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1

Effect of Welding Conditions on Microstructural Evolution of Friction-Stir-Welded Ti-Cu Plate

Lee Yong-Jae, Jeong Won-Ki, Lee Seung-Jun, Fujii Hidetoshi, Shin Se Eun, Lee Dong-Geun

Archives of Metallurgy and Materials

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2023

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Vol. 68, iss. 1

131--135

EN

Fusion welding of Ti-Cu is difficult because of big difference of melting points and formation of brittle intermetallic compounds. Friction stir welding is carried out by solid-state joining, thermo-mechanical stirring, and friction heat. Ti-Cu FSW dissimilar welding can supply a very sound joint area with a few intermetallic compounds. Optimized welding process conditions are essential to obtain suitable microstructure and mechanical properties of welded zones. Different welding speeds affect the evolution of microstructure and mechanical properties due to changes of input heat and internal stored deformation energy. The correlation of microstructure and mechanical properties of Ti-Cu welded zone according to welding speeds were investigated and analyzed. As the higher the welding speed, the lower the heat input and the lower the temperature rise. Ti-Cu 75 has the smallest grain size at 13.9 μm, but the optimum mechanical properties and the integrity of welding were shown in Ti-Cu 50.

2

Effect of fibre laser welding parameters on the microstructure and weld geometry of commercially pure titanium

Abdulridha M.M., Jilabi A.S.J.A.Z.

Archives of Materials Science and Engineering

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2022

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Vol. 117, nr 1

34--41

EN

Purpose: The primary purpose of the study was the metallurgical characterization of laser welds. The weldability of commercial production of pure titanium and titanium alloy (CP-Ti) has also been examined. Design/methodology/approach: In this research, the laser fibre method was used to weld sheets of pure titanium, and then microscopy and scanning electron microscopy were used to study the changes in the microstructure, the depth of weld penetration and the width of the weld area with changing welding parameters. Findings: The results proved that increasing the laser power significantly increases the depth of weld penetration and weld width. When the heat input is increased, the shape of the weld pool changes from a V shape to an hourglass shape. It was also observed that the depth of the crater formed increases with the increase in the laser power due to the increase in the melting and evaporation of the weld metal. Increasing the welding speed also has a negative impact on the weld geometry because it reduces the heat input and absorption of laser energy by the weld metal and thus reduces the melting of the metal. The microstructure of the fusion zone consists of acicular α. Fine grains formed in the weld centre at low heat input; the granules became columnar-like. Since commercially pure titanium contains a small amount of beta-phase stabilizers, the cooling rate is extremely high for martensite to occur. Research limitations/implications: In the future, it is recommended to study the effect of changing welding parameters on the mechanical properties of pure titanium because of its great importance in industrial and medical applications. Originality/value: Studying the effect of changing laser power and welding speed on the metallurgical properties of pure titanium, and consequently its effect on the mechanical properties of welds.

3

The effect of welding fixtures on welding distortions

Vural M., Muzafferoglu H. F., Tapici U. C.

Journal of Achievements in Materials and Manufacturing Engineering

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2007

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Vol. 20, nr 1-2

511-514

EN

Purpose: of this paper is to examine the effect of welding fixture used to prevent the distortions during cooling process utilizing a robot controlled gas metal arc welding method on cooling rate and distortions of welded structures. Design/methodology/approach: Using a specially designed welding fixture for a welded steel structure, six different types of AISI 1020 steel specimens are tested in three different welding speeds and two different cooling conditions either at fixture or without using fixture. Findings: designed fixture is reduced amount of distortions. The preheating effect of previous weld on the next weld has increased distortions on the other side of part. Increase in distortions is directly proportional to the increase in welding speed which affects the weld heat input. Research limitations/implications: the study can be repeated on more complex structures and fixtures. Practical implications: the study has shown that the fixture design has an important effect on cooling rate of the welded parts. Originality/value: most of papers in literature is about fixture design methodology, but this paper is an example of demonstration for a practically applied welding fixture.