Titanium and their alloys have high strength to weight ratio, good corrosion resistance and high melting point temperature lead to their application in engineering. Ti-6Al-4V alloy has been widely used in medical, chemistry and aerospace industries. In this research, laser welding of Ti-6Al-4V sheet with the thickness of 1.7 mm performed using a 400 W pulsed Nd:YAG laser. The effects of laser peak power, pulse duration and laser pulse energy on the weld bead profile, weld microhardness, tensile strength and microstructure were studied. Results showed that by increasing laser peak power, decreasing pulse duration and increasing laser pulse energy, the weld penetration increases. Metallurgical observations revealed that welded zone comprises of acicular αˊphase within prior coarse βgrains. Microhardness distribution is more uniform in welded zone. The microhardness value in the welded zone is the highest which is attributed to high martensitic phase content in the welded zone. The ultimate tensile strength (UTS) values show the variation from 649 to 998 MPa in the Nd:YAG laser welded samples.
