Mechanical properties of laser welded Co-Cr alloy / 대한치과보철학회지

ABSTRACT

STATEMENT OF PROBLEM: The joints of removable partial denture alloys have failed frequently after routine usage. PURPOSE: The purpose of this study was to evaluate the mechanical properties of the laser welded Co-Cr alloys. MATERIAL AND METHOD: For this study, 20 Co-Cr specimens were casted and 10 of them were seperated on the middle area and laser welded with Alpha laser welding machine(Siro Lasertec, Pforzheim, Germany). Rest of them which were as cast, were used as a control group. For the section of the experimental specimens, wire cutting machine was used to make a even gap of the all specimens. Laser welding was done with manufacturer's instrunction and tested each specimen by Instron Machine. Tensile strength, 0.2% yield strength and % elongations were recorded. Fractured surfaces were investigated with SEM. RESULTS: The results were as follows 1. The tensile strength of the laser welded group(617.7MPa) was about 75% of the as cast group(820.4MPa). It had stastically singnificant diffrences(p<0.05). 2. The % elongation of the experimental group was 6.6 which was lower than the control group(14.3). 3. Fracture of the experimental group occured in the welded surface and showed many voids. In contrast, the fracture surface of the control group was showed rough surfaces without any voids. CONCLUSION: The tensile strengths of the as-cast joints were higher than those for the laserwelded joints, and the % elongation of the experimental group was lower than the control group. Porosity was found in laser-welded joints.