Effect of welding method on joint strength of laser-welded gold alloy.
OBJECTIVE
To examine the effect of welding method and heat treatment on the strength of laser-welded gold alloy with age-hardenability at intraoral temperature.


METHODS
Cast gold alloy plates (0.5 x 3.0 x 20 mm3) were prepared and cut perpendicular to the 3.0 mm surface of the plate. After the cut halves were fixed in a jig, they were laser-welded using a Nd: YAG laser. Three laser pulses were applied from one side (single-welded) or both sides (double-welded) to weld the entire joint width of the specimens. Three different heat treatments were given the specimens: solution treatment at 700 degrees C for 5 minute (ST), aging at 250 degrees C for 15 minute after ST (HA), and aging at 37 degrees C for 3 day after ST (IA). As-cast specimens were also reserved. Uncut specimens served as non-welded control specimens. Tensile testing was conducted at a crosshead speed of 2 mm/minute and a gauge length of 10 mm. The breaking stress (Bs: MPa) was recorded, and the data (n = 5 per group) were statistically analyzed.


RESULTS
In the control groups, the Bs values of the IA were not significantly different (P > 0.05) from those of the HA specimens. The laser-welded IA specimens showed significantly greater (P < 0.05) Bs values compared to the solution-treated and as-cast specimens. The double-welded specimens showed significantly greater Bs values compared to the single-welded specimens after any heat treatment.
Department of Biomaterials Science, Baylor College of Dentistry, Texas A&M University System Health Science Center, 3302 Gaston Ave., Dallas, TX 75246, USA. iwatanabe@tambcd.edu
Ikuya
I
Watanabe
Jie
J
Liu
Mitsuru
M
Atsuta
Toru
T
Okabe
D012994:Dental Soldering / Q000295:instrumentation / Q000379:methods; D006047:Gold Alloys / Q000737:chemistry*; D006244:Hardness; D006358:Hot Temperature; D006801:Humans; D007834:Lasers; D008422:Materials Testing; D013314:Stress, Mechanical; D013718:Tensile Strength; D013997:Time Factors
D006047:Gold Alloys