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High strength alloys such as nickel and titanium and advanced engineering materials such as ceramics, composites are being developed and widely used in aerospace, automotive, medical and nuclear industries due its inherent physical-mechanical properties. However conversion these new materials into engineering products are always associated with machining. The machinability characteristics such as higher cutting force, higher cutting temperature, poor surface integrity and shorter tool life associated with these materials posing many challenges to the researchers, and hence considered as difficult to cut materials. Conventional methods of machining these materials are found to be uneconomical. In recent days, many attempts have been made to improve the machinability of these materials more effectively via use of external energy assisted machining. Among the various external energy assisted machining methods, laser assisted machining (LAM) has received the attention of researchers in the metal cutting domain and a few research was carried during the recent years. This paper is aimed to review and summarize the potential use of LAM for difficult to cut materials, current progress, benefits and challenges in laser assisted machining. In addition an optimization frame work to study the effect of laser parameters and machining process parameters on machinability performance is not reported which is applicable to industrial processes It is concluded that further experimental modeling and empirical techniques are required to create a predictive based models that gives good agreement with reliable experiments, while explaining the effects of many parameters, for machining of these difficult-to-cut materials..

The study aimed at investigating the microstructure and mechanical properties of Neodymium-Doped Yttrium Aluminum Garnet (Nd:YAG) laser welded high strength low alloy (HSLA) SA516 grade 70 boiler steel. The weld joint for a 4 mm thick plate was successfully produced using minimum laser power of 2 kW by employing a single pass without any weld preheat treatment. The micrographs revealed the presence of martensite phase in the weld fusion zone which could be due to faster cooling rate of the laser weldment. A good correlation was found between the microstructural features of the weld joints and their mechanical properties. The highest hardness was found to be in the fusion zone of cap region due to formation of martensite and also enrichment of carbon. The hardness results also showed a narrow soft zone at the heat affected zone (HAZ) adjacent to the weld interface, which has no effect on the weld tensile strength. The yield strength and ultimate tensile strength of the welded joints were 338 MPa and 549 MPa, respectively, which were higher than the candidate metal. These tensile results suggested that the laser welding process had improved the weld strength even without any weld preheat treatment and also the fractography of the tensile fractured samples showed the ductile mode of failure.

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Titanium alloys are widely used in aerospace industries, due to its high strength to weight ratio and light weight. This paper investigates high speed end milling of titanium alloy (Ti-6% Al-4% V) using carbide insert based end mill cutter. Effects of cutting forces during high speed machining of titanium alloys have got higher attention in selecting the optimal cutting conditions to improve the production and tool life. Due to Titanium alloy's low thermal conductivity, more heat concentration takes place on cutting tool during rough machining. The heat generated increases the temperature of the cutting tool and affect the surface integrity of the workpiece and also cause tool wear. In this study experiments have been carried out under dry cutting conditions. The cutting speeds selected for the experiments are 120, 150 and180 m/min. The depth of cuts and feed rate were selected to suit finish machining. For conducting the experiments single insert based cutting tool is used. Experiments were conducted based on the Taguchi's design of experiments, in order to analyse the effect of cutting parameters on cutting force, temperature and surface roughness. From this study it is found that depth of cut and feed rate have higher effect on cutting forces when compared to cutting speed whereas the effect of cutting speed has higher effect on temperature.