The Backing Bar Role in Heat Transfer on Aluminium Alloys Friction Stir Welding

2010 ◽  
Vol 636-637 ◽  
pp. 459-464 ◽  
Author(s):  
M.J.C. Rosales ◽  
N.G. Alcantara ◽  
Jorge Santos ◽  
R. Zettler
Keyword(s):  
Heat Transfer ◽  
Friction Stir Welding ◽  
Aluminium Alloys ◽  
High Strength Steels ◽  
High Strength ◽  
Advanced Materials ◽  
Mechanical Degradation ◽  
Great Effort ◽  
Friction Stir ◽  
Advanced High Strength Steels

Although new structural and advanced materials have been used in the automotive and aircraft industries, especially lightweight alloys and advanced high strength steels, the successful introduction of such materials depends on the availability of proven joining technologies that can provide high quality and performance joints. Solid-state joining techniques such as Friction Stir Welding (FSW) are a natural choice since their welds are produced at low temperatures, so the low heat input provides limited, slight distortion, microstructural and mechanical degradation. Great effort has currently been devoted to the joining of Al-Cu-Mg and the Al-Mg-Si alloys because of their high strength, improved formability, and application in airframe structures. FSW is a continuous, hot shear, autogenous process involving a non-consumable and rotating tool plunged between two abutting workpieces. The backing bar plays an important role in heat transfer from stir zone (SZ), which can influence the weld microstructure as well as the consolidation of material in the root of the join. This study aims at investigating issues concerning heat generation, within the SZ of friction stir welded aircraft aluminium alloys.

Coupled Temperature-Microstructure Model for Predicting Temperature Distribution and Phase Transformation in Steel for Arbitrary Cooling Curves

2020 ◽  
Vol 13 (3) ◽  
Author(s):  
Sandip K. Saha ◽  
Akhilesh Kumar
Keyword(s):  
Heat Transfer ◽  
Phase Transformation ◽  
Steel Plate ◽  
Plate Thickness ◽  
High Strength Steels ◽  
High Strength ◽  
Rolling Speed ◽  
Transfer Model ◽  
Advanced High Strength Steels ◽  
Quenching Time

Abstract This study aims at developing a numerical model that can be employed for simulating the thermomechanical treatment to develop the advanced high strength steels. The developed numerical method is used to calculate the heat transfer coefficient of the quenching medium during the continuous cooling of the steel using the inverse heat transfer model for predefined cooling paths. Further, the phase transformation models are used to predict the final microstructure of the steel plate. The cooling rate, plate thickness, and rolling speed are varied to evaluate the temperature and microstructure distribution in the steel plate. It is found that on increasing the quenching time, the transformation fraction from austenite to ferrite and bainite phases increases and the corresponding martensite fraction decreases. The temperature variation in the plate is significant due to the change in plate thickness and rolling speed for a given quenching time. The present model will be useful for designing process parameters to obtain desired microstructures in third-generation advanced high strength steels.

scholarly journals Assessment of the Advantages of Static Shoulder FSW for Joining Aluminium Aerospace Alloys

2014 ◽  
Vol 783-786 ◽  
pp. 1770-1775
Author(s):  
Hao Wu ◽  
Ying Chun Chen ◽  
David Strong ◽  
Philip Prangnell
Keyword(s):  
Friction Stir Welding ◽  
Temperature Distribution ◽  
Temperature Gradient ◽  
Systematic Study ◽  
Aluminium Alloys ◽  
High Strength ◽  
Heating Effect ◽  
Friction Stir ◽  
Aerospace Alloys ◽  
Symmetric Temperature

Stationary (or Static) Shoulder Friction Stir Welding (SS-FSW) is a variant of FSW that was developed primarily to improve the weldability of titanium alloys by reducing the through thickness temperature gradient. Surprisingly, SS-FSW has been largely ignored by the Al welding community because it is widely supposed a rotating shoulder is an essential aspect of the process and that the higher conductivity means the surface heating effect of the shoulder is generally beneficial. In the work presented it is shown that SS-FSW has major advantages when welding high strength aluminium alloys; including a reduction in the heat input, a massive improvement in surface quality, and a narrower and more symmetric temperature distribution, which leads to narrower welds with a reduced heat affected zone width and lower distortion. The reasons for these benefits are discussed based on a systematic study aimed at directly comparing both processes.

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