Advanced Materials Research Vols. 622-623

Abstract: This paper has proposed a new shape of the twin-web turbine disc. Based on a design optimization of the shape of the twin-web turbine disc by finite element numerical calculation, we analyzed welding types and carried out the simulation of the welding process and obtained the residual stress. Finally we got a 5.8% weight loss and summarized residual stress of the welding and proved the feasibility of the new shape.

Abstract: The quality of joining has assumed a greater role in fabrication of metal in recent years, because of the development of new alloys with tremendously increased strength and toughness. Submerged arc welding is a high heat input fusion welding process in which weld is produced by moving localized heat source along the joint. The weld quality in turn affected by thermal cycle that the weldment experiences during the welding. In the present study a simple comprehensive mathematical model has been developed using a moving heat source and analyzing the temperature on one section and then the temperature distribution of other section are correlated with time delay with reference analyzed section.

Abstract: In this paper, the Taguchi method coupled with desirability function approach is used for the optimization of response parameters in submerged arc welding (SAW). Desirability function (DF) approach has been introduced to convert the multi- response objective to single objective. Weld quality is greatly influenced by the weld parameters which directly or indirectly affect the response parameters. In the present investigation three process variables viz. Wire feed rate (W_f), stick out (S_o) and traverse speed (T_s) have been considered and the response parameters are hardness (H), tensile strength (TS), toughness (IS). Finally a confirmatory test has been carried out with the optimal process parameters for validation of the experiment.

Abstract: Friction stir welding (FSW) process is a solid state welding process in which the material being welded does not melt or recast. This process uses a non-consumable tool to generate frictional heat in the abutting surfaces. The welding parameters and tool pin profile play major roles in deciding the weld quality. In this investigation, an attempt has been made to understand effects of process parameters include rotation speeds, welding speeds, and pin diameters on al.uminum weldment using double shoulder tools. Thermal and tensile behavior responses were examined. In this direction temperatures distribution across the friction stir aluminum weldment were measured, besides tensile strength and ductility were recorded and evaluated compared with both single shoulder and aluminum base metal.

Abstract: The heat treatable aluminium alloy AA7075 is used extensively in the aircraft industry because of its high strength to weight ratio and good ductility. In this present study the effect of process parameters on the mechanical and micro-structural properties of AA 7075 joints produced by friction stir welding was analyzed. The two sheets, aligned with perpendicular rolling directions, have been welded successively. The welded sheets have been tested under tension at room temperature in order to analyze the mechanical response with respect to the parent materials. Effects of welding speed and fixed location of base metals on microstructures, hardness distributions, and tensile properties of the welded joints were investigated. Optical microscope and SEM analysis revealed that the stir zone contains a mixed structure and onion ring pattern with a periodic change of grain size as well as a heterogeneous distribution of alloying elements. The maximum tensile strength was achieved for the joint produced at rotation speed of 800rpm and a welding speed of 20 mm/s.

Abstract: In this research work, an attempt has been made to study the weldability of AISI 304L using filler materials ENiCu-7 and ENiCrMo-3 by Gas Tungsten Arc Welding (GTAW) process. Investigations are carried out on the metallurgical and mechanical properties of AISI 304L weldments. Further, cyclic hot corrosion studies are performed on the various zones of the weldment in air oxidation for 50 cycles at 600^ C. Thermogravimetric data is collected at the end of every cycle and the weldments are characterized using XRD analysis.

Abstract: Aluminum magnesium alloys 5052 grade are also attractive in these fields due to their lower density and high specific strength. Therefore, it can be expected that the joining of aluminum alloys and magnesium alloys needs to be solved in industrial application. This research was study the effect of resistance spot welding (RSW) parameter on mechanical properties and macro structure. The specimen was aluminum magnesium 5052 grade sheet of 1 mm thickness. This experimental study aims at 2³ factorial design optimizing various RSW parameters including welding current at 14,500 and 15,500 amp, welding time at 50 and 60 cycle and electrode force were set at 1.2 and 2.2 kN. The welded specimens were tested by tensile shear testing according to JIS Z 3136: 1999 and macro structure testing according to JIS Z 3139: 1978. The result showed that both of welding current, welding time and electrode force had interaction on tensile shear and nugget size at 95% confidential (P value < 0.05). Factors affecting the optimum were welding current of 14,500 amp. , welding time of 60 cycle and electrode force of 1.2 kN. This research can bring information to the foundation in choosing the appropriate parameters to RSW process.

Abstract: The aim of the paper is to find the dependency of tool life on the cutting speed at investigation of two selected tools with linear cutting edge not parallel with the workpiece axis. The tools differ in their geometry. Conditions of experiments, used equipments and some problems, which are necessary to solve from the standpoint of machining technology with regard to tools are described in the article, too. The experimental obtained data were statistical processed by the method of regression analysis. The results are arranged into the graphical presentation, which enables the comparison of tool life at the same cutting speed and consequently the choice of the most suitable geometry of tool at the machining in specific conditions.

Abstract: The paper deals with the experiments realized by means of cutting tool with linear cutting edge not parallel with the axis of the workpiece in order to be observed the suitable values of surface roughness characteristics in dependency on the feed and cutting speed. During experiments were machined three types of steels. Acquired data were statistical processed by regression analysis. The results of the measurements show that the investigated cutting tool enables to secure the same values of surface profile characteristics of steels as a classical cutting tool at finishing with the significant increase of the feed per revolution. It directly influences length of the technological operation time which is several times shortened and so the machining productivity can increase.

Abstract: A wavelength scanning interferometry system for fast areal surface measurement of micro and nano-scale surfaces which is immune to environmental noise is introduced in this paper. It can be used for surface measurement of discontinuous surface profiles by producing phase shifts without any mechanical scanning process. White light spectral scanning interferometry, together with an acousto-optic tuneable filtering technique, is used to measure both smooth surfaces and those with large step heights. An active servo control system is used to serve as a phase compensating mechanism to eliminate the effects of environmental noise. The system can be used for on-line or in-process measurement on a shop floor.