Welded Joints

Bu çalışmada asıl amaç, düşük alaşımlı yüksek mukavemetli çeliklerin kaynağında kullanılan bazik elektrotların, eksi sıcaklıklardaki darbe direncini arttırmak ve CTOD testi ile incelenmesidir.
Bilindiği üzere elektrik ark kaynağı en üniversal kaynak yöntemidir. Bu çalışmamızda kaynak yöntemi olarak örtülü elektrik ark kaynağı kullanılmıştır. Kaynak için doğru akım seçilmiştir. Örtülü elektrotların kaynak bölgesine oldukça fazla yararı bulunur. Kaynak arkını ve malzemeyi diğer gazlardan korur. Çalışmada bazik elektrot kullanılmasının sebebi; bazik elektrotlar düşük alaşımlı yüksek mukavemetli çeliklerin kaynağında ve eksi sıcaklıkta kullanılan donanım yapılarının kaynağında da kullanılmasıdır. Her iki şartı da iyi şekilde sağlar ve güzel kaynak dikişleri verir.
S355 JR çeliğinin GeKa Tempo B 65 bazik elektrotu ile kaynak yapılmasıyla oluşan kaynak dikişinin mekanik özelliklerini ve darbe direncini incelemek amacıyla çekme, çentik darbe ve CTOD testleri yapılmıştır. Si miktarı azaltılan 6357 kodlu elektrot, üç numuneye de uygulanan yükler arasında en yüksek yüke dayandığı gözlemlenmiştir. Bu direnç karşısında diğer elektrotlara göre çatlağın büyümesine daha az izin vermiştir. CTOD test sonucunun, çentik darbe deney sonucu ile paralellik gösterdiği gözlemlenmiştir. En iyi çentik darbe direncine sahip olan Si miktarı azaltılan 6357 kodlu elektrot, CTOD testinde de en iyi CTOD değerine sahip olmuştur.

In the present review article, the research and progress in tungsten inert gas (TIG) and metal insert gas (MIG) welding of different materials are critically reviewed from different perspectives. Gas tungsten arc welding have been used to investigate the weld-ability of high strength alloys. Some important process parameters of TIG and MIG welding and their effects on weld quality are discussed. The mechanical properties of welded joints such as tensile strength, hardness, and other important structural properties are also reviewed. The aim of this research paper is to review the recent progress in TIG and MIG weldments of different materials and to provide a basis for follow-on research.

Metal inert gas welding is one of the important joining processes in the industry. There is wide range of applications of MIG welding to join similar as well as dissimilar materials. This process is also employed for thickness of sheets from lower to higher thickness. It is essential to have an appropriate quality of welded joints for each application. The quality of joints is dependent on various factors such as tensile strength of the joint, microstructure, hardness and penetration of the joint. These factors are affected by different welding input process variables or their combinations such as welding voltage, welding current, wire feed rate, welding speed, etc. Higher quality of the joints is ensured by accurate combinations of these variables. This method to find out combination of variables such that the value of input is lower and output is higher is called an optimization. Various optimization techniques are available to finalize the parameters, which are Taguchi DOE, Taguchi Grey based, ANN network, surface response methodology, regression analysis, mathematical modeling, etc. In this paper weight age of input variables, output variables and optimization technique is discussed per literature. The study is limited for Carbon steel sheets having thickness up to 6mm. Based on the weight age the parameters and method of optimization is suggested. An overview of various techniques of optimization have been studied, effects of different parameters on the quality output parameters are discussed and appropriate range is suggested based on the literature review. I. INTRODUCTION MIG welding [8] can be used as a manual welding operation as well as automatic process. Main advantage of the MIG welding is automatic continuous feeding filler wire. It can also be used to join unalloyed steel, aluminum alloy and stainless steels. Robotic MIG welding is found to be a very effective tool to attain required quality, higher productivity, better working condition, and semiskilled operators can cooperate. MIG welding [35] can be operated manually as well as in automatic way. The use of robotic welding increases the productivity and the quality of the welded joints. Semiskilled operator can operate the machine. But operator should have a proper knowledge of programming of the machine. Specific design of work piece, equipment, shielding gas, electrode size and type of equipment are discussed in this study. Due to flexibility [6] and higher speed, the MIG welding is one of the widely used processes among all the welding processes. Input process parameters such as weld current, voltage and preheat temperature are optimized in order to attain output properties such as tensile strength and percentage elongation. Here grey based Taguchi analysis is used to optimize the parameters and mathematical equation is formed by using a Regression analysis. Results shows that preheat temperature are most affecting factors on the tensile strength. Quality of the welded joints [2] can be measured in terms of bead geometry. There are many input process parameters of MIG welding which affects this quality of weld. Here in order to optimize the different process parameters such as weld current, work piece thickness, voltage and wire feed rate, the Taguchi optimization is used with L27 array. For the same result, mathematical model was also developed. Voltage and weld current affects most on quality. Different input parameters [10] such as welding current, voltage, and welding speed are optimized to attain the output parameters such as fatigue strength, microstructure and its related properties. MIG welding with above parameters is carried out for joining of various similar and dissimilar metals. Results show that MIG welding can be applied to many similar and dissimilar materials. Input parameters of the TIG [21] welding such as current, time, speed, variation of oxide fluxes, electrode diameter and gas flow rate are optimized by using L9 orthogonal array in Taguchi technique in order to improve the output properties such as tensile strength, hardness and depth of weld.[29] Many input parameters of MIG welding are affected on the quality output parameters of a welded joint such as welding bead geometry, distortion, different mechanical properties and penetration. Now a day different techniques of optimization such as design of experiments, network analysis and algorithm is adopted by many researcher. The weld bead dimension [39] and bead mechanical

