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Write 7 pages thesis on the topic laser welding of dissimilar metals

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Write 7 pages thesis on the topic laser welding of dissimilar metals. The joints are positioned with respect to the high laser using power machine. The table is scanned along the (Z) direction to form continuous weld, three sets of continuous welds are carried out with varying a laser power, laser scan speed, the focus position, all the welding process were in the constant flow rate of gas and Nitrogen gas was used as shielding gas.

The process was taken place of all samples after welding by using the x-ray machine, the radiographic equivalent factors were selected according to metal and the thickness of the samples. The results show some welding defects in some samples and the rest of the samples were acceptable.

Tensile test of welding joint was done on Zwick Roell universal test machine controlled by computer, the test was performed at the room temperature to determine the tensile strength and the yield strength.

The samples were cross-sectioned, ground by using (80, 120, 320, 600, 1200) grinding paper and polished by Diamond suspension for metallurgical examination. The mounted specimens were etched in a solution comprised of 50% Hydraulic acid + 25% Nitric acid + 25% water and ethyl alcohol for 20–60 s until the microstructure was revealed. The microstructure and microhardness distribution were characterized by optical microscope.

The effect of heat input as a function of laser power, H, = P/S, was clarified using type 316L and low carbon steels. Both the welding speed and focus position were kept constant (1.2mm/min) and (-1.5 mm) respectively.

The penetration depth increased with increasing laser power. Complete penetration for the 3 mm base metal was obtained at laser power equal to or greater than 2kw. Laser power has a less influence on both the weld profile and (HAZ) width.

The focus position is the distance between the specimen surface and the optical focal point. In order to study its effect on both penetration depth and weld profile, complete penetration These metals were received in the form of plates of 350×10×3 mm from the vendors and were precisely machined on the Milling machine in the mating areas of both the metals to avoid the gap between the metals which lead to misalignment.