Magnesium alloys are becoming important material for light weight car body, due to their low specific density but high specific strength. However they have a poor weldability, caused by high oxidization tendency and low vapour temperature. In this study, the welding performance of magnesium alloy was investigated for automobile application. The material was rolled magnesium alloy sheet contains 3wt%Al, 1wt%Zn and Mg balance. The effects of filler wire addition was investigated on 2kW Nd:YAG laser welding. For the results, the mechanical properties of welded specimen were similar with base metal in laser welding with and without filler wire. The bridging ability was improved with filler wire without weld properties deterioration on laser welding of magnesium alloy.

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A jack-up rig or a self-elevating unit is a type of mobile platform that consists of a buoyant hull fitted with a number of movable legs, capable of raising its hull over the surface of the sea. The buoyant hull enables transportation of the unit and all attached machinery to a desired location. Once on location the hull is raised to the required elevation above the sea surface on its legs supported by the sea bed. The legs of such units may be designed to penetrate the sea bed, may be fitted with enlarged sections or footings, or may be attached to a bottom mat. Generally Jack up rigs are not self-propelled and rely on tugs or heavy lift shipsfor transportation. Formability problems in offshore structure construction where particularly high-strength steels are used for chords and racks. Attainment of mechanical properties is not usually difficult, although procedural trials are advisable. Fatigue cracking is probably the major cause of service failure of jack-up rigs, and the use of high-strength steels, which permits higher static stress limits, can exacerbate this problem. Roll forming process is one of the most widely used processes in the world for forming metals. It can manufacture goods of the uniform cross section throughout the continuous processing. However, process analysis is very difficult because of the inherent complexity. Therefore, it is time-consuming and much money is needed for manufacturing goods. In order to overcome this difficulty, a new computational method based on the rigid-plastic finite element method is developed for the analysis of roll forming process.