TA15钛合金A-TIG焊接头组织和性能分析

以CaR与MgF2的混合物为活性荆，对TA15钛合金A-TIG焊接头组织和性能进行了分析，并和常规TIG焊进行了比较。结果表明：A-TIG焊能够有效减少气孔数量，提高接头的抗拉和抗弯性能；与常规TIG焊相比，A-TIG焊HAZ较窄且组织较细，而二者的焊缝区组织基本相同；活性荆的加入并没有降低A—TIG焊接头的耐腐蚀性能。     

单组分氟化物对钛合金氩弧焊电弧形态的影响

针对厚2.5mm的BT20钛合金平板,沿不同氟化物涂层进行TIG焊接工艺试验,对沿不同氟化物TIG焊接过程中的电弧形态以及焊后焊缝成形进行了研究,并与相同焊接工艺参数下的常规TIG焊进行了对比.试验结果表明,不同的单组分氟化物对焊接电弧形态的影响有较大区别,并由此总结出了电弧形态变化与焊缝熔深的关系.     

Optimization of A-TIG process parameters using response surface methodology

In the present work, the influence of process parameters such as welding current (I), welding speed (S), and flux coating density (F) on different aspects of weld bead geometry for example depth of penetration (DOP), bead width (BW), depth to width ratio (D/W), and weld fusion zone area (WA) were investigated by using the central composite design (CCD). 9–12% Cr ferritic stainless steel (FSS) plates were welded using A-TIG welding. It was observed that all input variables have a direct influence on the DOP, BW, and D/W. However, flux coating density has no significant effect on WA. Mathematical models were generated from the obtained responses to predict the weld bead geometry. An optimized DOP, BW, D/W, and WA of 6.95?mm, 8.76?mm, 0.80, and 41.99?mm², respectively, were predicted at the welding current of 213.78 A, the welding speed of 96.22?mm/min, and the flux coating density of 1.99?mg/cm². Conformity test was done to check the practicability of the developed models. The conformity test results were in good agreement with the predicted values. Arc constriction and reversal in Marangoni convection were considered as major mechanisms for the deep and narrow weld bead during A-TIG welding.     

粉煤灰/二氧化硅活性剂在Q235钢A-TIG焊中的应用

为了探究粉煤灰作为A-TIG焊活性剂的可行性,以粉煤灰和不同含量的二氧化硅制备复合活性剂在Q235钢基体表面进行A-TIG焊,研究了复合活性剂成分含量对焊缝截面形貌、显微组织和元素分布的影响.结果表明:采用粉煤灰-40%SiO_2作为复合活性剂进行A-TIG焊时,可将6 mm厚Q235钢板一次性焊透,焊缝深宽比可达到0.85;焊缝出现明显的中间收缩倾向,呈"深口杯"状,可实现单道焊双面成型的效果;其焊缝柱状晶数目较多、组织排列规则且具有方向性,熔合区和热影响区组织均匀细小,可降低焊接母材的过热倾向;相对于100%SiO_2活性剂,Si元素的溶入量和溶入深度显著增加,这说明粉煤灰中其他成分的存在对Si元素溶入焊缝、进而增加焊缝熔深起到促进作用.采用粉煤灰-40%SiO_2为活性剂进行A-TIG焊时焊缝熔深的增加机理可能是以电弧收缩理论为主,但考虑到Al元素溶入较深且溶入量较多,粉煤灰中其他物相又十分复杂,在高温电弧作用下各物相之间相互反应放热致使电弧热输入增加、其他组分在熔池中改变了熔池表面张力温度梯度等均可能致使焊缝熔深增加.     

