scholarly journals A Partitioning Method for Friction Stir Welded Joint of AA2219 Based on Tensile Test

Metals ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 65
Author(s):  
Guanglong Cao ◽  
Mingfa Ren ◽  
Yahui Zhang ◽  
Weibin Peng ◽  
Tong Li
Keyword(s):  
Mechanical Properties ◽  
Tensile Test ◽  
Welded Joint ◽  
Classical Method ◽  
Plastic Property ◽  
Image Correlation ◽  
Strain Hardening Exponent ◽  
Friction Stir ◽  
Detection Technology ◽  
The Cost

The partition of aluminum alloy welded joint often depends on microscopic methods such as scanning electron microscopy before. This paper provides a novel partitioning method, which can obtain the material properties and partition results at the same time based on tensile test. The mechanical properties of every point on the whole welded joint are first obtained by the digital image correlation (DIC) method. Then, the mechanical property function of the weld joint along the weld center is established due to the changes of plastic property and strain hardening exponent at each point and the boundary between different areas is then determined. Metallographic detection technology and nano-mechanical testing techniques are employed to validate this partitioning scheme. The partition result of the strategy proposed in this paper is consistent with the partitioning result of the classical method. Compared to classical method, the proposed partitioning method is more practical and effective, as it can obtain mechanical properties and partition boundary through a single tensile test and reduce the cost of metallographic test.

scholarly journals Comprehensive Analysis of the Microstructure and Mechanical Properties of Friction-Stir-Welded Low-Carbon High-Strength Steels with Tensile Strengths Ranging from 590 MPa to 1.5 GPa

2021 ◽  
Vol 11 (12) ◽  
pp. 5728
Author(s):  
HyeonJeong You ◽  
Minjung Kang ◽  
Sung Yi ◽  
Soongkeun Hyun ◽  
Cheolhee Kim
Keyword(s):  
Mechanical Properties ◽  
Tensile Test ◽  
Joint Strength ◽  
Solid Phase ◽  
Welding Process ◽  
High Strength Steels ◽  
High Strength ◽  
Low Carbon ◽  
Friction Stir ◽  
Welding Processes

High-strength steels are being increasingly employed in the automotive industry, requiring efficient welding processes. This study analyzed the materials and mechanical properties of high-strength automotive steels with strengths ranging from 590 MPa to 1500 MPa, subjected to friction stir welding (FSW), which is a solid-phase welding process. The high-strength steels were hardened by a high fraction of martensite, and the welds were composed of a recrystallized zone (RZ), a partially recrystallized zone (PRZ), a tempered zone (TZ), and an unaffected base metal (BM). The RZ exhibited a higher hardness than the BM and was fully martensitic when the BM strength was 980 MPa or higher. When the BM strength was 780 MPa or higher, the PRZ and TZ softened owing to tempered martensitic formation and were the fracture locations in the tensile test, whereas BM fracture occurred in the tensile test of the 590 MPa steel weld. The joint strength, determined by the hardness and width of the softened zone, increased and then saturated with an increase in the BM strength. From the results, we can conclude that the thermal history and size of the PRZ and TZ should be controlled to enhance the joint strength of automotive steels.

scholarly journals Effect of PWHT on the Microstructure and Mechanical Properties of Friction Stir Welded DP780 Steel

Metals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1097
Author(s):  
Umer Masood Chaudry ◽  
Seung-Chang Han ◽  
Fathia Alkelae ◽  
Tea-Sung Jun
Keyword(s):  
Mechanical Properties ◽  
Annealing Temperature ◽  
Tensile Elongation ◽  
Image Correlation ◽  
Frictional Heat ◽  
Uniaxial Tensile ◽  
Uniaxial Tensile Test ◽  
Friction Stir ◽  
Microstructure And Mechanical Properties ◽  
Dp780 Steel

