Nd:YAG激光焊接牙科镍铬合金机械性能的研究

目的：通过评价焊接后的机械性能，探讨激光焊接牙科镍铬合金的最佳条件。方法：采用国产Nd:YAG激光器在不同的功率条件下焊接牙科镍铬合金试样，比较其抗拉强度、介长率、维氏硬度等机械性能指标，结合相应的金相学检查及断口扫描电镜分析，并与母材比较。结果：随着激光功率的增加，抗拉强度随之增加，当功率为10.5J/P时与母材接近而无差别；与原材料相比，焊接区的显微硬度略有提高；断口扫描电镜显示，焊接的最大熔深约为0.9-1.0mm，未见气孔、裂纹或其它缺陷。结论：激光焊接焊点强度高，热影响区小，穿透力较强，选择合适的焊接条件可达到理想的焊接效果。

Mechanical properties of laser welds of nickel-chromium alloy in dentistry by pulsed Nd:YAG laser apparatus

Objective The mechanical properties of laser-welded nickel-chromium alloy under different laser welding conditions were evaluated to find the optimal parameters.Methods Different laser irradiation power was used to weld dental nickel-chromium alloy by Nd:YAG apparatus. Mechanical properties, metallographic evaluation and scanning electron microscopy (SEM) analysis were used to evaluate joined samples.The mechanical properties,including tensile strength,percentage elongation and Vickers microhardness, were compared with parent samples.Results Mechanical properties was improved simply by increasing the irradiation power. Tensile strength of joined samples irradiated by laser at 10.5 Joules were similar to that of the original metal.No statistically significant difference was found between joints fused at 10.5 Joules and the parent mental.Compared with original metal,the elongation values of joined samples decreased significantly.The microhardness values increased in the welded joint region. SEM observation on fracture surface revealed that the most penetration depth was 0.9 mm to 1.0 mm.No porosities and cracks and other defects were found.Conclusion Laser welding has stronger welded joints and smaller heat-affected zone and greater penetration depth. Nd:YAG laser welding of nickel-chromium alloy could get a good result through selecting appropriate parameters.