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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Dissertation•
20 Jun 2019TL;DR: Inconel 738 LC (IN738LC) as mentioned in this paper is a superalliage with a haute temperature that is used extensively for recharging of turbomoteurs.
Abstract: Les superalliages a base de nickel durcis par precipitation γ' et notamment l'Inconel 738 LC (IN738LC), sont des materiaux largement utilises dans les parties chaudes de turbomoteurs d'avions et d'helicopteres. Ces materiaux disposent d'excellentes proprietes mecaniques a haute temperature. Toutefois, des defauts ou des fissures peuvent apparaitre sur ces pieces, lors de leur elaboration par fonderie ou bien pendant leur duree en service, ce qui necessite leur reparation. Cependant, les pieces constituees en IN738LC sont sujettes a de la fissuration au cours des procedes de reparation de type soudage. Il s'avere que le rechargement laser est une technique de fabrication additive prometteuse permettant de reparer des pieces abimees. Le present travail consiste en l'etude de la reparabilite par projection de poudre de l'alliage IN738LC repute non soudable. Cette etude comporte deux volets experimentaux et numeriques du rechargement de pieces en Inconel 738 LC au moyen du procede CLAD. Pour cela, nous avons realise des essais de rechargement suivant plusieurs configurations illustrant les cas de reparations rencontres industriellement. Deux mecanismes de fissuration distincts sont mis en evidence respectivement dans la zone affectee thermiquement du substrat et dans le depot. Une simulation multi-physique est egalement developpee pour rendre compte des phenomenes thermiques, mecaniques et metallurgiques observes lors du rechargement laser. Ces simulations sont comparees a des mesures experimentales pour validation. Enfin, ces outils de simulation sont utilises afin de definir des criteres numeriques de risque de fissuration. En resume, un prechauffage a haute temperature permet d'eliminer le risque de liquation et donc de fissures dans la ZAT ainsi que dans les depots, ce qui demontre qu'il est possible d'envisager une reparation sur cet alliage repute non soudable.
5 citations
Cites background from "Welding Metallurgy of"
...23 – Schéma représentatif des conditions menant à la fissuration au revenu : (a) diagramme de phase-type des superalliages à base de nickel ; (b) cycle thermique-type de soudage avec des traitements post-soudage ; (c) diagramme TTT de la précipitation de la phase γ′ ; (d) schéma en coupe d’une soudure ; (e) changements de microstructures dans la zone fondue et dans la ZAT [76]...
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...23 Schéma représentatif des conditions menant à la fissuration au revenu : (a) diagramme de phase-type des superalliages à base de nickel ; (b) cycle thermique-type de soudage avec des traitements post-soudage ; (c) diagramme TTT de la précipitation de la phase γ′ ; (d) schéma en coupe d’une soudure ; (e) changements de microstructures dans la zone fondue et dans la ZAT [76] ....
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Posted Content•
01 Jan 2014
TL;DR: In this paper, an elaborate study has been conducted to estimate the cooling rate of the Gas Tungsten arc (GTA) welded steel butt joints of grade AISI 1090.
Abstract: An elaborate study has been conducted in this article to estimate the cooling rate of the Gas Tungsten arc (GTA) welded steel butt joints of grade AISI 1090. The temperature dependent thermal parameters has been investigated in connection with developed rate of cooling. Experiment has been carried out ffto determine the thermal cycle formed along the longitudinal direction from weld bead. Implementing experimental temperatures, Adams empirical cooling rate correlation has incorporated to analyze rate of cooling. A correlation has been suggested in this study, derived from thick plate temperature distribution model. To find out the heat loss from the joint, Vinokurov’s empirical combined heat transfer coefficient has been utilized and with it has verified with conventional heat transfer coefficient based on convection and radiation. Cooling rate has been found out to be very rapid at z = 36mm to z = 108mm based on thick plate model and it has completely agreed with the variation of Adams correlation. At higher temperatures above 800oC, heat loss due to radiation completely dominates the convection and lower temperatures convection heat loss influences much than radiation. Heat loss due to convection and radiation fully justified with the results produced based on cooling rate and rapid cooling near the fusion boundary exists only for 5s-10s.
