Showing papers on "Weldability published in 2017"
TL;DR: A review on the physical metallurgy, processing strategies, strengthening mechanisms and mechanical properties of Fe-Mn-Al-C steels from the published literature over a period of many years, and suggests avenues for future applications of these alloys in the automotive sector as mentioned in this paper.
368 citations
TL;DR: In this article, a detailed review of welding and joining processes applied to NiTi, in similar and dissimilar combinations considering both fusion and solid-state processes, is presented, and a special section is devoted to this technique.
211 citations
TL;DR: In this paper, a review article has been made to critically analyse the issues and challenges associated with the weldability of high strength pipeline materials, including welding corrosion, hydrogen embrittlement, residual stress, weld repairing and deteriorated heat affected zone.
138 citations
TL;DR: In this article, a review on the resistance spot welding (RSW) of Al/Al alloys, Al alloys/steel, Al/Mg alloys and Al/Ti alloys with focus on structure, properties, and performance relationships is presented.
Abstract: This paper presents a review on the resistance spot welding (RSW) of Al/Al alloys, Al alloys/steel, Al/Mg alloys, and Al/Ti alloys, with focus on structure, properties, and performance relationships. It also includes weld bonding, effect of welding parameters on joint quality, main metallurgical defects in Al spot welds, and electrode degradation. The high contact resistance, induced by the presence of oxide layer on the surface of Al alloys, and the need for application of high welding current during RSW of Al alloys result in rapid electrode tip wear and inconsistency in weld quality. Studies have shown that cleaning the oxide layer, sliding of a few microns between sheets, enhancing the electrode force, and the application of a low-current pre-heating can significantly reduce the contact resistance and improve joint quality. For Al/steel dissimilar RSW, the technique of resistance element welding, the use of optimized electrode morphology, the technique of RSW with cover plates, and the use of interlayers such as Al-Mg, AlSi12, and AlCu28 alloys were found to suppress the formation of brittle intermetallic compounds (IMC) and improve the joint quality. The employment of pure Ni foil, Au-coated Ni foil, Sn-coated steel, and Zn-coated steel interlayers was also found to restrict the formation of brittle IMCs during RSW of Al/Mg alloys. Furthermore, the techniques of RSW with cover plates and RSW under the influence of electromagnetic stirring effect were found to improve the weldability of Al/Ti dissimilar alloys.
123 citations
TL;DR: In this paper, the formation mechanisms and control methods of acicular ferrite in HSLA steels were studied, and the effect of austenitizing conditions, continuous cooling rate, and isothermal quenching time and temperature was reviewed.
99 citations
TL;DR: In this article, a review of metallurgical, mechanical, and corrosion properties of commercial marine alloy duplex stainless steel AISI 2205 with special reference to its weldability, machinability, and surfacing is presented.
94 citations
TL;DR: In this article, the authors present the specific microstructural features and mechanical properties, in particular tensile strength, of such welds, focusing on the material flow and welding defects, on the intermetallic compounds, on constitutional liquation, on particularities related to dissimilar lap welding and finally on process modifications to improve dissimilar friction stir weldability.
Abstract: Friction stir welding is a rather recent welding process (patented in 1991 by Thomas et al., ‘Improvements to friction welding’ UK patent application no. 9125978.8, US Patent 5460317, 1995) that has shown great potential for welding dissimilar materials even of different metallic nature, e.g. Al to steel, Mg to steel, Al to Ti, Mg to Ti, Al to Cu, Al to Mg. This review presents the specific microstructural features and mechanical properties, in particular tensile strength, of such welds. A focus will be on the material flow and welding defects, on the intermetallic compounds, on constitutional liquation, on particularities related to dissimilar lap welding and finally on process modifications to improve dissimilar friction stir weldability.
81 citations
TL;DR: In this article, a series of advanced oxidation-resistant FeCrAl alloys with aluminum, niobium, and titanium carbide additions were investigated and compared before and after controlled laser-beam welding.
73 citations
TL;DR: In this article, the feasibility of using a fiber laser to perform a dissimilar metal joining was explored, and the laser offset welding (LOW) method was demonstrated to be a promising technique to join dissimilar metals welds, being capable to produce an effective bonding with good tensile strength.
