激光焊,脉冲氩弧焊,电子束焊焊接钛材机械性能的比较

目的：比较激光焊、电子束焊、脉冲氩弧焊焊接钛的机械性能，寻求一种高质量的牙科焊钛方式。方法：采用Ｉｎｓｔｒｏｎ万能拉伸实验机测试焊接区的拉伸负荷、屈服负荷，计算伸长量，用扫描电子显微镜观察断口情况，用金相显微镜观察焊接区的金相变化，并测量焊接区的显微硬度。结果：激光焊钛的拉伸负荷与电子束焊、脉冲氩弧焊无明显区别；激光焊Ｔｉ－６Ａ１－４Ｖ的拉伸负荷与脉冲氩弧焊、电子束焊及原材料无明显区别。激光焊接区的显微硬度及热影响区最小，脉冲氩弧焊的显微硬度及热影响区最大。结论：激光焊接较脉冲氩弧焊及电子束焊更适用于牙科焊接钛。     

激光焊、钎焊焊接镍铬合金的比较研究

目的 :比较激光焊、钎焊焊接牙科镍铬合金的机械性能 ,寻求一种高质量的焊接镍铬合金的方法。方法 :采用三点弯曲试验测试焊接区的弯曲强度 ,用扫描电镜进行断口分析 ,用显微硬度计测量焊接区的显微硬度 ,用金相显微镜观察焊接区的金相变化。结果 :随着激光功率的增加 ,弯曲强度随之增加 ,当功率为 10 .5 0J/P时与母材接近而无差别 (P >0 .0 5 ) ,但明显强于钎焊 (P <0 .0 1) ,激光焊接区显微硬度略有提高 ,热影响区大约 1mm左右。结论 :激光焊接焊点强度高 ,明显优于传统的牙科钎焊 ,更适用于牙科焊接。     

激光功率对纯钛焊件机械性能的影响

目的:研究激光功率对纯钛焊件机械性能的影响,为临床应用激光焊钛提供参考。方法:采用3种不同的激光功率对纯钛进行焊接,通过测定焊件的机械强度,并进行断口扫描电镜观察和熔合区金相分析,研究激光功率与焊件强度的关系。结果:纯钛1.4kW组焊件未焊透,1.6kW和1.8kW组焊件在最大抗拉、抗弯强度上无显著差异;微观分析显示焊接接头有裂纹和气孔,以气孔为主,并且随着功率的升高,裂纹和气孔有加重的趋势。结论:激光焊接纯钛时,不能单纯以提高功率来增加熔深,避免采用过大的焊接功率。     

铸造纯钛激光焊接熔焊区的组织结构研究

目的研究激光焊接铸造纯钛时不同的焊接间距对纯钛组织结构的影响。方法将铸造钛试样按照焊接间距的大小分为4组：0.00 mm、0.25 mm、0.50 mm及1.00 mm组,将每根试样从中间断开,用牙科专用激光焊接机进行焊接。焊接后,肉眼观察焊缝区外观、显微硬度仪上测试焊区的维氏显微硬度,并对焊缝区进行金相学的观察。0.00 mm组为对照组。结果各实验组焊缝区肉眼外观形貌、显微硬度变化无明显差异。随着焊接间距的增大,热影响区增大。热影响区的金相结构均为细小的针状马氏体结构。结论焊接间距不同,焊缝处热影响区的宽度不同,但其组织结构无明显不同。     

激光焊接牙科钛材技术的研究现状

钛及钛合金具有良好的生物相容性，优良的综合性能，因此在牙科领域广泛应用于种植义齿、可摘局部义齿、金属烤齿、附着体义齿等。故采用一种高效的焊接方法对上述修复体的制作及缺陷的修补有着重要的意义．本文就激光焊接牙科钛材的焊接设备、焊接基础理论、临床应用、影响焊件质量因素、焊件质量评价及激光焊接和其他焊接方法的比较等作一综述，希望对临床工作有所帮助。     

激光焊接牙科钛材技术的研究现状

钛及钛合金具有良好的生物相容性,优良的综合性能,因此在牙科领域广泛应用于种植义齿、可摘局部义齿、金属烤齿、附着体义齿等.故采用一种高效的焊接方法对上述修复体的制作及缺陷的修补有着重要的意义.本文就激光焊接牙科钛材的焊接设备、焊接基础理论、临床应用、影响焊件质量因素、焊件质量评价及激光焊接和其他焊接方法的比较等作一综述,希望对临床工作有所帮助.     

