An investigation into the effect of welding parameters on fatigue crack growth rate and fracture toughness in friction stir welded copper sheets

2015 ◽  
Vol 232 (3) ◽  
pp. 191-203 ◽  
Author(s):  
Ali Alavi Nia ◽  
Ali Shirazi
Keyword(s):  
Fracture Toughness ◽  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Heat Affected Zone ◽  
Base Material ◽  
Welding Process ◽  
Stir Zone ◽  
Welding Parameters ◽  
Friction Stir

In the present study, the effect of various factors of friction stir welding including rotational and traverse speeds of tool and in fact, the amount of the heat transferred within welding was evaluated on the resistance to fatigue crack growth and fracture toughness in different zones of welding copper sheets. In order to better assess these two properties, other mechanical properties such as tensile strength and hardness were also studied and the microstructure of different zones of welds was investigated using optic and electron microscopies. By doing this study, it became clear that the less the heat transferred to the plunging during the welding process, the better properties the resulting welds will have which well justifies the use of cooling in this study. Transferring heat to plunging causes the growth of grains in various zones and can cause the fatigue crack growth in heat-affected zone to increase averagely about 4.2 times the base material for different Δ K. In contrast, the occurrence of dynamic recrystallization in the stir zone as well as fragmentizing and alignment of grains in this zone can increase the resistance to fatigue crack growth up to 9-fold the resistance of the base material. The other interesting result of this study was that although the properties of stir zone improve by increasing the number of welding passes, the properties of its weakest zone i.e. the heat-affected zone will decline.

Fatigue Crack Growth on FSW AA2024-T3 Aluminum Joints

2012 ◽  
Vol 498 ◽  
pp. 126-138 ◽  
Author(s):  
Pedro Miguel Guimarães Pires Moreira ◽  
Paulo Manuel Salgado Tavares de Castro
Keyword(s):  
Growth Rate ◽  
Fatigue Crack ◽  
Solid State ◽  
Crack Growth Rate ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Base Material ◽  
Welding Process ◽  
Butt Joints ◽  
Friction Stir

Friction stir welding (FSW) is a solid-state joining process which emerged as an alternative technology to join high strength alloys that were difficult to weld with conventional techniques, [1]. Developments of this technique are being driven by aeronautic, aerospace and railway industries. An advantage of this joining technique is its low heat input when compared with arc welding processes. This feature allows the achievement of high mechanical properties, low distortion and low residual stresses, [2]. Also, since it is a solid-state welding process, hydrogen cracking or heat affected zone (HAZ) softening phenomena are limited. This paper presents a study of fatigue crack growth behaviour of friction stir welded butt joints of AA2024-T3, aluminium commonly used in riveted aeronautic fuselage structures. Crack growth studies are often carried out using uniform thickness joints, ASTM E647 [3]. Nevertheless, for some applications there is a need to join components with different thicknesses, which, under certain limits, can be welded using FSW. Crack growth tests on these joints are not standard. The present study concerns butt joints made using two plates with different thicknesses, 3.8mm and 4.0mm. The joints’ mechanical behaviour was studied performing static (tensile) and fatigue tests. The fatigue crack growth rate of cracks growing in different zones of the welded joint (nugget, heat affected zone - HAZ) and in base material was analysed. The microhardness profile was assessed in order to analyse the influence of the welding process in each weld zone. Further to higher static properties, welded joints present lower crack growth rate when compared with its base material.

Fracture Toughness and Fatigue Crack Growth Study of Friction Stir Welded Plates

2012 ◽  
Vol 12 (23) ◽  
pp. 2469-2473 ◽  
Author(s):  
Siti Nur Farhin Mokhtar ◽  
Azmi Abdul Wahab ◽  
Saravanan Karuppanan
Keyword(s):  
Fracture Toughness ◽  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Growth Study ◽  
Friction Stir

scholarly journals Fracture toughness and fatigue crack growth behavior of A3003/SUS304 lap friction stir welded joints

2015 ◽  
Vol 33 (1) ◽  
pp. 20-28
Author(s):  
Hidehito Nishida ◽  
Tomo Ogura ◽  
Ryoichi Hatano ◽  
Hirotaka Kurashima ◽  
Misuo Fujimoto ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Welded Joints ◽  
Growth Behavior ◽  
Crack Growth Behavior ◽  
Fatigue Crack Growth Behavior ◽  
Friction Stir

Evolution of Fatigue Crack Growth Phenomena in Friction Stir Welded AA2xxx Alloys

2021 ◽  
Vol 875 ◽  
pp. 227-237
Author(s):  
Wali Muhammad ◽  
Wilayat Hussain ◽  
Hamid Zaigham ◽  
Nouman Zubair
Keyword(s):  
Fatigue Crack ◽  
Friction Stir Welding ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Welding Process ◽  
Fatigue Properties ◽  
Crack Growth Behavior ◽  
Friction Stir ◽  
Structural Applications ◽  
The Uk

Aluminum 2xxx alloys have been one of the primary materials for the structural applications of aerospace and transportation industry because of their performance, manufacturing and reliable inspection techniques. Welding is very important in the manufacturing process of structural parts and is now known as the most vital process in the manufacturing route. A relatively new process of joining of materials is friction stir welding process, which was invented by The Welding Institute (TWI) in the UK in 1991. The friction stir welding is mainly employed in aerospace, marine and transportation fields that have high safety requirements. The failure by fatigue is the dominant failure mode for structural weld joints. Since fatigue failure of parts accounts for 50 to 90% of all failures, it is of great significance to understand the fatigue properties of friction stir welded joints. The aim of this overview is to summarize the current research on fatigue crack growth behavior of friction stir welded AA2xxx alloys and critical attention is payed to the damage tolerance performance of friction stir welded aluminum joints that can be affected by welding process parameters, residual stress, stress ratio, environment and post weld treatments.

Different Microstructures in the HAZ of Double Submerged Arc Welded Pipelines and How They Influence the Fatigue Crack Growth

2013 ◽  
Author(s):  
Bernd Maier ◽  
Christoph Guster ◽  
Richard Tichy ◽  
Werner Ecker
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Base Material ◽  
Welding Process ◽  
Stress Sensitivity ◽  
Crack Growth Behaviour ◽  
Hsla Steels ◽  
Stress Ratios ◽  
Submerged Arc

To meet the cost and weight reduction requirements in welded structures, the application of high-strength low-alloy (HSLA) steels also increases in the field of pipeline engineering. However, in comparison to low-strength steels these materials are more susceptible to notches or initial cracks. Therefore, an extensive investigation of fatigue crack growth behaviour in the different microstructural zones of the heat-affected zone (HAZ) is necessary for an appropriate lifetime evaluation of welded pipes. For this purpose, fracture mechanics parameters like thresholds and crack growth rates in the three characteristic microstructural zones of the HAZ as well as in the base material are characterized. The different microstructures are reproduced with a Gleeble thermal simulator system using the same heating curves as measured previously during the welding process of a double submerged arc welded pipeline. The effect of varying stress ratios R on the crack growth threshold and the crack growth curves is also assessed. This knowledge about the mean stress sensitivity is needed for estimating the influence of residual stresses stemming from different manufacturing processes like welding and post-welding treatments, which is essential for a reliable, damage tolerant application of HSLA steels in pipelines.

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