Journal of Materials Processing Technology 210 (2010) 2215–2222 Contents lists available at ScienceDirect Journal of Materials Processing Technology journal homepage: www.elsevier.com/locate/jmatprotec Experimental investigation and 3D finite element prediction of the heat affected zone during laser assisted machining of Ti6Al4V alloy Jihong Yang a,∗ , Shoujin Sun a , Milan Brandt b , Wenyi Yan c a CAST Cooperative Research Centre, Faculty of Engineering and Industrial Sciences, Swinburne University of Technology, PO Box 218 (H66), Hawthorn, VIC 3122, Australia b School of Aerospace, Mechanical and Manufacturing Engineering, RMIT University, Bundoora, VIC 3083, Australia c Department of Mechanical and Aerospace Engineering, Monash University, Clayton, VIC 3800, Australia article info Article history: Received 18 April 2010 Received in revised form 10 August 2010 Accepted 12 August 2010 Keywords: Finite element method Titanium alloy Thermomechanical processing Laser heating Heat affected zone abstract An experimental study was conducted to characterize the heat affected zone produced when laser heat- ing a Ti6Al4V alloy plate workpiece. The emissivity and absorptivity of the Ti6Al4V alloy were determined experimentally. A 3D transient finite element method for a moving Gaussian laser heat source was devel- oped to predict the depth and width of the heat affected zone on the Ti6Al4V alloy workpiece. There was a close correlation between the experimental data and the simulation results. It was found that the depth and width of the heat affected zone were strongly dependent on the laser parameters (laser power, laser scan speed, the angle of incidence and the diameter of the laser spot) and material properties (thermal conductivity, specific heat and density). Parametric studies showed that the depth and width of the heat affected zone increased with an increase in the laser power and decreased with an increase of the laser spot size and the laser scan speed. The thermal model can be used to determine the laser parameters for a given cut geometry that will yield no residual heat affected zone in the material after cutting. This provides the basis to optimize and improve laser assisted machining technique. © 2010 Elsevier B.V. All rights reserved. 1. Introduction Titanium alloys have been widely used in aerospace, biomedical and automotive industries because of their high strength-to-weight ratio and superior corrosion resistance at room and elevated tem- peratures. Ti6Al4V is the most popular titanium – alloy – its total production is about half of all titanium alloys. Aluminum (Al) is added to the alloy as the -phase stabilizer and hardener due to its solution strengthening effect. Vanadium (V) stabilizes the ductile -phase, providing hot workability of the alloy. However, titanium alloys are difficult to machine due to their high strength, low ther- mal conductivity and high chemical reactivity. Rahman et al. (2006) concluded that conventional machining of titanium alloys is a low productivity process with high materials running costs, such as the costs of tool and coolant. Laser assisted machining (LAM) of aerospace alloys was initially suggested by Rajagopal et al. (1982). Laser assisted hot machin- ing of ceramics was developed by Konig and Zaboklicki (1993). Chryssolouris et al. (1997) reported that LAM had been consid- ered as an alternative to conventional machining of hard and/or difficult-to-process materials. Since 1982 the LAM technique have ∗ Corresponding author. Tel.: +61 3 92144342; fax: +61 3 92145050. E-mail address: jyang@swin.edu.au (J. Yang). been used to machine such as stainless steel (Anderson and Shin, 2006), Inconel 718 (Anderson et al., 2006), titanium alloys (Sun et al., 2008) metallic alloys and silicon nitride ceramics (see, e.g., Lei et al., 1999; Rozzi et al., 2000). During the LAM process a laser beam heats the workpiece material directly ahead of a conventional cut- ting tool. The heat from the laser beam reduces the strength of the workpiece material along the machine tool path. Therefore, the material can be cut more easily with a lower cutting force. As a result, LAM leads to a higher material removal rate, an increased productivity, and a longer tool life when compared with conven- tional machining. A major feature of the LAM process is the number of parame- ters, which must be controlled during cutting. In addition to the conventional cutting parameters (cutting speed, feed rate, depth of cut, type of tool), there are laser parameters and also the inter- action parameters between the relative position of the laser beam and cutting tool. Modeling of LAM is of great importance, since a better process understanding will allow process optimization and control. An accurate model of an underlying experimental sys- tem is necessary to conduct parametric studies to characterize the temperature distribution during thermally assisted machining. Furthermore, this heat-assisted process induces a detrimental heat affected zone (HAZ) in the part. The HAZ can be determined from the investigation of the laser heating, which can assist the design of the following machining so that the entire HAZ can be removed by machining. 0924-0136/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.jmatprotec.2010.08.007