scholarly journals Laser pressure welding of Al-Li alloy 2198: effect of welding parameters on fusion zone characteristics associated with mechanical properties

2020 ◽  
Vol 39 (1) ◽  
pp. 146-156 ◽  
Author(s):  
Tianbo Zhao ◽  
Yutaka S. Sato ◽  
Rongshi Xiao ◽  
Ting Huang ◽  
Jingquan Zhang
Keyword(s):  
Fusion Zone ◽  
Peak Load ◽  
Shear Behavior ◽  
External Pressure ◽  
Fusion Welding ◽  
Welding Parameters ◽  
Tensile Shear ◽  
Pressure Welding ◽  
Equiaxed Zone ◽  
Welding Defect

AbstractAl-Li alloy 2198 exhibits good combination of toughness and strength but its application is strongly limited by the poor weldability due to the formation of porosities during fusion-welding. This is the first study proposing and verifying a new approach to produce defect-free laser welds of poorly fusion-weldable Al-Li alloy 2198 with applied external pressure, i.e., feasibility of laser pressure welding to Al-Li alloy 2198 was examined. The microstructures associated with tensile shear behavior of laser pressure welded Al-Li alloy 2198 obtained at various welding parameters were analyzed. The results showed that formation of the welding defect in the weld could be successfully suppressed by applying laser pressure welding, even without shielding gas. Three microstructural zones, including the chill zone, the columnar zone and the equiaxed zone were observed in the fusion zone. Size of fusion zone and area fraction of porosities generally increased with increasing roller pressure and welding heat-input, and they dominantly affected the tensile shear behavior, including the peak load and the failure mode, of the weld.

scholarly journals Microstructure Evolution and Failure Modes of a Resistance Spot Welded TWIP Steel

2018 ◽  
Vol 23 (4) ◽  
pp. 460-473
Author(s):  
Tiago Colombo ◽  
Guilherme dos Santos ◽  
Pedro Teruel ◽  
Jorge Otubo ◽  
Alfredo Faria
Keyword(s):  
Failure Mode ◽  
Fusion Zone ◽  
Heat Affected Zone ◽  
Failure Modes ◽  
Twip Steel ◽  
Welding Parameters ◽  
Scanning Electron Micrographs ◽  
Tensile Shear ◽  
Shear Tests ◽  
Resistance Spot

Abstract This study discusses the microstructure, quasi-static mechanical strength and failure modes of TWIP steel weld spots. Weld spots were produced by varying the main resistance spot welding parameters: welding current, welding time and electrode compression force. All the samples showed a remarkable material hardness mismatch between the fusion zone, the heat affected zone and the base material, as evidenced by microindentation maps. Hardness at the fusion zone is lower than that of heat-affected zone and base metal, which facilitates interfacial failure mode during tensile-shear tests. However, high heat inputs promoted the failure mode changes to partial interfacial mode and then to pullout mode during tensile-shear tests as confirmed by Scanning Electron Micrographs. These changes in failure mode were accompanied by a notable increase in tensile-shear strength and energy absorption capability.

Investigation of Microstructure and Mechanical Properties of Resistance Spot Welded Dissimilar Joints Between Ferritic Stainless Steel and Weathering Steel

2015 ◽  
Vol 766-767 ◽  
pp. 770-779 ◽  
Author(s):  
A Subrammanian ◽  
D.B. Jabaraj ◽  
V.K. Bupesh Raja
Keyword(s):  
Stainless Steel ◽  
Fusion Zone ◽  
Ferritic Stainless Steel ◽  
Spot Welding ◽  
Peak Load ◽  
Weathering Steel ◽  
Tensile Shear ◽  
Dissimilar Joints ◽  
Resistance Spot ◽  
Mode Of Failure

