**3. Processes of metal forming: forging, extrusion, KOBO extrusion, rolling, and joining: friction stir welding. Mechanical properties, microstructure, and quality of the final product. Examples of applications**

The analysis of magnesium alloys and their possibilities of deformation by plastic forming shows that they are prospective due to the development of a number of new technologies. The purposefulness of work on the development of the plastic forming technique [34] is primarily determined by the better mechanical properties of plastically processed magnesium alloys compared with the cast ones. Now, there are main groups of magnesium alloys available for plastic deformation**:**

• *Mg-Al-Zn alloys—*The magnesium alloys Mg-Al-Zn are the most popular ones. Four basic alloys AZ31, AZ61, and AZ80 are distinguished. The alloy AZ31 shows relatively low mechanical properties, but it is weldable and perfectly suitable for rolling, stamping, and extrusion. This grade is used to produce sheet metal designed mainly for drawpieces. The alloys AZ61 and AZ80 are

*Metal Forming of Magnesium Alloys for Various Applications DOI: http://dx.doi.org/10.5772/intechopen.101034*

characterized by a larger content of alloyed components, and they show more advantageous mechanical properties. The alloy AZ61 is weldable, plastically worked by extrusion and forging methods. The alloy AZ80 demonstrates the best mechanical properties in the group of plastically worked alloys; however, its susceptibility to plastic working is relatively low. It is suitable for making only simple forgings.


Designing the processes of metal forming of structural elements made of magnesium alloys requires precise determination of the influence of process parameters on the microstructure and consequently on the mechanical properties of the manufactured elements. This is of particular importance when designing products in aviation [36, 37], automotive, medical, and other applications. Plastic forming tests carried out under laboratory and industrial conditions indicate that selected magnesium alloys can be formed especially in the process of rolling, forging, and extrusion. When forming AZ61, AZ80, and WE43 alloys, the temperature range is significantly limited, both at the beginning and the end of the deformation process. Therefore, to carry out plastic forming, especially forging, it is necessary to have devices that enable the process to be carried out in isothermal conditions. For AZ31 alloy, the range of temperatures of good formability is greater due to the greater tendency of this alloy to the recrystallization process.

The beneficial properties of magnesium alloys are obtained thanks to thermoplastic treatment. In magnesium alloys, an intensive process of dynamic recrystallization takes place during plastic deformation, which promotes grain refinement and improvement of mechanical properties. Plastic forming of magnesium and its alloys can be carried out, depending on the content of alloying elements, only in a narrow temperature range.

Examples of the use of magnesium alloys in the formation of products/semifinished products in the processes of plastic forming and joining processes involving plastic deformation (friction stir welding) show the enormous potential of these materials and the clear benefits of using these technologies in the forming of various types of products.

### **3.1 Particularities of metal forming processes of Mg alloys**
