1998 Fiscal Year Final Research Report Summary
Laser Weldability of Cobalt-Chromium Alloy for Dental Use
| Project/Area Number |
09672026
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
補綴理工系歯学
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| Research Institution | Osaka Dental University |
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Principal Investigator |
KAKIMOTO Kazutoshi Osaka Dental University, Department of Dentistry, Assistant, 歯学部, 助手 (20194681)
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| Co-Investigator(Kenkyū-buntansha) |
KOMASA Yutaka Osaka dental University, Department of Dentistry, Assistant Professor, 歯学部, 助教授 (10131385)
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| Project Period (FY) |
1997 – 1998
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| Keywords | laser welding / cobalt-chromium alloy / weldability |
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| Research Abstract |
For seven kinds of marketing cobalt-chromium alloy for casting and one alloy for processing, weldability by the pulsed YAG laser irradiation was examined. The following results were obtained.
The crack occurred in the laser weld of any cobalt chrome alloy for casting. The fracture surface of weled cobalt-chromium alloy for casting was brittle fracture surface which had fracture surface of solidification, On the other hand, no crack generated in the laser weld of the cobalt-chromium alloy for processing. The fracture surface was ductile fracture surface. The cobalt-chromium alloys for casting were hardened by laser welding, but alloy for processing was softened. There were a lot of molybdenum, silicon, sulfur, and carbon in the grain boundary of the base metal.
It turned out for the alloy with the largest crack generation in laser weld to contain a lot of silicon, carbon, and phosphorus by chemical analyze of three kinds of alloy for casting. The weld of the alloy for the casting was a face-centered cubic (fcc) structure though the base metal was a closed-packed hexagonal (hcp) structure according to the X-ray diffractometer analyze. On the other hand, both base metal and weld for the alloy for processing were fcc structures. There were many eutectics which seemed to be silicon oxide in the weld of the alloy for casting. Moreover, aluminum, or chromium oxide, and calcium sulfide were observed. Therefore, the existence of the carbon, silicon, and sulfur was thought as a cause of the crack generation of the weld.
When the laser weldability of the alloy with little carbon was examined, it turned out the reduce of carbon controlled crack generation in weld, and involvement of aluminum generated the crack. Moreover, it turned out to be able to control the crack by overlapping the spot weld in the alloy with a little crack generation. In addition, it turned out to be able to control the generation of the welding defect by controlling the pulse shape.
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Research Products
(4 results)
