In this present work, laser welding experiments were carried out on 1 mm thin Ti6Al4V sheets using a low power Nd-YAG laser machine without using any filler wire and without edge preparation of welding specimens. The influence of different major process control parameters such as welding speed and power on the yield parameters like temperature field, weld bead geometry, microstructure, and mechanical properties are critically investigated. Experimental results are compared in detail with the simulated results obtained using a commercial 3D finite element model. In the simulation model, temperature-dependent thermal and mechanical properties of plates were considered. The temperature readings were recorded with the aid of K type thermocouples. Forced convection has been assumed near weld zone region because of the movement of the shielding gas. Appreciable agreement is found between the experimental and the simulated temperature fields in most of the cases with few exceptions. These deviations on few occasions may be due to the presence of uncertainties inherently present in the experimental domain and uncertainties in the subsequent temperature sensing techniques by the thermocouples. In addition, annealing has been done at 950 °C, 980 °C, and 1010 °C for one selected parameter (192 W, 6 mm/s). The tensile strength of the samples annealed at 980 °C has been found to be 1048 MPa and it is 3% to 4% higher than that of the usual welded samples.

Dissimilar welding potentially has great importance for many industries. Joining of two different alloys is very challenging. In this paper, an attempt was made to produce a reliable joint between Nickel-based superalloy with stainless steel using the gas tungsten arc welding process with nickel-based filler wire. Post-weld heat treatment was executed at 700°C for 2 h. A critical comparison was made between the post-weld heat-treated samples and as-welded samples. The tensile test indicates that the strength of the joint is higher than the weaker base metal (Stainless Steel). The macrostructure and microstructure show proper fusion and bonding among the parent metals and filler wire. There is a formation of the partially melted zone at fusion boundary and secondary phase (Niobium-rich phase) at a region adjacent to the fusion boundary on heat-affected zone of Inconel side. It was also observed that the post-weld heat-treated samples have a significant reduction in the secondary phase. Vickers’ microhardness value indicates that the secondary phase has a higher value of hardness both in as-weld condition and post-weld heat treatment condition. Thus, Nickel-based filler wire is a compatible filler wire for the dissimilar joint.

Investigation of microstructure and mechanical properties of titanium alloy sheet using low power Nd-YAG laser welding process

In TIG (Tungsten Inert Gas) welding process Welding Current and Speed are important parameters. This paper investigates into microstructure and some mechanical properties of TIG welded Ti-6Al-4V Titanium alloy. Welding was carried by varying welding current and speed while keeping other parameters constant. It investigates into microstructures of different zone around the welded joint and found that microstructures become coarser near the Fusion Zone (FZ) and Heat Affected Zone (HAZ) and β-Phase predominant at FZ. The analysis of microhardness shows that as we move from base metal to weld centreline hardness value increases and maximum value of hardness was found at Fusion Zone. Highest value of hardness was found to be 472 HVN which is very high compare to base metal which is at low speed and high current i.e. of Sample S3.