激光焊接技术改进对衔铁焊接质量影响的实验研究

目的:探讨激光焊接技术的改进对磁性附着体衔铁与基桩焊接质量的影响,为临床应用提供实验依据.方法:采用Nd:YAC激光点焊机,以牙科高熔钴铬合金为基体金属对W600型磁性附着体成品衔铁进行焊接.试件分3组,分别作焊接面坡口和无坡口的设计以及不同焊接参数的设置.对焊接后3组试件的表面、显微结构、纵剖面等进行观察,比较焊接质量.结果:坡口组焊接深达全层,焊接缺陷较少;无坡口组焊接深度较浅.3组试件均未发现明显的热影响区以及过高显微硬度的淬硬组织.结论:焊接面的坡口设计,增加了焊接深度,提高了焊接质量.本实验条件下所增加的激光强度有利于焊接质量的提高.     

激光功率对钴铬合金及镍铬合金焊件机械性能的影响

目的:探讨不同激光功率对钴铬合金、镍铬合金焊件机械性能的影响。方法:采用临床上最常用的的2种合金进行不同功率的激光焊接,通过测定焊件的机械强度,并进行断口扫描电镜观察、熔合区金相分析和显微硬度测试,研究激光功率与焊件强度的关系。结果:钴铬合金焊件随着激光功率的增大,最大抗拉强度增大,抗弯强度则有下降的趋势;镍铬合金4组试件的最大抗拉、抗弯强度无显著差异;微观显示随着功率的增大,裂纹和气孔有增多的趋势;熔合区的显微硬度比母材高,随着功率的增大,显微硬度增大的区域增宽。结论:合适的激光功率是取得理想激光焊接接头的关键。     

激光焊接不同间距钴铬合金焊件疲劳强度的研究

目的: 探讨不同焊接间距对激光焊接钴铬合金试件机械强度和疲劳强度的影响。方法: 将牙科钴铬合金铸件采用激光焊接法分别在0.00 mm、0.25 mm、0.50 mm 3种焊接间距下焊接成哑铃形试件(n=10),以未焊接组作为对照,在材料测试机上进行三点弯曲试验,记录试件的最大压应力值和疲劳强度,并对断口进行显微晶相分析。结果: 各焊接组的最大压应力值和疲劳强度均小于未焊接组(P<0.05),3个焊接组的最大压应力值差别无显著性;在焊接组中0.25 mm组具有最佳的疲劳强(P<0.05),0.00 mm组和0.50 mm的差异无显著性。结论: 激光焊接焊件之间保留一定间隙有助于提高钴铬合金焊件的疲劳强度,焊接间隙在0.25 mm左右为宜。     

激光焊熔焊区力学性能及热反应区组织结构的变化

目的：测试和分析不同激光焊接条件下3种不同材料的焊接度、强度和热反应区组织结构的变化,方法：对钴铬合金、镍铬合金、纯钛3种测试棒采用不同电压和脉冲持续时间焊接,与对照组进行比较分析。结果：电压与钴铬合金、镍铬合金的焊接深度和强度呈正比,均值为：250v时335MPa-330v时573MPa。热反应区晶粒生长小,激光束终点呈山峰状,中心留有焊接空白区。电压与纯钛的焊接深度呈正比,其其强度呈反比,均值为：250v时221MPa-330v时154MPa。热反应区晶粒生长较大,伴有相变体膨胀,晶间氧化,组织呈蜂窝状改变。结论：激光对钴镍合金,镍铬合金的焊接性能优良,但对铸造后的纯钛焊接性能有待进一步探讨。     

FRACTURE STRENGTH OF DIFFERENT SOLDERED AND WELDED ORTHODONTIC JOINING CONFIGURATIONS WITH AND WITHOUT FILLING MATERIAL

The aim of this study was to compare the mechanical strength of different joints made by conventional brazing, TIG and laser welding with and without filling material. Five standardized joining configurations of orthodontic wire in spring hard quality were used: round, cross, 3 mm length, 9 mm length and 7 mm to orthodontic band. The joints were made by five different methods: brazing, tungsten inert gas (TIG) and laser welding with and without filling material. For the original orthodontic wire and for each kind of joint configuration or connecting method 10 specimens were carefully produced, totalizing 240. The fracture strengths were measured with a universal testing machine (Zwick 005). Data were analyzed by ANOVA (p=0.05) and Bonferroni post hoc test (p=0.05). In all cases, brazing joints were ruptured on a low level of fracture strength (186-407 N). Significant differences between brazing and TIG or laser welding (p<0.05, Bonferroni post hoc test) were found in each joint configuration. The highest fracture strength means were observed for laser welding with filling material and 3 mm joint length (998 N). Using filling materials, there was a clear tendency to higher mean values of fracture strength in TIG and laser welding. However, statistically significant differences were found only in the 9-mm long joints (p<0.05, Bonferroni post hoc test). In conclusion, the fracture strength of welded joints was positively influenced by the additional use of filling material. TIG welding was comparable to laser welding except for the impossibility of joining orthodontic wire with orthodontic band.     