70 citations
TL;DR: In this article, the microstructure and performance relationship in resistance spot welding of a martensitic advanced high strength steel was investigated and significant softening was observed in the heat affected zone (HAZ) due to allotriomorphic ferrite formation in the inter-critical HAZ and tempering of martensite in sub-critical HZ, with the latter plays more important role in mechanical properties of the spot welds.
Abstract: The paper addresses the process–microstructure–performance relationships in resistance spot welding of a martensitic advanced high strength steel. Significant softening was observed in the heat affected zone (HAZ) due to allotriomorphic ferrite formation in the inter-critical HAZ and tempering of martensite in sub-critical HAZ (SCHAZ), with the latter plays more important role in mechanical properties of the spot welds. The strain concentration associated with the HAZ softening promotes initiation of pullout failure from the soft SCHAZ. While, the peak load in the interfacial failure mode is governed by the fusion zone size, that of the pullout mode is significantly affected by the HAZ softening. To improve weldability of martensitic steels, the HAZ softening should be minimised via modifications in welding process or steel chemistry.
56 citations
TL;DR: In this paper, the weldability of super duplex stainless steel UNS S32750 (SDSS) was explored using a pulsed Nd: YAG laser welding machine with an average power of 600 W.
TL;DR: In this paper, a series of alloy compositions were designed to exploit precipitation of the G phase in a ferritic matrix at temperatures of 450-600°C in order to obtain yield strengths in excess of 2 GPa.
TL;DR: In this paper, the authors explored the feasibility of magnetic pulse welding of AA 1060 to Q235 steel sheet under a discharge voltage above 9.5 kV, and the weldability window of AA1060-Q235 steel sheets was established.
Abstract: The joining of dissimilar metals is required for lightweight structures. The efficient and mechanically robust uniform pressure electromagnetic actuator (UPEA) was used to magnetic pulse welding (MPW) dissimilar metal sheets in this study. This study explored the feasibility of MPW of AA 1060 to Q235 steel sheet. The effects of discharge voltage, vertical gaps between two sheets, and the effect of the width of the joining zone on the connection quality were investigated. The metallurgical joints were obtained under a discharge voltage above 9.5 kV, and the weldability window of AA1060 to Q235 steel sheets was established. Microstructure observations of the MPW joint revealed that the interface of the joint is close to flat. EDS mapping showed mutual diffusion of basic elements across the interface.
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TL;DR: Haynes 282 Alloy (Ni-19Cr-10Co-8.5Mo-1.5Al-2.1Ti) as mentioned in this paper has been shown to have high strength potential of age hardenable, γ′-strengthened alloys.
Abstract: While solid solution–strengthened alloys have inherent advantages for manufacturability, they do not have the high strength potential of age hardenable, γ′-strengthened alloys. One of these γ′ alloys, HAYNES 282 Alloy (Ni-19Cr-10Co-8.5Mo-1.5Al-2.1Ti), offers weldability and fabricability that is unmatched in wrought γ′ alloys of similar creep strength (eg, Waspaloy and Rene-41). With nearly twice the rupture strength at 700°C (1292°F) of the closest solid solution nickel alloys (like 617B), HAYNES 282 alloy offers both potential cost savings and improved manufacturability. Further, 282 alloy's excellent resistance to strain-age cracking during welding and good thermal stability offer a capacity for repairability that has proven to be the weak link in previous A-USC efforts. For these reasons, 282 alloy has been readily adopted by major gas turbine manufacturers and has become a leading candidate for emerging technology applications, like advanced ultra-supercritical steam, supercritical CO2, and others. HAYNES and 282 are registered trademarks of Haynes International, Inc.
TL;DR: In this article, a double-sided synchronous autogenous gas tungsten arc (GTA) welding (DSSAGW) was applied to high nitrogen austenitic stainless steel (HNASS).
TL;DR: In this paper, a model of emissivity changes was elaborated and successfully applied for temperature measurement in terms of varying emissivities during a welding thermal cycle, which is a valuable tool for welding process monitoring and control.