Resistance spot welding is widely used in automobile and rail car manufacturing industries. In this research work, resistance spot welded dissimilar joints of ferritic stainless steel and weathering steel sheets is investigated for mechanical and metallurgical properties. Ferritic stainless steel AISI 409M and weathering steel corten A (ASTM A 242) of 2mm thickness were used in this work. Spot welding was done at different current values, keeping other parameters such as electrode force, electrode tip diameter and weld time as constant. Test specimens were subjected to tensile shear test and micro hardness test to assess the mechanical properties of the weld joints. The influence of welding current on nugget growth, fusion zone hardness, peak load, and failure energy and failure mode during tensile shear test, was investigated at various current ratings. The results showed that, with increasing value of current, peak load increased correspondingly. Nugget shape was found to be near symmetrical. Nugget diameter was found to be increasing with increase in current, in expulsion free welds. Interfacial mode of failure was noticed at low current values, whereas, at higher current values, pull out mode of failure was observed. Presence of martensite was observed in the fusion zone. Micro hardness values at fusion zone were found to be more than that of both heat affected zones and base metals.

Solid Freeform Fabrication of Al-Li 2199 via Controlled-Short-Circuit-MIG Welding

2011 ◽  
Vol 409 ◽  
pp. 843-848
Author(s):  
David W. Heard ◽  
Julien Boselli ◽  
Raynald Gauvin ◽  
Mathieu Brochu
Keyword(s):  
Photoelectron Spectroscopy ◽  
Solid Freeform Fabrication ◽  
Short Circuit ◽  
Lithium Concentration ◽  
Gas Metal Arc Welding ◽  
Fusion Welding ◽  
Welding Parameters ◽  
Freeform Fabrication ◽  
Metal Arc Welding ◽  
Welding Processes

Aluminum-lithium (Al-Li) alloys are of interest to the aerospace and aeronautical industries as rising fuel costs and increasing environmental restrictions are promoting reductions in vehicle weight. However, Al-Li alloys suffer from several issues during fusion welding processes including solute segregation and depletion. Solid freeform fabrication (SFF) of materials is a repair or rapid prototyping process, in which the deposited feedstock is built-up via a layering process to the required geometry. Recent developments have led to the investigation of SFF processes via Gas Metal Arc Welding (GMAW) capable of producing functional metallic components. A SFF process via GMAW would be instrumental in reducing costs associated with the production and repair of Al-Li components. Furthermore the newly developed Controlled-Short-Circuit-MIG (CSC-MIG) process provides the ability to control the weld parameters with a high degree of accuracy, thus enabling the optimization of the solidification parameters required to avoid solute depletion and segregation within an Al-Li alloy. The objective of this study is to develop the welding parameters required to avoid lithium depletion and segregation. In the present study weldments were produced via CSC-MIG process, using Al-Li 2199 sheet samples as the filler material. The residual lithium concentration within the weldments was then determined via Atomic Absorption (AA) and X-ray Photoelectron Spectroscopy (XPS). The microstructure was analyzed using High Resolution Scanning Electron Microscopy (HR-SEM). Finally the mechanical properties of welded samples were determined through the application of hardness and tensile testing.

Effect of double-sided friction stir welding on the mechanical and microstructural characteristics of AA5754 aluminium alloy

2021 ◽  
Vol 63 (9) ◽  
pp. 829-835
Author(s):  
Sare Çelik ◽  
Fatmagül Tolun
Keyword(s):  
Friction Stir Welding ◽  
Al Alloys ◽  
Fusion Welding ◽  
Welding Parameters ◽  
Al Alloy ◽  
Test Results ◽  
Feeding Rates ◽  
Microstructural Characteristics ◽  
Friction Stir ◽  
Tool Tilt Angle

