Welding Metallurgy of
01 Jan 1987-
About: The article was published on 1987-01-01 and is currently open access. It has received 991 citations till now. The article focuses on the topics: Welding.
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TL;DR: In this article, a model is presented for the prediction of the post-solidification solute distribution of a single phase alloy in a fusion weld, taking into account the shape and size of the weld pool, the acceleration of growth rate as a solidifying crystal curves from the fusion boundary towards the weld centerline in an oval weld pool.
Abstract: A model is presented for the prediction of the post-solidification solute distribution of a single phase alloy in a fusion weld It takes into account the shape and size of the weld pool, the acceleration of growth rate as a solidifying crystal curves from the fusion boundary towards the weld centreline in an oval weld pool, the melting stage prior to the solidification and the diffusion in solid Temperature dependencies of diffusion coefficients are included The proposed model and analogous solidification models are categorised with a system consisting of Cases and Sub-Cases The thermodiffusional problem is solved numerically It is shown that the solid diffusion during the melting stage may essentially affect the post-solidification solute distribution near the fusion boundary Radiographical experiments on sulphur support the calculations The model is restricted to planar growth, until microsegregation is included
7 citations
Cites result from "Welding Metallurgy of"
...The model for weld pool shape and dR/dt is traditional.(2,3,10,22) The authors’ proposition of the diffusion in the solid in association with the melting stage of a fusion weld, bears resemblance to the Brody and Flemings’ solution and its derivatives (the Clyne–Kurz approach),(14,31) which is a ‘Sub-Case 2 (DS)’-type solution....
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TL;DR: In this article, the results of thermal and mechanical tests performed on precision castings made of the Inconel 713C alloy and intended for use in the production of low pressure turbine blades are presented.
Abstract: Nickel-based alloys are widely used in industries such as the aircraft industry, chemicals, power generation, and others. Their stable mechanical properties in combination with high resistance to aggressive environments at high temperatures make these materials suitable for the production of components of devices and machines intended for operation in extremely difficult conditions, e.g. in aircraft engines. This paper presents the results of thermal and mechanical tests performed on precision castings made of the Inconel 713C alloy and intended for use in the production of low pressure turbine blades. The tests enabled the determination of the nil strength temperature (NST), the nil ductility temperature (NDT), and the ductility recovery temperature (DRT) of the material tested. Based on the values obtained, the high temperature brittleness range (HTBR) and the hot cracking resistance index were determined. Metallographic examinations were conducted in order to describe the cracking mechanisms. It was found that the main cracking mechanism was the partial melting of grains and subsequently the rupture of a thin liquid film along crystal boundaries as a result of deformation during crystallisation. Another cracking mechanism identified was the DDC (Ductility Dip Cracking) mechanism. The results obtained provide a basis for improving precision casting processes for aircraft components and constitute guidelines for designers, engineers, and casting technologists.
7 citations
Dissertation•
16 Apr 2013
TL;DR: In this paper, the effects of laser surface treatment on the corrosion and wear performance for Tribaloy 800 (T800), and T800-based WC HVOF-sprayed MMC coatings onto 316L stainless steel substrate were investigated.
Abstract: Metal Matrix Composite (MMC) coatings, comprised of a hard ceramic phase embedded in a metallic matrix, are increasingly being applied for many industrial applications to provide cost effective protection against wear and corrosion. Such coatings are commonly produced by thermal spray. Although the most advanced thermal spray techniques, such as high-velocity oxy-fuel (HVOF), produce MMC coatings with total porosity levels lower than 1%, due to the nature of thermal spray MMC coatings, corrosion still takes place. The corrosion processes are dominated by the complex microgalvanic and interfacial mechanisms, as well as by porosity, due to the existence of various defects in HVOF MMC coatings. As a result, HVOF coatings do not ultimately meet the requirements in certain service conditions in operating environments. Therefore, there is a need to find a method of modification of coatings, with significantly reduced microstructural defects and improved cohesive and adhesive strength so that the service life of the coated components can be increased. This work aims to investigate the effects of laser surface treatment on the corrosion and wear performance for Tribaloy 800 (T800), and T800-based WC HVOF-sprayed MMC coatings onto 316L stainless steel substrate. Laser surface treatments have been carried out using a 1.5 kW high power diode laser. Laser operating windows for various coatings have been established for the relationships between the laser operating conditions and melt pool dimensions, in the consideration of formation of cracks and porosity within laser-treated surface layers. Microstructural analysis of the powders, and various coatings before and after laser treatments has been conducted by means of optical and SEM (with EDX) microscopy, electron probe micro-analysis (EPMA), white-light interferometery, and X-ray diffraction, to characterise morphology, chemical composition and phase. Corrosion performance of various coating was evaluated using immersion testing in 3 M H2SO4 at pH ~ 1.27 at room temperature for different periods of time (including 24, 48, 72, 96 and 168 hours), followed by Inductivity Coupled Plasma-optical emission spectrometer (ICP-OES) technique, potentiodynamic polarisation in 0.5 M H2SO4, and electrochemical impedance spectroscopy studies in 0.5 M H2SO4 solution after 1, 3, 6, 12, 24, and 48 hours. Inaddition, dry sliding wear behaviour measured by pin-on-disk and microhardness test of various coatings before and after laser treatment were evaluated.The results indicated that it was possible to achieve full control of melt depth and the degree of melting, particularly full or partial melting of WC particles by proper selection of the laser processing parameters while preventing dilution. Significant improvement of corrosion and wear resistance has been achieved after laser treatment as a result of the elimination of discrete splat-structure, removal of microcrevices and porosity, as well as the reduction of microgalvanic driving force between the WC and the metal matrix by formation of new phases at the interfaces. The degree of melting of WC particles controls the corrosion properties of the laser-treated HVOF coatings. Moreover, the results also suggested that partial melting of WC had positive effect on wear resistance of the coatings.