Abstract: Thermomechanically processed steels are materials of great mechanical properties connected with more than good weldability. This mixture makes them interesting for different types of industrial applications. When creating welded joints, a specified amount of heat is introduced into the welding area and a so called heat-affected zone (HAZ) is formed. The key issue is to reduce the width of the HAZ, because properties of the material in the HAZ are worse than in the base material. In the paper, thermographic measurements of HAZ temperatures were presented as a potential tool for quality assuring the welding process in terms of monitoring and control. The main issue solved was the precise temperature measurement in terms of varying emissivity during a welding thermal cycle. A model of emissivity changes was elaborated and successfully applied. Additionally, material in the HAZ was tested to reveal its properties and connect changes of those properties with heating parameters. The obtained results prove that correctly modeled emissivity allows measurement of temperature, which is a valuable tool for welding process monitoring.
TL;DR: In this article, the authors examined the local hydrogen concentration, trapping and distribution by two modern and advanced techniques: thermal desorption spectrometry (TDS) and support it by time of flight-secondary ion mass spectrometer (ToF-SIMS).
24 Mar 2017-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this paper, the microstructure-property relationship in high strength and high toughness 60mm thick ultra-heavy gauge plate steels characterized by ferrite-bainite multi-phase micro-structure was elucidated.
Abstract: We elucidate here the microstructure-property relationship in high strength and high toughness 60 mm thick ultra-heavy gauge plate steels characterized by ferrite-bainite multi-phase microstructure and compare with the conventional bainitic microstructure. Pilot-scale results indicated that high yield strength of ~486–508 MPa with high ductility of ~10% in uniform elongation, low yield to tensile (Y/T) ratio of ~0.74–0.77, excellent low temperature toughness of ~186–228 J at −60 °C and good weldability are obtained in a multi-phase steel through combination of controlled rolling and accelerated cooling. The multi-phase microstructure steel consisted of quasi-polygonal ferrite and lath bainite with the corresponding phase proportion of 3:2 and 2:3 at 1/4 thickness (1/4 t) and 1/2 thickness (1/2 t) locations, respectively. The positive impact of multi-phase microstructure on ductility, Y/T ratio, toughness and weldability were attributed to the following aspects: (a) results from Crussard-Jaoul (C-J) analysis indicated that the soft ferrite phase in the multi-phase microstructure favorably modifies the work hardening behavior and results in high ductility and low Y/T ratio; (b) multi-phase microstructure is beneficial in enhancing toughness by enhancing initiation energy for nucleation of crack; (c) multi-phase microstructure improves the toughness of heat affected zone by altering the size and distribution of martensite/austenite (M/A) constituent.
TL;DR: In this paper, an external non-rotational shoulder tool system derived from traditional tool in friction stir welding was used to join dissimilar Al and Mg alloys to increase cooling rate and reduce the amount of intermetallic compounds.
Abstract: In order to increase cooling rate and then reduce the amounts of intermetallic compounds, external non-rotational shoulder tool system derived from traditional tool in friction stir welding was used to join dissimilar Al and Mg alloys. In this study, based on the external non-rotational shoulder, the weldability of Al and Mg alloys was significantly improved. The non-rotational shoulder tool is propitious to make more materials into weld, increase cooling rate and then reduce material adhesion of rotational pin, obtaining sound joint with smaller flashes and smooth surface. Importantly, the thickness of intermetallic compounds layer is reduced compared with traditional tool. Meanwhile, hardness values of dissimilar joint present uneven distribution, resulting from complex intercalated structures in nugget zone (NZ) featured by intermetallic compound layers and fine recrystallized Mg and Al grains. Compared with traditional tool, non-rotational shoulder is beneficial to higher tensile properties of joint. Due to the intermetallic compound layer formed in the interface of Al-Mg, the welding joint easily fractures at the NZ, presenting the typical brittle fracture mode.
TL;DR: In this paper, the weldability of dissimilar T-joints between commercially pure titanium (cp-Ti) Grade 2 skin and Ti-6Al-4V Grade 5 stringer using a continuous wave 8kW ytterbium fiber laser as well as the possibility of subsequent laser straightening process of these joints were investigated.
