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Title Effect of forging pressure on the microstructure of linear friction welded Inconel 738 superalloy
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Date Accessioned
Discipline/Department Mechanical and Manufacturing Engineering
Degree Level masters
University/Publisher University of Manitoba
Abstract Inconel 738, which is a nickel base superalloy used for hot section components of aircraft and industrial turbines is difficult to fabricate and repair by fusion welding due to its susceptibility to heat affected zone (HAZ) intergranular cracking. Crack-free joining of the difficult-to-weld alloy is currently achieved by using linear friction welding (LFW). Nevertheless, oxidation along the joint during LFW is a major problem. Information about the effect of process parameters on the microstructural evolution of linear friction welded nickel base alloys is very limited. In this work, the effect of forging pressure on the microstructure of linear friction welded Inconel 738 was studied. The results as elucidated in this work showed that increased forging pressure caused strain-induced rapid solidification of metastable liquid, which resulted in complete elimination of deleterious liquid phase oxides in bonded material contrasting the generally accepted view that assumes extrusion of solid state oxides during LFW.
Subjects/Keywords Friction welding; Forging pressure; Oxidation; Nickel superalloy; Re-solidified eutectics; Inconel 738; Recrystallization; Weld temperature; Vacancy diffusion; Pipe diffusion
Contributors Chaturvedi, Mahesh (Mechanical and Manufacturing Engineering) Ojo, Olanrewaju (Mechanical and Manufacturing Engineering) (supervisor); Richards, Norman (Mechanical and Manufacturing Engineering) Shalaby, Ahmed (Civil Engineering) (examiningcommittee)
Country of Publication ca
Record ID handle:1993/8125
Repository manitoba
Date Indexed 2019-01-09
Issued Date 2012-07-27 00:00:00
Note [note] October 2012;

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welding process……….………46 Figure 2- 15: (a) Layout of continuous drive friction welding (b) parameters on continuous drive friction welding………………………………………………………..49 Figure 2-16: Basic principle of linear friction welding process…

…53 Figure 2- 17: The four phases of the linear friction welding process…………………....54 Figure 2- 18: Illustration of friction stir welding………………………………………...57 Figure 4-1: (a) SEM micrographs of solution-heat-treated (SHT) IN 738…

…Figure 2-12: Source – Welding Journal. Reprinted with permission. Figure 2-14: Source – Welding Journal. Reprinted with permission (July 06, 2012). Figure 2-15: Source – “Robotic Friction Stir Welding” Reprinted with permission from Emerald…

…by liquid and eventually de-cohesion along one of the solid-liquid interfaces under the influence of oncooling tensile stresses [2, 3]. In the quest to achieve crack free welding of IN 738, linear friction welding, which was presumed to be a…

…solid state process with the potential for 1 joining aerospace components, was used to produce welds of nickel base alloys devoid of cracks [4-7]. Linear friction welding is a self-regulating process that uses heat generated by the…

welding parameters on microstructural changes induced during the linear friction welding process. This research was initiated to study the effect of forge pressure on the microstructure of linear friction welded IN 738. Optical, scanning electron and…

…reduction of deleterious oxides along the weld line that could jeopardize the weld integrity of the linear friction welded specimens. Information obtained from this research will be useful in optimizing the forge pressure during the linear friction welding

…discussed, and a discussion on friction welding processes will be presented. 2.2 Physical Metallurgy of IN 738 Inconel 738 is a nickel base superalloy strengthened through both solid solution and precipitation hardening. It possesses excellent creep-rupture…

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