Correlation between microstructures and mechanical properties of high-speed friction stir welded aluminum hollow extrusions subjected to axial forces

2018 ◽  
Vol 34 (1) ◽  
pp. 102-111 ◽  
Author(s):  
Xiangqian Liu ◽  
Huijie Liu ◽  
Tianhao Wang ◽  
Xiangguo Wang ◽  
Si Yang
2019 ◽  
Vol 255 ◽  
pp. 126543 ◽  
Author(s):  
Huaibo Deng ◽  
Yuhua Chen ◽  
Timing Zhang ◽  
Shanlin Wang ◽  
Limeng Yin ◽  
...  

2015 ◽  
pp. 241-246
Author(s):  
Taiki Nakata ◽  
Kazunori Shimizu ◽  
Yasunobu Matsumoto ◽  
Satoru Hanaki ◽  
Shigeharu Kamado

2011 ◽  
Vol 70 ◽  
pp. 135-140 ◽  
Author(s):  
G. Le Louëdec ◽  
M.A. Sutton ◽  
Fabrice Pierron

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.


Materials ◽  
2019 ◽  
Vol 12 (24) ◽  
pp. 4211 ◽  
Author(s):  
Anton Naumov ◽  
Iuliia Morozova ◽  
Evgenii Rylkov ◽  
Aleksei Obrosov ◽  
Fedor Isupov ◽  
...  

The objective of this study was to investigate the effect of the high welding speed on the mechanical properties and their relations to microstructural characteristics of butt friction stir welded joints with the use of 6082-T6 aluminum alloy. The aluminum sheets of 2.0 mm thick were friction stir welded at low (conventional FSW) and high welding speeds (HSFSW) of 200 and 2500 mm/min, respectively. The grain size in the nugget zone (NZ) was decreased; the width of the softened region was narrowed down as well as the lowest microhardness value located in the heat-affected zone (HAZ) was enhanced by HSFSW. The increasing welding speed resulted in the higher ultimate tensile strength and lower elongation, but it had a slight influence on the yield strength. The differences in mechanical properties were explained by analysis of microstructural changes and tensile fracture surfaces of the welded joints, supported by the results of the numerical simulation of the temperature distribution and material flow. The fracture of the conventional FSW joint occurred in the HAZ, the weakest weld region, while all HSFSW joints raptured in the NZ. This demonstrated that both structural characteristics and microhardness distribution influenced the actual fracture locations.


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