Kneeling for the explanation of several terms: alloy shrinkage, shrinkage stress, metal plastic forming process, forging forming and arc welding. thank you

Conditions of metal plastic forming: If it is under the unidirectional stress of particles, when the unidirectional stress reaches the yield point of the material, the particles will have the elasticity to enter plasticity and yield. However, if it is a multi-directional stress, the stress components need to conform to a certain relationship to enter the plastic state. This relationship is the yield criterion, that is, the plastic condition. At present, Tresca and Mises yield criteria are widely used, and the forming methods include rolling, extrusion, drawing, forging, stamping and so on. Forging forming is a kind of processing and forming method which uses forging machinery to exert pressure on metal blank to make it plastically deform, so as to obtain forgings with certain mechanical properties, shapes and sizes. Forging can eliminate as-cast porosity defects and optimize the microstructure of metal during smelting. At the same time, because the complete metal streamline is retained, the mechanical properties of forgings are generally better than those of castings of the same material. Forgings are mostly used for important parts with high load and bad working conditions in related machinery except for simple rolled plates, profiles or weldments. Arc welding: covered electrode arc welding is the most widely used welding method in industrial production. Its principle is to use the heat generated by arc discharge (commonly known as arc combustion) to melt the covered electrode and the workpiece, and form a weld after condensation, so as to obtain a firm joint welding process.