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Characteristics of GTA fusion zones and heat affected zones in superalloy 713C

Abstract

In this paper, metallographic examinations, characterising microstructural changes in the 713C superalloy subjected to remelting by GTA method, are presented. In the fusion zone, precipitation of M23C6 or M6C carbides based on chromium and molybdenum was observed. Eutectic mixtures of (γ-gg′)-MxCy type with highly developed morphology were also perceived. It was found that, in the matrix areas with non-homogeneous chemical composition, the eutectic reaction γ-γ′ can occur at the temperature close to that of the precipitation of the MxCy carbides. The presence of silicon in the carbide phases can be conducive to lowering their solidification point by creating low-melting compound NbSi. Both in the fusion zone (FZ) and in the heat-affected zone (HAZ), the secondary precipitates of the Ni3(AlTi)-γ′ phase, varying in size from 50 to 100 nm, were found. The lattice mismatch factor of the γ and γ′ particles was +0.48 % to +0.71 %, which is characteristic of the coherent precipitates of the Ni3Al phase enriched with titanium. No dislocations or stacking faults were observed in the microstructure of the FZ. In the HAZ, some primary undissolved γ′ precipitates, with a part of aluminium probably replaced with niobium were observed, which raised their melting point.

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Implementation of Wavelet Denoising and Image Morphology on Welding Image for Estimating HAZ and Welding Defects Dibya

. Angrisani, L., Capriglione, D., Ferrigno, L., Miele, G. (2011). A new digital signal processing method for spectrum interference monitoring. Measurement Science Review , 11 (1), 1-8. Biswal, V., Soni, S., Jena, D. P., Kumar, R. (2008). Application of image processing in estimation of area of heat affected zone. Journal of Metallurgy and Materials Science , 50 (4), 219-225. Kizrak, A. M., Özen, F. (2011). A new median filter based fingerprint recognition algorithm. Procedia Computer Science , 3, 859

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Heat Transfer Modeling and Validation in the Case of Butt Welded Joints

Abstract

The aim of our work is to compare the results of a virtual model to measure heat transfer data for butt welded joints. The primary goal is to compare real-time measured temperature with the software simulated data. The virtual model is a copy of the real product, technically a virtual prototyping process is examined. Prior to any production process such as joining by butt welding, real process parameters are tested on the model and later by experiments. In the case of many parts, the joining process is a key technology, where knowledge of the thermal effects of welding on the microstructure in the heat affected zone and the joint are vital.

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Surface Roughness Effect in the Case of Welded Stainless Steel Corrosion Resistance

Abstract

It is known that fusion welding can cause a decrease in the corrosion resistance of the heat affected zone of unstabilized stainless steels. The reason for this problem is that the welding heat (in the heat affected zone (HAZ)) can cause chromium-carbide (Cr23C6) precipitation with the simultaneous reduction of chromium content at the local grain boundaries. The chromium content dictates the corrosion resistance level. The relationship between surface roughness and corrosion behaviour is well known. We sought to find the difference between the corrosion resistance and surface roughness relationship in the case of cold rolled stainless steel and in the case of heat treated (welding heat effect simulated) stainless steel [1-3].

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Study of Laser Welding of HCT600X Dual Phase Steels

Abstract

The effects of beam power and welding speed on microstructure, microhardnes and tensile strength of HCT600X laser welded steel sheets were evaluated. The welding parameters influenced both the width and the microstructure of the fusion zone and heat affected zone. The welding process has no effect on tensile strength of joints which achieved the strength of base metal and all joints fractured in the base metal.

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Analysis of the Effect of Ultrasonic Welding on Microstructure

Abstract

Ultrasonic welding is very useful for joining thin metal sheets [1, 2]. The effect of ultrasound on microstructure is currently not well understood because the changes produced depend very much on the welding parameters and the properties of the metal being considered. Thin sheets formed by cold rolling acquire a special grain structure. During the welding process the heat produced causes recrystallization; even where heat is not applied in the joining process the recrystallization process alters the mechanical properties within the heat affected zone (HAZ). The mechanical properties of the welded samples depend on the microstructure. In this work we analyse the ultrasonic welding effect on the joint and the HAZ [3, 4].

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Mathematical modelling of the thermal cycle in heat affected zone with three dimensional heat source models and pulsed power welding - Part I

-dimensional analytical temperature field around the welding cavity produced by a moving distributed high-intensity beam. Journal of Heat Transfer , 115, 848 - 856. 1993. Karkhin V. A. and Michailov V. G., Akatsevich V. D.: Modelling The Thermal Behaviour of Weld and Heat Affected Zone During Pulsed Power Welding. Mathematical Modelling of Weld Phenomena 4, H. Cerjak ed., The Institute of Materials, London, 1998. Benker H.: Practical use of Mathcad: Solving of Mathematical Problems, Springer-Verlag, Berlin-Heidelberg, 1999

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Bead-On-Plate Welding on S235JR Steel by Underwater Local Dry Chamber Process

Abstract

The article presents the results of the effect of parameters of underwater local dry chamber welding on the properties of padding welds. The effect of heat input and the type of shielding gas on the structure and hardness of welds was established. the functions for estimating the maximum hardness of the heat affected zone have been also elaborated

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Investigation of Imperfections Formed at the Ultrasonic Welding of Copper Sheets

Abstract

Ultrasonic welding is a very useful and simple welding process. It is suitable for establishing a joint between thin sheets and dissimilar metals with short preparation and finish work time [1]. Some welding defects were detected due to less than optimal ultrasonic welding parameters. These defects were ruptures, surface colour change and unacceptable deformations. This article aims to identify these failures and their causes.

Open access
Influence of the Welding Joint Type on Safety Properties of the Armor Steel Armox 500t

Abstract

Steels of the ARMOX class belong into a group of the fine-grained, increased strength steels, which are manufactured by the quenching and low-tempering procedure, with intensive thermo-mechanical treatment at high temperatures. Combination of the heat and mechanical treatments provides for the fine grains and exceptionally good properties of these steels, while the low-tempering enables relatively high hardness and good ballistic properties. This is why the welding of these steels can negatively affect the material properties in individual zones of the welded joint, what could lead to worsening of the material's ballistic properties, as well. The model plates were welded with the specially prescribed technology; the joints were the but-joint, corner joint and the joint with the shielding plate. In this paper are presented results obtained from the ballistic tests of the plates welded by the prescribed technology; tests consisted of shooting with three types of live ammunition at different types of the welded joints.

Open access