Showing papers on "Heat-affected zone published in 2014"
TL;DR: In this paper, the effects of materials position and welding speed on the material flow, microstructure, microhardness distribution and tensile property of the joints were investigated, and it was revealed that the material mixing is much more effective when AA6061 alloy was located on the advancing side and multiple vortexes centers formed vertically in the nugget.
287 citations
TL;DR: In this article, the welding nugget can be considered as aluminum matrix composite, which is enhanced by dispersed sheared-off steel fragments encompassed by a thin inter-metallic layer or simply intermetallic particles.
243 citations
TL;DR: In this article, it was demonstrated that the strength of the nugget could be increased by the use of a higher strength interlayer during friction stir welding, however, this strength recovery cannot be attainable in the heat affected zone.
Abstract: Although sound AA6061-T6 joints can be produced by friction stir welding, a loss in strength takes place in the weld region. In this study, it was demonstrated that the strength of the nugget could be increased by the use of a higher strength interlayer during friction stir welding. This strength recovery cannot, however, be attainable in the heat affected zone. Although an external cooling was applied during welding in order to increase strength in the heat affected zone, it was not sufficient for achieving the required cooling condition for improved strength.
132 citations
01 Jul 2014-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this paper, the microstructure and mechanical properties of plain carbon steel and AISI 430 ferritic stainless steel dissimilar welds are carried out, and it is found that weld heat input can strongly affect grain growth phenomenon along with the amount and composition of carbides and intergranular martensite.
Abstract: In this work, examinations on the microstructure and mechanical properties of plain carbon steel and AISI 430 ferritic stainless steel dissimilar welds are carried out. Welding is conducted in both autogenous and using ER309L austenitic filler rod conditions through gas tungsten arc welding process. The results indicate that fully-ferritic and duplex ferritic–martensitic microstructures are formed for autogenous and filler-added welds, respectively. Carbide precipitation and formation of martensite at ferrite grain boundaries (intergranular martensite) as well as grain growth occur in the heat affected zone (HAZ) of AISI 430 steel. It is found that weld heat input can strongly affect grain growth phenomenon along with the amount and the composition of carbides and intergranular martensite. Acquired mechanical characteristics of weld in the case of using filler metal are significantly higher than those of autogenous one. Accordingly, ultimate tensile strength (UTS), hardness, and absorbed energy during tensile test of weld metal are increased from 662 MPa to 910 MPa, 140 Hv to 385 Hv, and 53.6 J m −3 to 79 J m −3 , respectively by filler metal addition. From fracture surfaces, predominantly ductile fracture is observed in the specimen welded with filler metal while mainly cleavage fracture occurs in the autogenous weld metal.
130 citations
TL;DR: In this article, an optimization of ultrasonic spot welding parameters for joining 3003 Aluminum alloy with 304 Stainless steel was performed at various clamping pressures and energy levels for investigating its effect on microstructure, mechanical properties and bond quality of the weld.
121 citations
TL;DR: In this paper, the effect of the processing parameters on the weld bead geometry was examined, and the microstructure and mechanical properties of the optimal joint were investigated, showing that the focal position is a key parameter in high power fiber laser welding of thick plates.
116 citations
TL;DR: In this article, a numerical and experimental investigation of laser welding of titanium alloy (Ti6Al4V) for modeling the temperature distribution to predict the heat affected zone (HAZ), depth and width of the molten pool.
Abstract: This paper reports on a numerical and experimental investigation of laser welding of titanium alloy (Ti6Al4V) for modeling the temperature distribution to predict the heat affected zone (HAZ), depth and width of the molten pool. This is a transient three-dimensional problem in which, because of simplicity, the weld pool surface is considered flat. The complex physical phenomenon causing the formation of keyhole has not been considered. The temperature histories of welding process were studied. It was observed that the finite volume thermal model was in good agreement with the experimental data. Also, we predicted the temperature as a function of distance at different laser welding speeds and saw that at each welding speed, the temperature profile was decreased sharply in points close to the laser beam center, and then decreased slightly in the far region from the laser beam center. The model prediction error was found to be in the 2–17% range with most numerical values falling within 7% of the experimental values.
116 citations
TL;DR: In this article, the microstructure and mechanical properties of UNS S32750 super duplex stainless steel (SDSS)/API X-65 high strength low alloy steel (HSLA) dissimilar joint were investigated.
113 citations
23 Jun 2014-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this article, the microstructure, micro-hardness and room tensile mechanical properties of hybrid fabricated TC11 titanium alloy sample were examined, and it was shown that the hybrid manufactured sample consists of three typical zones: the laser additive manufactured zone (LAMZ), the wrought substrate zone (WSZ), and the bonding zone without any metallurgical defects.