Evaluation of anodic behavior of commercially pure titanium in tungsten inert gas and laser welds

Purpose: This study evaluated the resistance to corrosion in welds made with Tungsten Inert Gas (TIG) in specimens made of commercially pure titanium (cp Ti) in comparison with laser welds. Materials and Methods: A total of 15 circular specimens (10‐mm diameter, 2‐mm thick) were fabricated and divided into two groups: control group—cp Ti specimens (n = 5); experimental group—cp Ti specimens welded with TIG (n = 5) and with laser (n = 5). They were polished mechanically, washed with isopropyl alcohol, and dried with a drier. In the anodic potentiodynamic polarization assay, measurements were taken using a potentiostat/galvanostat in addition to CorrWare software for data acquisition and CorrView for data visualization and treatment. Three curves were made for each working electrode. Corrosion potential values were statistically analyzed by the Student's t‐test. Results: Statistical analysis showed that corrosion potentials and passive current densities of specimens welded with TIG are similar to those of the control group, and had lower values than laser welding. TIG welding provided higher resistance to corrosion than laser welding. Conclusion: Control specimens welded with TIG were more resistant to local corrosion initiation and propagation than those with laser welding, indicating a higher rate of formation and growth of passive film thickness on the surfaces of these alloys than on specimens welded with laser, making it more difficult for corrosion to occur.     

钛的氩弧焊、激光焊和等离子弧焊的实验研究

采用氩弧焊，激光焊和离子弧焊焊接钛支架杆，与母材对照，测试其力学性能，等测试数据经统计学处理，结果显示：钛的氩弧焊，激光焊基本满足修复体焊接要求，为进一步临床应用提供实验基础。     

Influence of different brazing and welding methods on tensile strength and microhardness of orthodontic stainless steel wire

The aim of this study was to compare the mechanical strength and microhardness of joints made by conventional brazing and tungsten inert gas (TIG) and laser welding. A standardized end-to-end joint configuration of the orthodontic wire material in spring hard quality was used. The joints were made using five different methods: brazing (soldering > 450 degrees C) with universal silver solder, two TIG, and two laser welders. Laser parameters and welding conditions were used according to the manufacturers' guidance. The tensile strengths were measured with a universal testing machine (Zwick 005). The microhardness measurements were carried out with a hardness tester (Zwick 3202). Data were analysed using one-way analysis of variance and Bonferroni's post hoc correction (P < 0.05). In all cases, brazing joints ruptured at low levels of tensile strength (198 +/- 146 MPa). Significant differences (P < 0.001) between brazing and TIG or laser welding were found. The highest means were observed for TIG welding (699-754 MPa). Laser welding showed a significantly lower mean tensile strength (369-520 MPa) compared with TIG welding. Significant differences (P < 0.001) were found between the original orthodontic wire and the mean microhardness at the centre of the welded area. The mean microhardness differed significantly between brazing (1.99 GPa), TIG (2.22-2.39 GPa) and laser welding (2.21-2.68 GPa). For orthodontic purposes, laser and TIG welding are solder-free alternatives to joining metal. TIG welding with a lower investment cost is comparable with laser welding. However, while expensive, the laser technique is a sophisticated and simple method.     

异种金属激光焊接熔焊区的组织合金化

目的 观察不同金融之间焊接后熔焊区组织合金化情况。方法 将金铂合金，镍铬合金，钴铬合金及纯钛应用激光焊接方法相互焊接，在电镜下观察熔焊区金属元素相互混熔及合金化结构。结果 金铂-镍铬，金铂-钴铬，镍铬-钴铬合金相互焊接后熔焊区两种金属元素均呈渐进性混合，交接过度平缓，中间混熔区混熔后组织杂交均匀，晶粒增长不大，金铂-钛，镍铬-钛，钴铬-钛相互焊接后在熔焊区靠近钛界面一侧合金化组织过度不良，有明显的条索状组织存在，混熔区组织与钛金属界限清楚，高倍镜下可见混熔区靠近钛界面一侧合金化组织过度不良，有明显的条索状组织存在，混熔区组织与钛金属界限清楚，高倍镜下可见混熔区组织晶粒增大，不规则，并有裂纹产生。结论 金铂-镍铬-金铂-钴铬，镍铬-钴铬合金激光焊接后熔焊区组织合金化形成良好，而金铂-钛，镍铬-钛，钴铬-钛相互焊接后熔焊区组织合金化形成不佳。     

