cr alloy but Cr was equally shown at the 5.0 mm distance. Only Ni was shown at the soldering point. 4. In the EPMA analysis of the infrared welding, the component of Ni was increased by 9.1%, Cr was increased by 0.4% than that of the Ni-Cr alloy but Al was equal at the 10.0 mm distance. At the 5 mm distance, the component of Ni was increased by 4.7%, Cr was increased by 4.7% and Al was increased by 0.1% than that of the Ni-Cr alloy. At the welding point, the component of Ni was increased by 8.8%, Cr was increased by 8.2% than that of the Ni-Cr alloy.
Conclusion
From these results, at the 5 mm distance from the soldering point, the surface of the infrared welding was more smoother than that of the gas-oxygen torch soldering. On the EPMA analysis, the component of the specimens with infrared welding was more similar than that of the gas-oxygen torch soldering compared with the component of the Ni-Cr alloy.
Figures and Tables
Fig. 2
A: Test specimen according to ISO 9333 for castiong alloy, B: The cating specimen, C: The specimen cut with low speed carborundum disc, D: The specimen cut with low speed carborundum disc.
Fig. 4
A: Microscopic observation at 10.0 mm distance area from soldering point (×100), B: Microscopic observation at 5.0 mm distance area from soldering point (×100, White arrows denote crack lines on the specimen), C: Microscopic observation at soldering point (×100, White arrows denote crack lines on the specimen).
Fig. 5
A: Microscopic observation at 10.0 mm distance area from soldering point (×100), B: Microscopic observation at 5.0 mm distance area from soldering point (×100), C: Microscopic observation at soldering point (×100, White arrows denote crcak lines on the specimen).
Fig. 6
A: The result of EPMA analysis of Ni-Cr alloy, B: The result of EPMA analysis from 10.0 mm distance area in the gas-oxygen soldering point, C: The result of EPMA analysis from 5.0 mm distance area in the gas-oxygen soldering point, D: The result of EPMA analysis in gas-oxygen soldering spot area.
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