Abstract AA5754Al alloy is widely used in industry. However, as in the case of all Al alloys, the 5xxx series Al alloys cannot be easily joined through fusion welding techniques. To address this problem, in this study, the effect of double-sided friction stir welding at various tool rotational speeds (450, 710, and 900 rpm), feeding rates (40, 50, and 80 mm × min-1), and tool tilt angles (0°, 1°, 2°) on the welding parameters and mechanical and microstructural characteristics of AA5754 Al alloy was determined. Tensile strength tests and microhardness tests were performed to examine the mechanical properties of the welded specimens. The microstructures of the welded zone were examined by obtaining optical microscopy and scanning electron microscopy images. The tensile test results indicated that the specimens exhibited the highest welding performance of 95.17 % at a tool rotational speed, feed rate, and tool tilt angle of 450 rpm, 50 mm × min-1 and 1°, respectively.

scholarly journals Effect of Microstructure and Texture on Mechanical Properties of Resistance Spot Welded High Strength Steel 22MnB5 and 5A06 Aluminium Alloy

Metals ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 685
Author(s):  
Xiaoqing Jiang ◽  
Shujun Chen ◽  
Jinlong Gong ◽  
Zhenyang Lu
Keyword(s):  
Mechanical Properties ◽  
Shear Strength ◽  
Aluminium Alloy ◽  
High Strength Steel ◽  
High Strength ◽  
Welding Parameters ◽  
Tensile Shear Strength ◽  
Tensile Shear ◽  
Resistance Spot ◽  
Effect Of Microstructure

The present study aims to investigate the effect of microstructure and texture on mechanical properties of resistance spot welding of high strength steel 22MnB5 and 5A06 aluminium alloy as a function of welding parameters. The pseudo-nugget zones (NZs) at the steel side have undergone full recrystallisation with a fine-grained ferrite structure containing a small amount of retained austenite and a high hardness of approximately 500 HV, which is a 35% increase in hardness compared to the base material (BM) with fine lath martensitic structure. The NZs at the Al side contain both a recrystallisation texture and shear texture. Higher tensile shear strength with increasing weld time could be linked to the random texture at the Al side. The highest tensile shear strength was achieved at an intermetallic layer thickness of 4 mm.

scholarly journals Microstructure and Fracture Behavior of Refill Friction Stir Spot Welded Joints of AA2024 Using a Novel Refill Technique

Metals ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 286 ◽  
Author(s):  
Lipeng Deng ◽  
Shuhan Li ◽  
Liming Ke ◽  
Jinhe Liu ◽  
Jidong Kang
Keyword(s):  
Spot Welding ◽  
Fracture Behavior ◽  
Shear Fracture ◽  
Load Capacity ◽  
Maximum Load ◽  
Fusion Welding ◽  
Tensile Shear ◽  
Friction Stir ◽  
Corona Ring ◽  
Spot Welded

Keyhole at the end of a conventional friction stir welded (FSW) joint is one of the major concerns in certain applications. To address this issue, a novel keyhole refilling technique was developed for conventional friction stir spot welding (FSSW) using resistance spot welding (RSW). A three-phase secondary rectifier resistance welder was adapted for the refill of the keyhole in the 1.5 mm + 1.5 mm friction stir spot welded 2024-T4 aluminum alloy joint. The microstructure and tensile shear fracture behavior were compared for both the unfilled and refilled specimens. The results show that the plug and keyhole are dominated by solid state welding with some localized zones by fusion welding. The refill process significantly improved the maximum load capacity in tensile shear testing as the corona ring is enlarged leading to a larger bonding area. Moreover, the tensile shear fracture occurs in the refilled FSSW specimens at the corona bonding zone, while the fracture occurs at the hook zone in the unfilled keyhole.

