[Effect of laser irradiation power on the mechanical properties of Co-Cr and Ni-Cr laser-welded joints.].
OBJECTIVE
To investigate the effect of different irradiation power on the mechanical properties of laser-welded joints.


METHODS
The standard tensile test and three-point bending test rods made from Co-Cr and Ni-Cr alloy were laser-welded with different irradiation powers. Then the tensile rods were tested for the ultimate tensile strength (UTS), and the bending rods for the ultimate bending strength (UBS). The tensile fracture surface was examined by scanning electron microscopy (SEM). Metallurgical analysis and microhardness test were also performed on polished longitudinal sectioned samples.


RESULTS
For Co-Cr alloy, greater irradiation power resulted in greater UTS, minor UBS. For Ni-Cr alloy, there was no significant difference of UTS and UBS between the four groups. SEM and metallurgical examination showed that the welded zone exhibited more gas pores and cracks as the irradiation power increased. Microhardness test showed that hardness increased toward the center of the welded zone and as the irradiation power increased, the range of hardness increased was expanded.


CONCLUSIONS
The optimal laser irradiation power was the key to achieved superior mechanical properties joints.
Zhang
Jian-zhong
JZ
Department of Prosthodontics, Ninth People's Hospital, School of Stomatology, Shanghai Second Medical University, Shanghai 200011, China.
Huang
Qing-feng
QF
Jiang
Wei-dong
WD
Li
Quan
Q
Yu
Jin-xing
JX
D002858:Chromium Alloys / Q000737:chemistry*; D003035:Cobalt / Q000737:chemistry; D003722:Dental Alloys / Q000737:chemistry*; D012994:Dental Soldering; D006244:Hardness; D007834:Lasers; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D009532:Nickel / Q000737:chemistry; D013718:Tensile Strength
D002858:Chromium Alloys; D003722:Dental Alloys; D003035:Cobalt; D009532:Nickel