Abstract: The weldability of dissimilar T-joints between commercially pure titanium (cp-Ti) Grade 2 skin and Ti-6Al-4V Grade 5 stringer using a continuous wave 8 kW ytterbium fiber laser as well as the possibility of subsequent laser straightening process of these joints were investigated. Based on the industrial standards ISO 4578:2011 and AWS D17.1:200, process development to compensate inherent angular distortion after welding by laser heating with the same equipment as for welding was carried out. The obtained results were effectively transferred to a 6-stringer-demonstrator with a length up to 500 mm. To investigate the shape and morphology of the welding seam as well as to verify its freedom from defects using the defined process parameters, metallographic transverse cross-sections and X-ray analyses were realized. In addition, the behavior of the welding seam geometry and the bending behavior of the specimens for varied process parameters were elucidated. For the welding process special attention to the shielding conditions and to the local and angular laser beam positioning was payed. To straighten the welded joints, laser straightening parameters inducing no microstructural changes were identified.
TL;DR: In this paper, weldability studies for laser welding of Zr52.5Ti5Al10Ni14.6Cu17.9 amorphous foils onto a Ti-6Al-4V (Ti 6-4) or Zr 702 substrate are conducted.
TL;DR: In this paper, the microstructure and corrosion properties of FSWed Mg alloys were investigated in two commercial families: wrought AZ31-H24 and die cast AM50.
TL;DR: In this paper, two approaches were used for laser beam welding of similar and dissimilar joints of AA7075 and AA5182 that aim to overcome the weldability problems of high-strength Al-Zn-Mg-Cu alloys.
TL;DR: In this paper, the optimal laser welding parameters of a dual-phase steel, more specifically the DP600, were determined by determining the optimal parameters to weld it with a pulsed laser.
TL;DR: In this article, the welding and weldability of Ni3Al, Fe3A, and TiAl alloys are discussed and their behavior when subjected to weld thermal cycles, and their weldability.
Abstract: Intermetallic alloys represent a unique class of materials with atomic arrangements that are different from those of conventional disordered alloys. Among them are alloys based on Ni3Al, Fe3Al, and TiAl. Intermetallic alloys have unique properties, such as high melting point, low density, high-temperature strength, and high-temperature corrosion and oxidation resistance. Their only disadvantage is the lack of ductility at room temperature and at elevated temperatures. However, they can be ductilised by micro- and macroalloying. Application of intermetallic alloys for structural use at elevated temperature depends on their ability to be welded using conventional welding procedures. This paper focuses on the development of these alloys, their behaviour when subjected to weld thermal cycles, and their weldability. Most intermetallic alloys are susceptible to cracking during or after welding, but some can be modified to have good weldability. The paper discusses welding and weldability of Ni3Al-, Fe3A...
TL;DR: In this article, the effect of laser focusing properties on weldability was investigated in high-power fiber laser welding of a 12-mm-thick high-strength steel plate.
Abstract: The effect of various high-power laser-welding parameters on obtaining deep penetration welds without weld defects has been investigated However, there are no studies on the effect of laser focusing In this study, high-power fiber laser welding of a 12-mm-thick high-strength steel plate was performed by using two optics systems with different power density distributions and focus depths (2 or 4 mm) to investigate the effects of laser focusing properties on weldability Full penetration welds without weld defects were obtained with the 4 mm focus depth optics system at low welding speeds of 25–50 mm/s High-speed video and X-ray transmission images showed that the behavior of the molten pool on the top surface during laser welding was more stable for the 4 mm system than for the 2 mm system The keyhole was stable with no large fluctuations, and no bubbles were formed in the keyhole This result was attributed to keeping the power density within 50–120 kW/mm2 to maintain a stable keyhole shape during the
TL;DR: In this paper, the authors investigated the effect of offset and microdilution effects on the weldability, microstructure and mechanical properties of a dissimilar butt welding of Nb-1Zr to the 321 stainless steel.
TL;DR: In this paper, a Mg/steel butt-welded plate was created by hybrid laser-tungsten inert gas double-sided welding with a Ni interlayer.
TL;DR: In this paper, the effect of C and N contents on the microstructure and precipitation in flat-rolled strips of V-microalloyed steels was investigated and the maximum precipitation strengthening from fine V(C,N) precipitates was obtained at an intermediate range of isothermal holding temperatures (600-650°C).
TL;DR: In this article, two different optics have been used in this project, oscillating-and triple-spot optics, and the results from the experiments show that both the oscillating optics and the triple spot optics can produce crack free welds The amount of pores is shown to be low for both cases.