The Weldability of Primer-Coated Steel for Shipbuilding by CO2 Laser

2006 ◽  
Vol 321-323 ◽  
pp. 1745-1749 ◽  
Author(s):  
Jong Do Kim ◽  
Jin Seok Oh ◽  
Hyun Joon Park
Keyword(s):  
Welding Parameters ◽  
Coated Steel ◽  
Zinc Vapor ◽  
Welding Technology ◽  
Weld Material ◽  
Welding Defects ◽  
Lap Welding ◽  
Welding Defect ◽  
Alternative Idea

The application of laser welding technology has been considered to shipbuilding structure. However, when this technology is applied to primer-coated steel, good quality weld beads are not easily obtained. Because the primer-coated layer caused the spatter, humping bead and porosity which are main part of the welding defect attributed to the powerful vaporizing pressure of zinc. So we performed experiment with objectives of understanding spatter and porosity formation mechanism and producing sound weld beads in 6 t primer coated steels by a CO2 CW laser. The effects of welding parameters; defocused distance, welding speed, coated thickness and coated position; were investigated in the bead shape and penetration depth on bead and lap welding. Alternative idea was suggested to suspend the welding defect by giving a reasonable gap clearance for primer coated thickness. The zinc of primer has a boiling point that is lower than melting point of steel. Zinc vapor builds up at the interface between the two sheets and this tends to deteriorate the quality of the weld by ejecting weld material from lap position or leaving porosity. Significant effects of primer coated position were lap side rather than surface. Therefore introducing a small gap clearance in the lap position, the zinc vapor could escape through it and sound weld beads can be acquired. In conclusion, formation and suspension mechanism of the welding defects was suggested by controlling the factors.

Influence of Tool Rotational Speed on the Mechanical Properties of Friction Stir Welded Al-Cu-Li Alloy

2016 ◽  
Vol 857 ◽  
pp. 228-231
Author(s):  
Ho Sung Lee ◽  
Ye Rim Lee ◽  
Kyung Ju Min
Keyword(s):  
Mechanical Properties ◽  
Friction Stir Welding ◽  
Space Shuttle ◽  
Welding Process ◽  
High Strength ◽  
Fusion Welding ◽  
Welding Parameters ◽  
Friction Stir ◽  
Mechanical And Microstructural Properties ◽  
Tool Rotation

Aluminum-Lithium alloys have been found to exhibit superior mechanical properties as compared to the conventional aerospace aluminum alloys in terms of high strength, high modulus, low density, good corrosion resistance and fracture toughness at cryogenic temperatures. Even though they do not form low-melting eutectics during fusion welding, there are still problems like porosity, solidification cracking, and loss of lithium. This is why solid state friction stir welding is important in this alloy. It is known that using Al-Cu-Li alloy and friction stir welding to super lightweight external tank for space shuttle, significant weight reduction has been achieved. The objective of this paper is to investigate the effect of friction stir tool rotation speed on mechanical and microstructural properties of Al-Cu-Li alloy. The plates were joined with friction stir welding process using different tool rotation speeds (300-800 rpm) and welding speeds (120-420 mm/min), which are the two prime welding parameters in this process.

Research on Plasma Arc Melting-Pressure Welding Method for Nitinol Alloy Wire

2013 ◽  
Vol 631-632 ◽  
pp. 530-533
Author(s):  
Yue Lan Xu ◽  
Xiao Yong Hu ◽  
Jun Zhang
Keyword(s):  
Base Metal ◽  
Welding Process ◽  
Fusion Welding ◽  
Plasma Arc ◽  
Pressure Welding ◽  
Alloy Wire ◽  
Melting Pressure ◽  
Arc Melting ◽  
Nitinol Alloy ◽  
Fusion Weld

According to the problem of the joint performance degradation in melting nitinol alloy wire connection, the method of melting-pressure connection applying plasma arc welding as melting heat source was designed and the special flexible fixture was invented to realize the welding process. the Φ2mm nitinol alloy wire connected by this method is shaped well . The characteristic of the welded joint microcosmic formation shows that the grains appear rheological pattern in heat-affected zone. The tensile strength of the joint by plasma arc melting-pressure welding after annealing is 89% of the base metal, it also increases by 43% comparing with the plasma fusion welding joint. The shape memory of the joint is about 97.1% of the base metal, which is higher than the fusion weld joints by 3.3% .

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