ABSTRACT
The deteriorated plasticity arising from the insoluble precipitates may lead to cracks during the rolling of FeCrAl alloys. The microstructure evolution and hot deformation behavior of an FeCrAl alloy were investigated in the temperature range of 750-1200 °C and strain rate range of 0.01-10 s-1. The flow stress of the FeCrAl alloy decreased with an increasing deformation temperature and decreased strain rate during hot working. The thermal deformation activation energy was determined to be 329.49 kJ/mol based on the compression test. Then, the optimal hot working range was given based on the established hot processing maps. The hot processing map revealed four small instability zones. The optimal working range for the material was identified as follows: at a true strain of 0.69, the deformation temperature should be 1050-1200 °C, and the strain rate should be 0.01-0.4 s-1. The observation of key samples of thermally simulated compression showed that discontinuous dynamic recrystallization started to occur with the temperate above 1000 °C, leading to bended grain boundaries. When the temperature was increased to 1150 °C, the dynamic recrystallization resulted in a microstructure composed of fine and equiaxed grains.
ABSTRACT
BACKGROUND: Because of the various defects of malarplasty, including a large incision, much bleeding, visible scars after the operation, and so on, caused by the conventional coronal incision or the temporal incision with the intraoral incision approach, the malarplasty by simple intraoral approach is an innovative development. METHODS: Through the intraoral approach and subperiosteal dissection, we can reach the osteotomy point on the zygomatic body directly and arrive at the osteotomy point at the zygomatic arch end along the medial side of the zygoma. A new L osteotomy is applied with the reciprocating saw. In addition, the osteotomy was performed on the zygomatic arch from the inside out with an angle of 20 degrees horizontally. RESULTS: From 1997 to 2010, we were satisfied with the results of 114 cases of malarplasty with the intraoral approach and L osteotomy as the observed objects. There are 103 cases for women and 11 for men. Ages ranged from 16 to 48 years. The mean operation time is approximately 1 hour. We just had a few complications: 3 nonunion at the osteotomy line and needed a second surgery to repair as well as 2 slight cheek drooping during the initial period and required face lifting. CONCLUSIONS: The method of intraoral approach and L-shaped osteotomy for zygoma reduction can reduce prominent zygoma while maintaining the natural curves of the zygomatic body and arch. Because of the simple procedures, fewer complications, and excellent results, this method will be considered a relatively desirable way. LEVEL OF EVIDENCE: Therapeutic, III.
