The Welding Surface and Mechanical Characteristics in Friction Stir Welding for 5456-H116 Alloy

Since the invention of the friction stir welding, several studies have been conducted to understand the influence of process parameters on the microstructural, thermal and mechanical characteristics to improve the weld quality. Banded structures better known under the name of "onion rings" are one of phenomena that appear in the microstructure during this process. The welding parameters leading to their appearance as well as their effect on the quality of the joint are still subject to much research with different conclusions. In this context, the objective of this research work is to determine various characteristics of the ‘onion rings’ and correlate them to processing conditions.

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Effect of Shoulder–Workpiece Interference Depth on the Quality of Friction Stir Welding of AA7075-T6 Aluminium Alloy

Association of Arab Universities Journal of Engineering Sciences ◽

10.33261/jaaru.2019.26.1.020 ◽

2019 ◽

Vol 26 (1) ◽

pp. 150-159

Author(s):

Abbas Akram Abbas ◽

Hazim H. Abdulkadhum

Keyword(s):

Friction Stir Welding ◽

Aluminium Alloy ◽

Welding Process ◽

High Strength ◽

Filling Defect ◽

Welding Quality ◽

Left Hand ◽

Friction Stir ◽

Tool Shoulder ◽

Welding Surface

The joining of high strength aluminium alloy AA7075-T6 sheets of 3 mm thickness was an attempt utilizing friction stir welding process. The effect of interference depth between tool shoulder and surface workpiece on the welding quality and its effect on the mechanical and metallography properties of welded joints were studied. This process is carried out using a composite tool consists of a concave shoulder made of H13 tool steel and cylindrical left-hand thread with 1mm pitch pin (probe) made of cobalt-based alloy MP159. The dimensions of tools were 14mm shoulder diameter and the pin has 5mm diameter and 2.7mm length. The tool rotation speed and welding speed were 981 rpm 169 mm/min respectively, and the tilt angle was 2°. The range of interference depth between the shoulder and workpiece was selected (0.05, 0.1, 0.15, 0.2, 0.25, and 0.3) mm. various tests were executed to evaluate the welding quality. The results show that lack of filling defect appeared on the welding surface at the interference depth 0.05 mm. An invisible tunnel and lack of penetration in the bottom of the stir zone appeared when the interference depths were 0.1 mm and 0.15 mm. Defect-free welds obtained when interference depths were (0.2, 0.25, and 0.3) mm. The welding efficiency of the defect-free welds was in the range (85.3-92.3%) depending on the ultimate tensile strength of the parent alloy.

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Possibilities for Application of Friction Stir Welding Process to Titanium TiGr2

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1138.125 ◽

2016 ◽

Vol 1138 ◽

pp. 125-132

Author(s):

Radu Cojocaru ◽

Lia Nicoleta Boţilă ◽

Cristian Ciucă ◽

Victor Verbiţchi

Keyword(s):

Friction Stir Welding ◽

Mechanical Characteristics ◽

Welding Process ◽

Experimental Program ◽

Metallic Materials ◽

Butt Welding ◽

Friction Stir ◽

Good Corrosion Resistance ◽

Innovative Method ◽

Welding Joints

The interest in friction stir welding (FSW) of different categories of light metallic materials, including titanium and its alloys, has growing in recent years.Due to favorable ratio between strength and density, titanium and its alloys have increasingly used in applications in priority areas (e.g. aeronautics and in aerospace). Having the best impact strength and good corrosion resistance, these materials find applications in chemistry, nuclear and military technology.This paper present the results obtained at friction stir butt welding of TiGr2 sheets with thickness 4mm.The experimental program has developed using three categories of welding tools: with smooth cylindrical pin and flat shoulder, with tapered pin and flat shoulder, respectively with tapered pin having four plane chamfers and flat shoulder. The welding experiments have made using combinations of tools and welding parameters.The control of FSW welding process of titanium TiGr2 sheets has done using an innovative method namely infrared thermography technique.The research program has focused on development of some welding tools and welding regimes correlated with obtaining some of better mechanical characteristics for welded joints.Results obtained to the friction stir butt welding of titanium TiGr2, lead to conclusion that welding joints without defects and with good mechanical characteristics can be obtained, if are known and met the specific requests regarding applying of FSW process to this type of material.

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