Experimental Investigation of Similar & Dissimilar Joints on Stainless Steel with TIG & MIG Welded

Now days, most of the structural fabrications possess welded joints that are produced using suitable welding technique. However, the joining of thick plates in a single pass welding is a cumbersome task to many fabricators. Likewise, the selection of welding technique, filler wire and welding condition for the similar and dissimilar welding of several metals is at the development stage. The similar and dissimilar metal joints of have been emerged as a structural material for various industrial applications which provides good combination of mechanical properties like strength, corrosion resistance with lower cost. Selections of joining process for such a material are difficult because of their physical and chemical properties. The stainless steel of similar and dissimilar material joints are very common structural applications joining of stainless steel is very critical because of carbon precipitation and loss of chromium leads to increase in porosity affects the quality of joint leads deteriorate strength. In the present study, stainless steel of grades 310 and 316 were welded by Tungsten Inert Gas (TIG) and Metal Inert Gas (MIG) welding with compound flux of 50 % SiO2 + 50 % TiO2 processes. The mechanical behavior like hardness, tensile strength and bending properties of similar and dissimilar metal joints were investigated. Keywords: Mechanical Properties, ATIG, MIG, SS310, SS316, Micro Structure.

Influence of multiple load indentation on the mechanical and material behaviour of steel cone-cylinder under axial compression

The first set of test data on axial collapse of cone-cylinder assembly having multiple load indentation (MLI) and its accompanying numerical studies is presented in this paper. Two perfect and two imperfect steel cone-cylinders were prepared in pairs. The cone-cylinder models have the following geometric parameters: cone radius of 40 mm, cylinder radius of 70 mm,wall thickness of 0.5 mm and cone angle of 16.7°. Cone and cylinder part were combined using Metal Inert Gas (MIG) welding technique. Results show that the repeatability of the experiment was good (3% for the perfect and 7% for the imperfect). Also, numerical prediction tends to reproduce the test data with good accuracy. The error between both approches ranges from 1% to -8%. Furthermore, the influence of geometric parameters are also significant in determining the collapse load of this type of structure. Finally, the worst multiple load indentation (WMLI) was explored for steel cone-cylinders assembly using different number of load indentations. Results indicate that as the number of indents increases, the sensitivity of the cone-cylinder models to imperfection also increases. However, at different imperfection amplitude, A, two regions were observed; (i) the region where cone-cylinder with N = 8 is more sensitive (A < 1.5), and (ii) the region where N = 4 produce the worst imperfection (1.5 < A ≤ 1.68).

Application of Electron Beam Welding Technique for Joining Ultrafine-Grained Aluminum Plates

The present study is the first attempt to join ultrafine-grained materials by electron beam welding. The aim of the study was to check the feasibility and effectiveness of this type of welding for thermally unstable materials. The results obtained are of high interest, while the welding did cause a decline in mechanical properties, the results were comparable to those obtained using solid-state welding, but with a significant advantage of narrower fusion- and heat-affected zones.

Exploration of Rotary Friction Welding Technique

Friction welding is a solid-state welding system which welds materials without authentic melting it. This study explores papers of different researchers on the friction welding method and it has been observed that the welding parameters like friction time; friction pressure, forge time and forge pressure highly affect properties of welded joints. The reason for this investigation is to exhort industry and the insightful world regarding advantages of revolving friction welding so the technique may be utilized in an ideal manner.

Study on Microstructure and Mechanical Properties of Laser Welded Dissimilar Joint of P91 Steel and INCOLOY 800HT Nickel Alloy