Resistance spot welding (RSW) is considered as the dominant process for joining similar and dissimilar sheet metals in automotive industry. In this paper will be present the strength analyses of spot weld joint and analyse the transition between interfacial and pull-out failure modes for resistance spot weld joints of aluminium and austenitic stainless steel sheet, during the tensile–shear test, by usage analytical and experimental approach. For experimental testing, the specimen of 1 mm and 2 mm thickness were used, welded with different welding parameters.

The main goal of this paper is to give an example of how numerical FEM simulation in combination with parametric design features can be used very effectively in estimating stress in welded joints on pressure vessels. In order to achieve this goal, authors choose a specific pressure vessel design for compressed air in accordance with specialised literature. A complex analytical calculation was conducted followed by a numerical simulation in the CATIA V5 software. All parts of the pressure vessel were designed with the parametric design feature that the CATIA V5 software offers. In this way, quick design changes where possible. Authors choose 3 different versions of the same pressure vessel where the geometry was modified to find the best possible solution. Also, welded joints were simulated as a single part using the more common basic workbenches of the CATIA V5 software environment instead of specialised welding workbenches which cost extra. Finally, a summarize in form of a diagram is given where analytical and numerical results are compared. The paper concludes with a analyze of analytical and numerical results by estimating the error from the numerical simulation and giving guidlines for further investigation.

Abstract Redistribution of residual stress during crack growth in butt welded joint of Al5083-H111 was studied. Furthermore, the effect of post weld heat treatment and removing the weld reinforcements on fatigue crack growth rate was investigated. Three dimensional simulations of welding process and fatigue crack growth were conducted. It was shown that removing the weld reinforcements causes an increase in the residual stress. A correlation between the fatigue crack growth rate data of welded joints can be obtained with that of the parent metal by considering the weld geometry and redistribution of residual stresses in calculation of stress intensity factor.

This work analyses the influence of geometry, residual welding stresses and secondary bending effects on the fatigue strength of fillet welded joints made of structural steels. Joints with main plate thicknesses ranging from 10 to 100mm subjected both to axial and to bending load with load ratios between −1 and 0.1 were considered. The experimental results were taken from the

Redistribution of residual stress during crack growth in butt welded joint of Al5083-H111 was studied. Furthermore, the effect of post weld heat treatment and removing the weld reinforcements on fatigue crack growth rate was investigated. Three dimensional simulations of welding process and fatigue crack growth were conducted. It was shown that removing the weld reinforcements causes an increase in the residual stress. A correlation between the fatigue crack growth rate data of welded joints can be obtained with that of the parent metal by considering the weld geometry and redistribution of residual stresses in calculation of stress intensity factor.