5. Parent material; 6. Welding method; 7. Welding of structural components; 8. Welding of pressure-bearing parts. 9. Welding procedure qualification.
Welding is used to connect materials, and the quality assurance of welded joints is the most critical, and its mechanical properties must be greater than or equal to the minimum mechanical properties of the base material.
You can find many things to write from the welding manual or online.