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Laser Weldability of Cobalt-Chromium Alloy for Dental Use

牙科用钴铬合金的激光焊接性能

基本信息

批准号：
09672026
负责人：
KAKIMOTO Kazutoshi
金额：
$ 1.86万
依托单位：
Osaka Dental University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1998
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-09672026/
关键词：
laser welding cobalt-chromium alloy weldability

项目摘要

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.

对7种市售铸造用钴铬合金和1种加工用钴铬合金进行了脉冲YAG激光焊接性试验。结果表明：铸造用钴Chrome合金激光焊缝均出现裂纹。铸造用钴铬合金焊接后的断口为脆性断口，有凝固断口，而加工用钴铬合金激光焊接后没有裂纹产生。断口为韧性断口。激光焊接使铸造用钴铬合金硬化，而加工用钴铬合金软化。母材晶界中含有大量的钼、硅、硫和碳，通过对3种铸造用合金的化学分析，发现激光焊接裂纹产生量最大的合金中含有大量的硅、碳和磷。X射线衍射分析表明，焊缝为面心立方（fcc）结构，而母材为密排六方（hcp）结构。另一方面，用于加工的合金的母材和焊缝均为面心立方结构。铸造用合金焊缝中有大量的共晶，其成分似硅氧化物。此外，观察到铝或氧化铬和硫化钙。因此，碳、硅、硫的存在被认为是焊缝裂纹产生的原因，对含碳量少的合金进行激光焊接性的研究，发现碳的减少控制了焊缝裂纹的产生，而铝的参与导致了裂纹的产生。此外，结果证明能够通过在合金中重叠点焊来控制裂纹，并且产生少量裂纹。此外，还证明能够通过控制脉冲形状来控制焊接缺陷的产生。