7 citations
Cites background from "Welding Metallurgy of"
...43 Effect of temperature gradient G and growth rate R on the morphology and size of solidification microstructure [122] ....
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...43 Effect of temperature gradient G and growth rate R on the morphology and size of solidification microstructure [122]...
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TL;DR: In this article, the authors compared Nd-YAG laser welding and traditional GTAW processes on Hastelloy X superalloy for comparison and found that traditional welding technology has better ultimate tensile strength and ductility.
Abstract: Cracks induced by metal fatigue and structural aging effect can’t be fixed by traditional Gas Tungsten Arc Welding (GTAW), consequently cause the increasing of defect ratio. Although some cracks might be acceptable and qualified to field service standard subject to the military regulation, however, in certain areas, e.g. brazing and coating areas, the results are not ideal especially the HAZ and residual stress. In this study, Nd-YAG Laser welding and traditional GTAW processes were performed on Hastelloy X superalloy for comparison. Post-welding residual stress distribution was measured by X-ray diffraction method. Macro- and microstructure were observed by metallurgical OM and SEM in comparison to the hardness testing. Tensile test results show that traditional welding technology has better ultimate tensile strength and ductility. For the Nd:YAG laser welding, residual stress is limited to 3mm of the both sides of weld and drops drastically, while higher amplitude and widely spread in the GTAW welding. It is proposed that combining both methods, the repairing process can be optimized to reduce the defect ratio and save repairing time.
7 citations
Cites background from "Welding Metallurgy of"
...It is well known that welding residual stresses are detrimental to the integrity and fitness for service of welded industrial structures due to their susceptibility to fracture criterion, fatigue, hydrogen-induced cracking and stress-corrosion cracking [7]....
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01 Jan 2008
TL;DR: In this article, the authors focused on the thermo and fluid dynamical phenomena occuring during a autogenous or non-autogenous arc fusion and its effect on the workpiece.
Abstract: This investigation is devoted to the study of welding and its effect on the workpiece, focusing on the thermo and fluid dynamical phenomena occuring during a autogenous or nonautogenous arc fusion ...
7 citations
Cites methods from "Welding Metallurgy of"
...It can also model heat losses from the workpiece, which is usually the type of transfer efficiency that is physically measured, using for example a calorimeter (see [50])....
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References
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TL;DR: In this article, the state of the art in selective laser sintering/melting (SLS/SLM) processing of aluminium powders is reviewed from different perspectives, including powder metallurgy (P/M), pulsed electric current (PECS), and laser welding of aluminium alloys.
1,172 citations
TL;DR: In this article, the authors show that the pre-existing dislocation network, which maintains its configuration during the entire plastic deformation, is an ideal modulator that is able to slow down but not entirely block the dislocation motion.
557 citations
TL;DR: In this article, the fundamental understanding of structure-properties relationship in automotive steels resistance spot welds is discussed. And a brief review of friction stir spot welding, as an alternative to RSW, is also included.
Abstract: Spot welding, particularly resistance spot welding (RSW), is a critical joining process in automotive industry. The development of advanced high strength steels for applications in automotive industry is accompanied with a challenge to better understand the physical and mechanical metallurgy of these materials during RSW. The present paper critically reviews the fundamental understanding of structure–properties relationship in automotive steels resistance spot welds. The focus is on the metallurgical characteristics, hardness–microstructure correlation, interfacial to pullout failure mode transition and mechanical performance of steel resistance spot welds under quasi-static, fatigue and impact loading conditions. A brief review of friction stir spot welding, as an alternative to RSW, is also included.
369 citations
TL;DR: In this article, a unified equation to compute the energy density is proposed to compare works performed with distinct equipment and experimental conditions, covering the major process parameters: power, travel speed, heat source dimension, hatch distance, deposited layer thickness and material grain size.
369 citations
TL;DR: This study attempted to predict solidification defects by DNN regression with a small dataset that contains 487 data points and found that a pre-trained and fine-tuned DNN shows better generalization performance over shallow neural network, support vector machine, and DNN trained by conventional methods.
314 citations