Welding process features

Make a collection of broken plastics products, then assess from the fracture appearance (i) Whether fracture was due to yielding, fatigue or environmental stress cracking (ii) whether the major load system was tension, bending or torsion (iii) whether there were processing features involved such as weld lines and orientation (iv) whether design faults could have been remedied. 

The triggering mechanism for the corrosion process was localized depassivation of the weld-metal surface. Depassivation (loss of the thin film of chromium oxides that protect stainless steels) can be caused by deposits or by microbial masses that cover the surface (see Chap. 4, Underdeposit Corrosion and Chap. 6, Biologically Influenced Corrosion ). Once depassivation occurred, the critical features in this case were the continuity, size, and orientation of the noble phase. The massive, uninterrupted network of the second phase (Figs. 15.2 and 15.21), coupled... 

In order to identify the production processes required to produce a particular product you need a production requirement in the form of product specifications which define the features and characteristics of the product that are to be achieved. By studying these specifications you will be able to identify the processes required to turn raw materials and bought-out components into a finished product. With manufactured products the processes may include machining, welding, fabrication, assembly, forming, plating, painting, heat treatment, etc. 

Plasma Arc Welding. In the transferred-arc mode of the PAW process, shown in Figure lc, the arc is between a nonconsumable electrode and the base metal, in a manner similar to the GTAW process. The unique feature is the flow of inert gas around the electrode and through a restricted orifice, which constricts the arc to form a plasma jet. A second, outer stream of shielding gas protects the molten metal from atmospheric contamination. In the nontransferred arc mode of the PAW process, the arc is between the electrode and the constricting orifice. This mode is used for plasma spraying... 

---