牙科钛金属激光焊接有限元数值模拟

目的采取有限元方法建立牙科钛金属激光焊接数字模型。方法采用造型软件构建固定桥支架三维模型,通过ANSYS有限元分析软件对焊接区域进行温度场数值模拟并分析残余应力。结果建立牙科钛金属激光焊接的三维有限元数值模拟模型。结论激光焊接牙科钛金属在焊接头的内部和表面可以产生一定的残余应力。     

Distortion of laser welded titanium plates

The distortion of laser welded titanium plates was assessed for different operating conditions of the laser welding device, and with different welding parameters (in terms of weld point and prewelding). In this study, Nd : YAG laser welding device was used to join the titanium plates. The results showed that distortion increased stepwise after each welding point along the welding zone (one-side welding), but decreased consecutively as the welding proceeded on the second side of the weld (two-side welding). In the case of one-side welding, the dependence of distortion on current and spot diameter presented maxima--due to changes in the welding pool characteristics. For two-side weld the same parameters exercised little influence on its distortion recovery, due to the effect of solidified weld pools from the first side. Current and spot diameter determined the weld pool, which in turn regulated distortion based on shrinkage. Four-point prewelding significantly decreased the final distortion for both one- and two-side welds. Alternating two-side welding of prewelded assembly showed lower distortion than a classic two-side weld.     

齿科纯钛金属激光焊接工艺的探讨

目的探讨激光焊接齿科钛金属的最佳工艺参数。方法在不同参数条件下焊接齿科纯钛,测试其接头力学性能并进行接头微观组织结构分析。结果保持光斑直径为0.7 mm、脉冲持续时间3.2 ms,激光功率为1.6 kW时,获得接头的性能较佳。微观断口扫描电镜观察和熔合区金相分析得出:接头组织致密,晶粒细小,未发现有夹杂和微裂纹等缺陷。结论激光焊接直经为2.0 mm钛棒时,选择合适的焊接参数可以获得良好的接头焊接性能。     

Evaluation of welded titanium joints used with cantilevered implant-supported prostheses

STATEMENT OF PROBLEM: Early failure of laser-welded titanium implant frameworks in clinical practice has prompted an investigation of the strength and durability of welded cantilevered titanium sections. PURPOSE: The purpose of this study was to determine the effect that the use of filler wire in laser welding of titanium cantilever frameworks had on the flexural strength and fatigue resistance of the welded joints. MATERIAL AND METHODS: Sixty titanium implant-supported frameworks with 12-mm cantilevers were fabricated in 4 groups (n=15), using 3 different laser welding protocols with 0, 1, and 2 weld passes with filler wire, and 1 conventional tungsten inert gas welding method. The volume of filler wire used (mean volumes 0, 1.7, 3.4, and 8.3 mm(3)) was determined by measurement of the length of wire before and after welding each joint. Ten frameworks from each group were tested for ultimate flexural strength by loading the cantilevers 10 mm from the abutment. The remaining 5 frameworks from each group were similarly tested under a simulated masticatory load of 200 N until failure, or to 1 million cycles. A 2-way analysis of variance was used to examine the flexural strengths, and log-rank statistics were applied to cyclic test data (alpha=.05). RESULTS: There were significant differences between the 4 groups for ultimate flexural strength (P<.001) and resistance to cyclic loading (P=.002). The volume of filler wire added was a significant predictor of ultimate flexural strength (P=.03), and was a borderline determinant of the number of cycles to failure at 200 N (P=.05). Each laser weld pass with filler wire roughly doubled the ultimate flexural strength and fatigue resistance of the joint relative to the previous weld. Tungsten inert gas welding with efficient argon shielding deposited the most filler wire and produced the strongest and most fatigue-resistant joints. CONCLUSION: The ultimate flexural strength and fatigue resistance of cantilevered joints in laser-welded titanium prostheses are improved by the use of filler wire. Tungsten inert gas welding with efficient argon shielding can be used in situations when a high-strength joint is required.