Abstract: The hybrid fabricating technique by laser additive manufacturing provides an attractive potential for manufacturing titanium alloy components. Microstructure, micro-hardness and room tensile mechanical properties of hybrid fabricated TC11 titanium alloy sample were examined. Results show that the hybrid manufactured sample consists of three typical zones: the laser additive manufactured zone (LAMZ), the wrought substrate zone (WSZ), and the bonding zone without any metallurgical defects. Superfine basket-wave microstructure forms in LAMZ and heat affected zone (HAZ) due to the rapid cooling rate. No obvious grain growth or recrystallization occurs in the HAZ. A special bimodal microstructure consisting of coarse fork-like primary α and fine β transformed microstructure is found in the transition zone due to the heat effect in α+β region. The hybrid fabricated TC11 sample has good mechanical properties with tensile strength of 1033±13 MPa and elongation of 6.8±0.2%. The fracture of hybrid sample occurs in the substrate in tensile testing, meaning that the bonding zone has better mechanical properties than the substrate.
112 citations
TL;DR: In this paper, the authors applied FSpW to join the 6061-T4 aluminum alloy sheet with 2mm thickness and found that the tensile/shear strength reached the maximum of 7117.0 and 4555.4 N at the welding condition of the rotational speed of 1500rpm and duration time of 4 s.
110 citations
TL;DR: In this article, an underwater FSW (underwater FSW) was employed for fabricating the weld, and the weld obtained by underwater FFW was analyzed via comparing with the welding obtained under same parameters by classical FSW.
TL;DR: In this article, a three-dimensional turbulent steady state numerical model was used to investigate the influence of an alternating current (AC) magnetic field during high power laser beam keyhole welding of 20mm thick stainless steel AISI 304 being modeled as an ideal non-ferromagnetic material.
TL;DR: In this article, the authors investigated the welding deformation in low carbon steel thin-plate joints induced by laser beam welding and CO 2 gas arc welding by means of both numerical simulation technology and experimental method in the current study.
TL;DR: In this article, the ability to relate weld strength to the welding process data, namely dissipated power and displacement of the sonotrode, in ultrasonic welding of thermoplastic composite parts with flat energy directors, is described.
Abstract: Ultrasonic welding of thermoplastic composites is a very interesting joining technique as a result of good quality joints, very short welding times and the fact that no foreign material, e.g. a metal mesh, is required at the welding interface in any case. This paper describes one further advantage, the ability to relate weld strength to the welding process data, namely dissipated power and displacement of the sonotrode, in ultrasonic welding of thermoplastic composite parts with flat energy directors. This relationship, combined with displacement-controlled welding, allows for fast definition of optimum welding parameters which consistently result in high-strength welded joints.
TL;DR: In this article, the effect of welding current at constant welding time was considered on the weld properties such as weld nugget size, tensile-shear load bearing capacity of welded materials, failure modes, failure energy, ductility, and microstructure of weld nuggets as well.
TL;DR: In this article, the authors demonstrate that solid-state friction welding not only permits to successfully join materials produced by selective laser melting (SLM), but also helps to significantly improve their ductility.
TL;DR: In this paper, the formation mechanism of spatter and the corresponding relationships between the spatter formation and molten pool behavior were investigated by using the high-speed camera and the X-ray transmission imaging system during laser welding under different welding parameters.
TL;DR: In this article, five different tool designs have been employed to analyse the influence of rotation speed and traverse speed over the microstructural and tensile properties of dissimilar AA2024 and AA6061 aluminium plates of 5mm thickness.
TL;DR: In this article, the microstructural evolution in the heat-affected zone (HAZ) of 5mm thick friction stir welded (FSW 2024Al-T351 joints during long-term natural aging and its effect on mechanical properties were investigated by a combination of transmission electron microscopy, atom probe tomography, differential scanning calorimetry and mechanical property tests.
TL;DR: In this paper, a 304L austenitic stainless steel was subjected to different heat inputs by shielded metal arc welding process using a standard 308L electrode and microstructural developments were characterized by using optical microscopy and electron backscattered diffraction, while the residual stresses were measured by X-ray diffraction using the sin 2 ψ method.
TL;DR: In this article, an attempt has been made to weld the precipitation hardened Nickel based super alloy Inconel 718 and austenitic stainless steel AISI 316L using Continuous Current Gas Tungsten Arc Welding (CCGTAW) and Pulsed Current GasTungsten arc Welding process employing ER2553 and ERNiCu-7 fillers.
03 Jan 2014-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this article, a steel weld joint fabricated by activated TIG (A-TIG) welding process has been investigated at 923 K over a stress range of 80-150 MPa.
