Optimizing the Pulsed Current Gas Tungsten Arc Welding Parameters

The selection of process parameter in the gas tungsten arc （GTA） welding of titanium alloy was presented for obtaining optimum grain size and hardness. Titanium alloy （Ti-6Al-4V） is one of the most important non-ferrous metals which offers great potential application in aerospace, biomedical and chemical industries, because of its low density （4.5 g/cm^3）, excellent corrosion resistance, high strength, attractive fracture behaviour and high melting point （1678℃）. The preferred welding process for titanium alloy is frequent GTA welding due to its comparatively easier applicability and better economy. In the case of single pass （GTA） welding of thinner section of this alloy, the pulsed current has been found beneficial due to its advantages over the conventional continuous current process. Many considerations come into the picture and one needs to carefully balance various pulse current parameters to reach an optimum combination. Four factors, five level, central composite, rotatable design matrix were used to optimize the required number of experimental conditions. Mathematical models were developed to predict the fusion zone grain size using analysis of variance （ANOVA） and regression analysis. The developed models were optimized using the traditional Hooke and Jeeve＇s algorithm. Experimental results were provided to illustrate the proposed approach.

Experimental investigation of Tie6Ale4V titanium alloy and 304L stainless steel friction welded with copper interlayer

The basic principle of friction welding is intermetallic bonding at the stage of super plasticity attained with self-generating heat due to friction and finishing at upset pressure. Now the dissimilar metal joints are especially popular in defense, aerospace, automobile, bio-medical,refinery and nuclear engineerings. In friction welding, some special alloys with dual phase are not joined successfully due to poor bonding strength. The alloy surfaces after bonding also have metallurgical changes in the line of interfacing. The reported research work in this area is scanty. Although the sound weld zone of direct bonding between Tie6Ale4 V and SS304 L was obtained though many trials, the joint was not successful. In this paper, the friction welding characteristics between Tie6Ale4 V and SS304 L into which pure oxygen free copper(OFC) was introduced as interlayer were investigated. Boxe Behnken design was used to minimize the number of experiments to be performed. The weld joint was analyzed for its mechanical strength. The highest tensile strength between Tie6Ale4 V and SS304 L between which pure copper was used as insert metal was acquired. Micro-structural analysis and elemental analysis were carried out by EDS, and the formation of intermetallic compound at the interface was identified by XRD analysis.

以银为中间层扩散连接Ti-6Al-4V和304不锈钢的工艺窗口（英文）

由于钛合金具有高的化学活性,很难采用传统焊接技术进行连接。在钛合金和不锈钢熔焊过程中,钛容易与空气中的氮和氧反应形成脆性中间化合物,降低焊接接头的力学性能。因此,宜采用扩散连接钛合金。以银为中间层,研究扩散连接Ti-6Al-4V和AISI304不锈钢的工艺参数。通过搭接剪切实验和显微组织分析对接头质量进行评价。通过实验结果得到扩散连接的工艺窗口,为获得无缺陷接头工艺参数提供参考。在750-800°C时可以成功进行扩散连接。在5 MPa和90 min条件下焊接接头可获得最大搭接剪切强度。

Process Parameter Optimization of the Pulsed Current Argon Tungsten Arc Welding of Titanium Alloy

为在搏动的当前的煤气的钨弧焊获得最佳的张力的性质的进程参数的选择被介绍。张力的性质包括最终的张力的力量，收益力量和槽口张力的力量。所有这些特征被修改 taguchi 方法在进程参数的选择一起考虑在张力的性质上分析每个焊接进程参数的效果。试验性的结果被供应说明途径。

应用响应曲面法优化摩擦焊接Ti-6Al-4V和SS304L工艺参数（英文）

提出了摩擦焊接过程中近优化设置工艺参数。基于不同的输入参数,如摩擦压力、摩擦时间、顶锻压力和顶锻时间及输出参数,如拉伸强度、硬度和材料损耗,成功获得摩擦焊接工艺。采用夹层技术,通过摩擦焊接工艺,连接Ti-6Al-4V和SS304L。采用响应曲面法和Box-Behnken设计确定实验次数并证实优化工艺参数,以得到更好的接头强度。结果很令人满意。在摩擦压力为12 N/mm^2、顶锻压力为40 N/mm^2、摩擦时间为1.2 s、定锻时间为7 s的条件下,得到接头强度为523 MPa。

Effect of process parameters of pulsed current tungsten inert gas welding on weld pool geometry of titanium welds

The effects of pulsing current parameters on weld pool geometry namely front height, back height, front width and back width of pulse current gas tungsten arc welded （GTAW） titanium alloy was analysed. Four factors, five levels, central composite design were used to develop empirical relationships, incorporating pulsed current parameters and weld pool geometry.

Synthesis and characterization of high ceramic yield polycarbosilane precursor for SiC

The polycarbosilane(PCS)precursor for SiC with high molecular weight and medium molecular weight distribution was synthesized from polydimethylsilane at normal pressure.The chemical formula,the number average molecular weight,and the polydispersivity index of the synthesized PCS are SiC_(1.94)H_(5.01)O_(0.028),1135,and 1.66,respectively,which can be attributed to the higher reaction temperature used for polymerization.The polymer to ceramic conversion of PCS was completed at 900℃with a ceramic yield of 85%.The crystallization started at 1100℃,and at 1200℃,well resolved peaks ofβ-SiC were formed with small amount ofα-cristobalite.The X-ray diffraction(XRD)and transmission electron microscopy(TEM)studies indicated the presence of nanocrystallineβ-SiC.

Effect of process parameters on SPRC35 spot welded automotive panels

This paper presents an experimental study on the resistance spot weldability of SPRC35（steel plate re-phosphorised cold rolled） sheets.The sheets were joined by using resistance spot welding as lap joint.The weld nugget diameter and tensile shear force were investigated.Tensile-shear tests were applied to the welded specimens to understand the tensile shear force that the joint can withstand.Empirical relationships were developed for both nugget diameter and tensile shear force.Use of automatic mode, will increase the dependence on the use of equations to predict the nugget diameter.The developed models have been checked for their adequacy and significance by the F test and t test respectively.The results obtained from the empirical relationships have been optimized and also tested using conformity test runs.