Solid state joining of metals by linear friction welding: A literature review

Abstract

Linear friction welding (LFW) is a solid state joining process in which a joint between two metals can be formed through the intimate contact of a plasticised layer at the interface of the adjoining specimens. This plasticised layer is created through a combination of frictional heating, which occurs as a result of pushing a stationary workpiece against one that is moving in a linear reciprocating manner, and applied force. The process is currently established as a niche technology for the fabrication of titanium alloy bladed disc (blisk) assemblies in aeroengines, and is being developed for nickel based superalloy assemblies. However, interest is growing in utilising the process in a wider range of applications that also employ non-aeroengine metallic materials. Therefore, it is the objective of this report to provide a broad view of the capabilities of the LFW process for joining metals. This review paper will cover relevant published work conducted to date on LFW. The basics of the process and the fundamental aspects of operating a LFW machine will first be described, followed by a description of the different materials that have been welded using the process. The review will then go on to describe the microstructural changes, including texture variations, and residual stresses that are produced as a result of the welding process.

Energy and Force Analysis of Ti-6Al-4V Linear Friction Welds for Computational Modeling Input and Validation Data

“…[2,4,8,11,13] The different zones are displayed in Figure 5(a). The WCZ which many authors suggest experiences significant recrystallization, [4,8,11,13] was found to have either a widmanstatten and/or martensitic microstructure, as shown in Figures 5(b) and (c), respectively. The WCZ was then followed by a TMAZ.…”

“…[4,8,11,12] Computational models are particularly useful as they provide a means of predicting what happens at the weld interface in the rapidly evolving process. However, the models are limited by a lack of data [13] -in particular, the interface force, friction coefficient, and steady-state burn-off rate as a function of the process inputs for the different phases of a weld. This paper addresses these issues using a systematic design of experiments to determine the effects of the process inputs on the average values of these outputs for the different phases of the process for Ti6Al-4V linear friction welds.…”

Linear friction weld process monitoring of fixture cassette deformations using empirical mode decomposition

“…Furthermore, it should be noted that this work studies the reproducibility of the welds, hence, the analysis of the influence of the different phases on the weld is not a part of this study. The interested reader is referred to the papers by Vairis and Frost [5] and Bhamji et al [3], where the influence of the weld phases on the parameters is discussed in much greater detail. However, the methodology presented here can be easily extended to do such a mechanistic analysis of the weld parameters.…”

“…The friction generates heat, which is enough to make the material ductile. In the first instance the rubbing is used to remove the outer layer of material, this is called burn-off in this work and comprises what is generally known as the initial (conditioning, [3]), the transition and equilibrium (frictional, [3]) and the first part of the deceleration (forge, [3]) phases [5], see Fig. 2.…”

“…In Refs [2,3] the basics of the working of a linear friction welding machine for blisk manufacturing are explained. An adapted version of the working diagram that can be found in Ref.…”