Abstract: Creep rupture behavior of 9Cr–1.8W–0.5Mo–VNb (ASME grade 92) ferritic steel weld joint fabricated by activated TIG (A-TIG) welding process have been investigated at 923 K over a stress range of 80–150 MPa. The weld joint was comprise of fusion zone, heat affected zone (HAZ) and base metal. The HAZ consisted of coarse prior-austenite grain (CGHAZ), fine prior-austenite grain (FGHAZ) and intercritical (ICHAZ) regions in an order away from the fusion zone to base metal. A hardness trough was observed at the outer edge of HAZ of the weld joint. TEM investigation revealed the presence of coarse M23C6 precipitates and recovery of martensite lath structure into subgrain in the ICHAZ of the weld joint, leading to the hardness trough. The weld joint exhibited lower creep rupture lives than the base metal at relatively lower stresses. Creep rupture failure location of the weld joint was found to shift with applied stress. At high stresses fracture occurred in the base metal, whereas failure location shifted to FGHAZ at lower stresses with significant decrease in rupture ductility. SEM investigation of the creep ruptured specimens revealed precipitation of Laves phase across the joint, more extensively in the FGHAZ. On creep exposure, the hardness trough was found to shift from the ICHAZ to FGHAZ. Extensive creep cavitation was observed in the FGHAZ and was accompanied with the Laves phase, leading to the premature type IV failure of the steel weld joint at the FGHAZ.
TL;DR: In this article, a three dimensional laser deep penetration welding model in which volume of fluid (VOF) method was combined with a ray tracing algorithm was used to simulate the dynamic coupling between keyhole and molten pool in laser full penetration welding.
TL;DR: In this paper, the microstructural properties, tensile properties and low-cycle fatigue properties of a dual-phase steel (DP780) were investigated following its joining by three methods: laser welding, tungsten inert gas (TIG) welding, and metal active gas (MAG) welding.
TL;DR: In this paper, nominal friction stir [butt] welding process parameters for joining 4.76mm-thick aluminum alloys 6061-T6 and 7075t6 were established.
Abstract: The objective of this work is to establish nominal friction stir [butt] welding process parameters for joining 4.76-mm-thick aluminum alloys 6061-T6 and 7075-T6 and to improve the joint quality via programmed tool offsets. In addition, dynamic tool–workpiece interface temperatures are measured during welding and used to explain the effects of alloy placement and weld tool offset from the joint. Weld tool offsets into the retreating side AA7075 increase the measured tensile strength of the dissimilar joint. The increased joint strength is facilitated by lower average weld temperatures with increasing amount of AA7075 stirred into the nugget.
TL;DR: In this article, the microstructure of the fusion zone and the heat affected zone is investigated in resistance spot welding of AISI 430 ferritic stainless steels and the phase transformations which occur during weld thermal cycle were analyzed in details, based on the physical metallurgy of welding of the ferritic steels.
TL;DR: In this article, a tool wear characterization was carried out by weight loss measurement, pin profile photographic technique and microscopic observations using three types of tools made of W-1.1%La2O3 and two different grades of WC-Co based materials.
TL;DR: In this paper, the microstructure and mechanical properties of welding heat affected zone (HAZ) of three typical X80 pipeline steels have been studied using the welding thermal simulation method on a Gleeble-3500 thermal simulator.
23 Jun 2014-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this article, the microstructure, micro-and nano-hardness, and tensile properties of dual-phase (DP) and high strength low alloy (HSLA) steels were characterized by fiber laser welding (FLW).
Abstract: Similar and dissimilar welds of dual-phase (DP) and high strength low alloy (HSLA) steels were made by fiber laser welding (FLW). The welds were characterized with respect to microstructure, micro- and nano-hardness, and tensile properties. The fusion zone (FZ) in the DP welds consisted of fully martensitic structure; whereas HSLA and dissimilar weld FZ microstructure were mixture of martensite and bainite. Analytical transmission electron microscopy (TEM) confirmed bainite structures containing bainitic ferrite laths with intralath and interlath cementite. Precipitation of single variant carbides inside the bainitic ferrite laths were confirmed by measuring the interplanar spacing. The cooling rate in the FZ, estimated using Rosenthal equation, and continuous-cooling-transformation diagrams corroborated the microstructure formed. Nanoindentation was used to verify the hardness of these individual microconstituents, since a much lower nano-hardness for bainite (4.11 GPa) was observed compared to martensite (6.57 GPa) phase. Tensile failure occurred in the tempered area of the heat affected zone (HAZ) in the DP steel welded, which was confirmed by typical cup-like dimple fracture; likewise failure in the HSLA base metal, which occurred in dissimilar and HSLA welds, indicated distinctive dimple and shear dimple ductile morphology.
TL;DR: In this article, an underwater friction stir welding is carried out in order to reduce heat input comparing with traditional friction-stir welding and further improve the joint performances by varying welding temperature history by comparing the thermal cycle curves and distribution of residual stress of the plate welded in different media.