Dimensional change of laser-welded gold alloy induced by heat treatment.
OBJECTIVE
This study examined the effects of laser welding and heat treatment on the dimensional change of cast gold alloy frameworks.


METHODS
Pairs of cast gold alloy plates were matched, fixed in a jig, and welded in a laser-welding machine at constant welding parameters. The specimens were welded unilaterally (on one surface) or bilaterally (on two surfaces) with five spots as follows: two ends fixed/unilaterally welded (A); two ends fixed/bilaterally welded (AA); one end fixed/unilaterally welded (B); two ends fixed/welded on one surface and then one end fixed/welded on the opposite surface (AB); or one end fixed/bilaterally welded (BB). The dimensional change was determined by measuring the gap between the jig base and one end of the specimen after each welding application. Dimensional change was also measured after two different heat treatments (softening and hardening). The results were analyzed using a two-way ANOVA and Duncan's test (p < 0.05).


RESULTS
The dimensional change of the specimens fixed at only one end on either surface (AB, B, and BB) was higher compared with the two ends-fixed specimens (A and AA) after laser welding. The heat treatments also increased the dimensional change in all groups except for the B group. The dimensional change was similar for each fixing method between the two types of heat treatment.


CONCLUSIONS
The method of fixing the specimens in the jig significantly affected the amount of dimensional change of the gold alloys. The heat treatments of the laser-welded specimens increased the dimensional change by releasing the residual stress.
Watanabe
Ikuya
I
Department of Biomaterials Science, Baylor College of Dentistry, Texas A&M University System Health Science Center, Dallas, TX 75246, USA. iwatanabe@bcd.tamhsc.edu
Chang
Jennifer
J
Chiu
Yvonne
Y
D012994:Dental Soldering / Q000009:adverse effects*; D006047:Gold Alloys / Q000737:chemistry / Q000528:radiation effects*; D006358:Hot Temperature; D007834:Lasers / Q000009:adverse effects*
D006047:Gold Alloys