This investigation attempts to explore the weld characteristics of a laser welded dissimilar joint of ferritic/martensitic 9Cr-1Mo-V-Nb (P91) steel and Incoloy 800HT austenitic nickel alloy. This dissimilar joint is essential in power generating nuclear and thermal plants operating at 600–650 °C. In such critical operating conditions, it is essential for a dissimilar joint to preserve its characteristics and be free from any kind of defect. The difference between the physical properties of P91 and Incoloy 800HT makes their weldability challenging. Thus, the need for detailed characterization of this dissimilar weld arises. The present work intends to explore the usage of an unconventional welding process (i.e., laser beam welding) and its effect on the joint’s characteristics. The single-pass laser welding technique was employed to obtain maximum penetration through the keyhole mode. The welded joint morphology and mechanical properties were studied in as-welded (AW) and post-weld heat treatment (PWHT) conditions. The macro-optical examination shows the complete penetrations with no inclusion and porosities in the weld. The microstructural study was done in order to observe the precipitation and segregation of elements in dendritic and interface regions. Solidification cracks were observed in the weld fusion zone, confirming the susceptibility of Incoloy 800HT to such cracks due to a mismatch between the melting point and thermal conductivity of the base metals. Failure from base metal was observed in tensile test results of standard AW specimen with a yield stress of 265 MPa, and after PWHT, the value increased to 297 MPa. The peak hardness of 391 HV was observed in the P91 coarse grain heat-affected zone (CGHAZ), and PWHT confirmed the reduction in hardness. The impact toughness results that were obtained were inadequate, as the maximum value of impact toughness was obtained for AW P91 heat-affected zone (HAZ) 108 J and the minimum for PWHT Incoloy 800HT HAZ 45 J. Thus, difficulty in obtaining a dissimilar joint with Incoloy 800HT using the laser beam welding technique was observed due to its susceptibility to solidification cracking.

The Effects of In-Process Cooling during Friction Stir Welding of 7475 Aluminium Alloy

Certain age hardenable alloys such as AA7475 cannot be joined with perfection using fusion welding techniques. This requires non-conventional welding technique such as friction stir welding process to join these ‘difficult to weld’ alloys. In this study, three different cooling conditions i.e. cryogenic, sub-zero, and zero-degree Celsius temperature conditions have been analyzed to understand its impact on the welding process. In-process cooling was found to behave effectively and also enhanced the mechanical properties of the welded joints. A stable microstructure was clearly seen in the images observed under the metallurgical microscope. The weld efficiencies were found to be good in each of the samples which are indicative of a strong metallic joint. The effective cooling conditions employed had an overall positive impact on the joint.

The Evolution of the Nugget Zone for Dissimilar AA6061/AA7075 Joints Fabricated via Multiple-Pass Friction Stir Welding

AA6061 and AA7075 aluminum alloys were successfully joined by using single-pass and multiple-pass friction stir welding techniques after which the effects on the nugget zone evolution from a second overlapping pass and its welding direction, were investigated. In comparison to single-pass friction stir welding, the application of a second overlapping pass prolonged the dynamic recrystallization time, and the grains of the nugget zone became finer with increased high angle grain boundaries. Moreover, reversing the welding direction of the second overlapping pass enhanced the vertical flow of materials, increasing the strain of the friction stir welding in the nugget zone. As a result, the efficiency of the grain refinement and mixture of dissimilar materials during the second overlapping pass were significantly elevated. The tensile strength of the nugget zone was improved after the second overlapping pass due to both the grain refinement and mechanical interlocking of the AA6061/AA7075 alloys. The nugget zone, which was fabricated via the multiple-pass friction stir welding technique using an opposite welding direction, exhibited a 23% increase in yield strength as compared to the sample using the single-pass friction stir welding technique.

Sitem Pendukung Keputusan Penentuan Jurusan Pada Tingkat SMK Menggunakan Metode SMART (Studi Kasus:SMK Negeri2 Binjai)

Programs at the high school level makes it difficult students make choicesthatsuitcapabilities.Someofthefactorsthatinfluencesuchamistakeinchoosing majors went along with friends or majors trends of today and parentreferences, so that they appear remorse for students who have determined thechoice if it is not in accordance with their interests, abilities or talents. Thereforeit takes a decision support system that can perform the calculation criteria of thestudentstohelpdetermineappropriateschooldepartment.Thissystemimplements the SMART method based on the criteria of each alternative, namelytheIndonesiaNationalexamscores,theEnglishNationalexamscores,theMathematics National exam scores, the Natural SciencesNational exam scores.The result of this system is the value of knowledge for determining the directionbased on predetermined criteria. Of the 10 alternative or candidate is taken, thereis4eligible student majoring in technical light vehicle,4 eligible student majoringin bodyrepairtechniques and 2 eligiblestudentmajoring in welding technique.