In the present study, the effect of post-weld heat treatment (PWHT) on the microstructure and mechanical properties of friction stir welded (FSW) DP780 steel sheets was investigated. FSW was carried out at a constant tool rotation speed of 400 rpm and different welding speeds (200 mm/min and 400 min/min). A defect free weld was witnessed for both of the welding conditions. The mutual effect of severe plastic deformation and frictional heat generation by pin rotation during the FSW process resulted in grain refinement due to dynamic recrystallization in the stir zone (SZ) and thermo-mechanically affected zone (TMAZ). Lower tensile elongation and higher yield and ultimate tensile strengths were recorded for welded-samples as compared to the base material (BM) DP780 steel. The joints were subsequently annealed at various temperatures at 450–650 °C for 1 h. At higher annealing temperature, the work hardening rate of joints gradually decreased and subsequently failed in the softened heat-affected zone (HAZ) during the uniaxial tensile test. Reduction in yield strength and tensile strength was found in all PWHT conditions, though improvement in elongation was achieved by annealing at 550 °C. The digital image correlation analysis showed that an inhomogeneous strain distribution occurred in the FSWed samples, and the strain was particularly highly localized in the advancing side of interface zone. The nanoindentation measurements covering the FSWed joint were consistent with an increase of the annealing temperature. The various grains size in the BM, TMAZ, and SZ is the main factor monitoring the hardness distribution in these zones and the observed discrepancies in mechanical properties.

Microstructure and mechanical properties of friction stir welded joint of TRIP steel

2020 ◽  
Vol 56 ◽  
pp. 623-634 ◽  
Author(s):  
Wen Wang ◽  
Shengyi Zhang ◽  
Ke Qiao ◽  
Kuaishe Wang ◽  
Pai Peng ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Trip Steel ◽  
Welded Joint ◽  
Friction Stir ◽  
Microstructure And Mechanical Properties

scholarly journals A Numerical Strategy to Identify the FSW Process Optimal Parameters of a Butt-Welded Joint of Quasi-Pure Copper Plates: Modelling and Experimental Validation

2021 ◽  
Author(s):  
Monica Daniela IORDACHE ◽  
Claudiu BADULESCU ◽  
Malick DIAKHATE ◽  
Adrian CONSTANTIN ◽  
Eduard Laurentiu NITU ◽  
...  
Keyword(s):  
Welded Joint ◽  
Pure Copper ◽  
Correlation Method ◽  
Image Correlation ◽  
Experimental Investigations ◽  
Optimal Parameters ◽  
Friction Stir ◽  
Mass Scaling ◽  
Surface Response ◽  
Fsw Parameters

Abstract Determining the optimal parameters of the Friction Stir Welding (FSW) process, which are suitable for a given joint configuration, remains a great challenge and is often achieved through extremely time-consuming and costly experimental investigations. The present paper aims to propose a strategy for the identification of the optimal parameters for a butt-welded joint of 3-mm thick quasi-pure copper plates. This strategy is based on FEM (finite elements method) simulations and the optimal temperature that is supposedly known. A robust and efficient finite element model that is based on the Coupled Eulerian-Lagrangian (CEL) approach has been adopted and a temperature-dependent friction coefficient has been used. Besides, the mass scaling technique has been used to significantly reduce the simulation time. The thermo-mechanical behavior of the butt-welded joint was modeled using a Johnson-Cook plasticity model that was identified through lab tests at different temperatures. The results of the parametric study help to define the numerical surface response, and based on this latter one can found the optimal parameters, advancing (υa) and rotational (υr) speeds, of the FSW process. This numerical surface response has been validated with good agreement between the numerical prediction of the model and the experimental results. Furthermore, experimental investigations involving x-ray radiography, digital image correlation method, and fracture surface analysis have helped a better understanding of the effects of FSW parameters on the welded joint quality.

Simulation of the Global Response of Welded Joint Using Digital Image Correlation Measurement

2013 ◽  
Vol 749 ◽  
pp. 597-600
Author(s):  
Chao He ◽  
Shi Ming Cui ◽  
Yan Zeng Wu ◽  
Ze Fu Luo ◽  
Qing Yuan Wang
Keyword(s):  
Digital Image Correlation ◽  
Tensile Test ◽  
Tensile Properties ◽  
Digital Image ◽  
Welded Joint ◽  
Pure Aluminum ◽  
Local Stress ◽  
Image Correlation ◽  
Global Response ◽  
Mechanical Heterogeneity

The effect of the mechanical heterogeneity on the global and local tensile properties of laser-arc hybrid welded joints in industrial pure aluminum has been investigated. Digital image correlation method has been used during tensile test for mapping the strain distribution and to determine the local stress-strain curves of FZ and HAZ. The tensile properties of the various regions are very heterogeneous and HAZ is the weakest region because of the strain localizes during tensile test. Finite element technique was used to model the global response of welded joint based on local constitutive properties which could be determined from DIC results.