5 citations
Cites methods from "Welding Metallurgy of"
...To validate the cooling rate based on equation (2), empirical correlation of cooling rate denoted as Adams cooling rate for 2-dimensional heat flow has been considered and it can be written as [17]:...
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TL;DR: In this article, the role of interpass temperature and heat input on the hot hardness and wear behavior of welded structural steels was investigated and the influence of different microstructural parameters such as phase content, processing and the resulting temperature-hardness coherence on the wear resistance were evaluated within a high temperature abrasion test and a hot hardness test rig.
Abstract: In several industrial applications wear resistance of structural steels is required. Also enhanced temperature can occur when handling hot materials, e.g. in steel industry. Within this study a low alloyed structural steel (carbon steel S355) and a high temperature (HT) 9 % Cr steel ASTM A332 P92 were chosen for investigation. Repair welds with flux cored wires which are often required in applications were investigated, aiming on the role of interpass temperatures, the resulting effect of cooling conditions on the microstructure and their HT abrasion resistance. The influence of different microstructural parameters such as phase content, processing and the resulting temperature-hardness coherence on the wear resistance are evaluated within a high temperature abrasion test and a hot hardness test rig. Results indicate a strong influence of interpass temperature and heat input on the hot hardness and wear behaviour of welded structural steels.
5 citations
Cites background from "Welding Metallurgy of"
...The influence of welding parameters on the microstructure cannot be neglected [4,8,9]....
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TL;DR: In this paper, the effect of non-equilibrium solidification conditions on the eutectic and post-eutectical reactions temperature and percentage of the phases were investigated using computer-aided cooling curve thermal analysis.
Abstract: Effect of non-equilibrium solidification conditions on the eutectic and post-eutectic reactions temperature and percentage of the phases were investigated using computer-aided cooling curve thermal analysis. In addition, hardness, secondary dendrite arm spacing, and maximum pore size were studied at different cooling conditions. Cooling curves were determined by setting thermocouples in the center of the molds. Solid fractions were calculated by Newtonian baseline technique. Results showed that increasing the cooling rate shifted the temperature of post-eutectic reaction upward, except final reaction. Higher cooling rate increased eutectic percentage about 4 %, but reduced total percentage of post-eutectic phases. Additionally, increasing the cooling rate shortened the maximum porosity diameter and secondary dendrite arm spacing and increased the hardness of the alloy.
5 citations
TL;DR: In this paper, the authors compared the performance of RSW and FSSW on aluminum alloy (2024-T3) and found that RSW has a higher tensile shear force value compared to FSW, which is explained by the coarse dendritic structure in RSW compared to the plastically deformed stir zone and heat affected zone in FSW.
Abstract: This investigation is performed to compare the resistance spot welding (RSW) of aluminum alloy (2024-T3) with friction stir spot welding (FSSW) techniques. In this work, parameters of both resistance spot welding (RSW) and friction stir spot welding (FSSW) techniques were optimized and the optimum welding variables for both techniques were obtained. For FSSW, the tensile shear strength increased with increasing probe length, tool rotational speed and tool holding time. Tensile shear force value of RSW is about 66% of that of FSSW. This is explained by the coarse dendritic structure in resistance spot welding compared to the plastically deformed stir zone and heat affected zone in FSSW. The ratio of nugget shear strength of RSW and FSSW to base metal is about 71% and 149% respectively. The maximum hardness was obtained in stir zone at the surface of the tool. Very fine grain size of about 4 microns was obtained in stir zone followed by elongated and rotated grains in TMAZ where dynamic recrystallization did not occur.
5 citations
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.
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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.
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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.
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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