[The effects of different welding wires on the mechanical properties of laser welding joints].
OBJECTIVE
To evaluate the mechanical properties and microstructure of laser-welded joints with different welding wires for clinical use of welding wire.


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


RESULTS
For Co-Cr alloy, the UTS of casting wire group and commercially welding wire group was respectively (606.40+/-82.53)MPa and (693.61+/-47.68)MPa; the UBS was respectively (997.95+/-88.89)MPa and (1160.76+/-91.59)MPa. ANOVA showed a significant difference of UTS and UBS between the two groups at the 0.05 level (P<0.05). For Ni-Cr alloy, the UTS of casting wire group and commercially welding wire group was respectively (558.14+/-46.75)MPa and (582.32+/-35.43)MPa; the UBS was respectively (1084.75+/-46.02)MPa and (1078.29+/-36.25)MPa. There was no significant difference between the two groups (P>0.05). SEM and metallurgical examination showed the welded zone exhibiting more cracks in the casting wire group than in the commercially welding wire group.


CONCLUSIONS
It would be advisable to work with commercially welding wire for the joints that need better strength.
Huang
Qing-feng
QF
Department of Prosthodontics, College of Stomatology, Ninth People's Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200011, China.
Zhang
Jian-zhong
JZ
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 / Q000379:methods*; D006801:Humans; D007834:Lasers; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D009532:Nickel / Q000737:chemistry; D018583:Pliability; D013718:Tensile Strength; D014896:Welding
D002858:Chromium Alloys; D003722:Dental Alloys; D003035:Cobalt; D009532:Nickel