活性化TIG焊熔深增加机理的研究

以不锈钢0Crl8Ni9为实验对象，涂敷含有Bi的SiO2和TiO2活性剂，通过1mm厚高熔点薄钨板挡住熔池流动的方法进行焊接实验．对钨板两侧Bi颗粒的分布进行了测试，分析涂敷SiO2和TiO2后熔池流动方向的变化，同时采集了电弧电压．结果表明：活性剂SiO2和TiO2改变了熔池的流动方向；SiO2使电压提高约4．2V，而TiO2对电弧电压没有影响；活性剂并未使电弧整体发生收缩，而使电弧整体发生了膨胀；SiO2使等离子体发生了收缩；电弧等离子体收缩和电弧导电通道变长是SiO2活性剂提高电弧电压的主要原因．分析认为，SiO2增加熔深是等离子体收缩、阳极斑点收缩和表面张力温度梯度由负变正共同作用的结果；TiO2增加熔深只是表面张力温度梯度由负变正的作用．     

表面活性剂对钛合金A-TIG焊熔深的影响

采用卤化物（CaF2，ZnF2，MnCl2）、氧化物（SiO2，TiO2，V2O5）和单质Te作为表面活性剂进行钛合金A—TIG焊，研究了表面活性剂对焊接熔深的影响规律。结果表明：3种卤化物都能增加焊接熔深，其中MnCl2使得焊接熔深达到传统TIG焊的2倍以上：3种氧化物对焊缝成形几乎没有影响；Te能明显增加焊接熔深，减小焊缝熔宽。认为电弧收缩是卤化物但不是Te增加钛合金A—TIG焊熔深的主要机理。     

AZ31镁合金活性TIG焊接头分析

针对AZ31镁合金材料,研究了在A—TIG焊中单一成分的活性剂对焊缝成形的影响。试验结果表明,与无活性剂的焊缝相比,活性剂TiO2、SiO2、Cr2O3、CdCl2和CaCl2能够有效地增加镁合金焊缝的熔深和深宽比。镁合金涂敷活性剂CdCl2后焊缝接头的微观组织与未涂敷时焊缝接头的微观组织没有明显区别,只是前者热影响区稍宽。未涂敷活性剂和涂敷CdCl2的试样硬度值分布相差不大。在AZ31镁合金的焊接中,活性剂CdCl2的作用效果最好。     

Optimization of Welding Process Parameters for 9Cr-1Mo Steel Using RSM and GA

Optimization of A-TIG welding process parameters for 9Cr-1Mo steel has been carried out using response surface methodology (RSM) and genetic algorithm (GA). RSM has been used to obtain the design matrix for generating data on the influence of process parameters on the response variables. A second-order response surface model was developed for predicting the response for the set of given input variables. Then, numerical and graphical optimization was performed using RSM to obtain the target depth of penetration (DOP) and heat-affected zone (HAZ) width using desirability approach. Multiple regression models were developed based on the generated data, and then the models were used in GA to determine the optimum process parameters for achieving the target DOP and HAZ width. GA-based models employed two different selection processes. Both the RSM- and GA-based models suggested a number of solutions in terms of process parameters, and the identified solutions were validated by experiments. GA-based model employing tournament selection has been found to be a more accurate method for determining the optimum A-TIG welding process parameters.     

磁场下镁合金A-TIG接头成形性及显微组织分析

在对5 mm厚的AZ31B镁合金板材进行A-TIG焊焊接过程中引入外加纵向磁场,试验所用的活性剂是以氧化物为基的活性剂,试验中改变磁场参数,对焊接接头的成形性、组织及性能进行试验和检测,研究磁场参数对镁合金A-TIG焊过程的影响规律.结果表明,活性剂及磁场共同作用可以改善焊接接头的成形性和组织形态,在磁场频率为10 Hz,磁场电流为2 A时,焊接接头的成形系数和性能得到了最佳值,此时成形系数为2.304,硬度为980.98 MPa;外加磁场通过电磁搅拌作用与活性剂相结合,改变了熔池的流行形态,使金属液由四周向中心流动并伴有搅拌,进而使焊缝熔深增大的同时细化组织,改善接头力学性能.     

焊接应力腐蚀开裂机理及A-TIG焊接抗蚀性研究

A-TIG能大幅度提高生产率,降低生产成本,同时还可以减少焊接变形,具有广泛的应用前途。对应力腐蚀开裂机理及其影响因素进行了分析,并对A-TIG焊接提高抗应力腐蚀开裂能力原因进行了研究。