AbstractsEngineering

In this rapidly evolving industry, welding is the most important way to join the metals and other materials to each other. As an example, offshore pipe laying is one of the most applicable areas for welding. In this industry, welding plays main role and any defect in welding can lead to disastrous events.Offshore pipe laying is coupled strongly to the oil and gas industry for the extraction and transportation of hydrocarbons from the sea bed. A number of these pipe lines have two dissimilar layers. The inner layer is manufactured from a corrosion resistance alloy (CRA), however, the outer layer is normally a carbon-manganese steel which is cheap. If the inner and outer layer of the pipe are bonded metallurgically, they are called clad pipes. If these two layers are bonded mechanically, they are called, lined pipes. The type of welding in clad or lined pipes can be considered as dissimilar welds since these pipes consist of two dissimilar metal layers. Generally in welding technology, depending on the method of welding, a filler metal is chosen to provide the reasonable chemical and physical compatibility between the filler and base metal. In order to apply and investigate the compatible materials for the clad/lined pipes different filler wires could be used for each layer of the pipe, a superalloy for the inner part and a low carbon steel for the outer part. The compatibility of these two materials in terms of chemical and physical properties is the most important factor to avoid and minimize the introduction of microstructural defects in the weld metal especially at the interface of the two filler metals.