Local Elasto-Plastic Identification of the Behaviour of Friction Stir Welds with the Virtual Fields Method

2011 ◽  
Vol 70 ◽  
pp. 135-140 ◽  
Author(s):  
G. Le Louëdec ◽  
M.A. Sutton ◽  
Fabrice Pierron
Keyword(s):  
Mechanical Properties ◽  
Digital Image Correlation ◽  
Digital Image ◽  
High Speed ◽  
Weld Zone ◽  
Spatial Variations ◽  
Image Correlation ◽  
Virtual Fields Method ◽  
Full Field ◽  
Friction Stir

Welding is one of the most popular joining technologies in industry. Depending on the materials to be joined, the geometry of the parts and the number of parts to be joined, there is a wide variety of methods that can be used. These joining techniques share a common feature: the material in the weld zone experiences different thermo-mechanical history, resulting in significant variations in material microstructure and spatial heterogeneity in mechanical properties. To optimize the joining process, or to refine the design of welded structures, it is necessary to identify the local mechanical properties within the different regions of the weld. The development of full-field kinematic measurements (digital image correlation, speckle interferometry, etc.) helps to shed a new light on this problem. The large amount of experimental information attained with these methods makes it possible to visualize the spatial distribution of strain on the specimen surface. Full-field kinematic measurements provide more information regarding the spatial variations in material behaviour. As a consequence, it is now possible to quantify the spatial variations in mechanical properties within the weld region through a properly constructed inverse analysis procedure. High speed tensile tests have been performed on FSW aluminium welds. The test was performed on an MTS machine at a cross-head speed of up to 76 mm/s. Displacement fields were measured across the specimen by coupling digital image correlation with a high-speed camera (Phantom V7.1) taking 1000 frames per second. Then, through the use of the virtual fields method it is possible to retrieve the mechanical parameters of the different areas of the weld from the strain field and the loading. The elastic parameters (Young’s modulus and Poisson’s ratio) are supposed to be constant through the weld. Their identification was carried out using the virtual fields method in elasticity using the data of the early stage of the experiment. Assuming that the mechanical properties (elastic and plastic) of the weld are constant through the thickness, the plastic parameters were identified on small sections through the specimen, using a simple linear hardening model. This method leads to a discrete identification of the evolution of the mechanical properties through the weld. It allows the understanding of the slight variations of yield stress and hardening due to the complexity of the welding process.

Study on the Microstructure and Mechanical Properties of Welding Joints of 7A05 Aluminum Alloy by FSW

2014 ◽  
Vol 496-500 ◽  
pp. 110-113
Author(s):  
Dong Gao Chen ◽  
Jin He Liu ◽  
Zhi Hua Ma ◽  
Wu Lin Yang
Keyword(s):  
Mechanical Properties ◽  
Aluminum Alloy ◽  
Friction Stir Welding ◽  
Welding Speed ◽  
Welded Joint ◽  
Optical Microscope ◽  
Nugget Zone ◽  
Friction Stir ◽  
Microstructure And Mechanical Properties ◽  
Welding Joints

The7A05 aluminum alloy of the 10mm thickness was welded by the friction stir welding. The microstructure and mechanical Properties of the welded joint was researched by the optical microscope, etc. The results showed: the microstructure of the weld nugget zone and the thermal mechanically affected zone were refined as the welding speed increasing when the rotate speed is constant. As the welding speed increasing the strength of extension of the welded joint is increasing at first and then stable basically. but the yield strength had no obvious change.

Mechanical Properties and Fracture Toughness of Aluminum Vessels by Friction Stir Welding

2004 ◽  
Author(s):  
Masahito Mochizuki ◽  
Masao Toyoda ◽  
Masayuki Inuzuka ◽  
Hidehito Nishida
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Crack Initiation ◽  
Base Metal ◽  
Welded Joint ◽  
Stir Zone ◽  
Crack Initiation And Propagation ◽  
Friction Stir ◽  
Fine Grained ◽  
Initiation And Propagation

Mechanical properties and fracture toughness in friction stir welded joint of vessels of structural aluminum alloy type A5083-O are investigated. Welded joint from 25 mm-thick plate is fabricated by one-side one-pass friction stir. Charpy impact energy and critical crack-tip opening displacement (CTOD) in friction stir weld are much higher than those of base metal or heat-affected zone, whereas mechanical properties such as stress-strain curve and Vickers hardness do not have a conspicuous difference. Effects of microstructure on crack initiation and propagation are studied in order to clarify the difference of fracture toughness between stir zone and base metal. Both tensile test and bending test show that the fine-grained microstructure in stir zone induces to increase ductile crack initiation and propagation resistance by analyzing fracture resistance curves and diameter of dimples in fracture surface. It is found that high fracture toughness value in stir zone is affected fine-grained microstructure by friction stirring.

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