The first chapter summarizes the application and advantages of welding in the first section, the definition and classification of welding in the second section, the review questions in the second section, the basic knowledge of metal materials in the second section, the definition and classification of metal materials in the third section, the properties of metals in the fourth section, carbon steel in the third section, the review questions of ordinary low-alloy steel in the third section, the welding equipment and tools in the first section, and the basic knowledge of electricity saving and manual operation. Common machines for arc welding Section III. Overview of common machines for manual gas welding. The fourth chapter welding materials in the first quarter covered electrode, Welding wire Section 2 Common gas welding review questions Chapter 5 Basic knowledge of welding Section 1 Manual arc welding Section 2 Manual gas welding review questions Chapter 6 Welding technology Section 1 Welding joint type Section 2 Manual gas welding technology Review questions Section 2 Manual gas welding technology Review questions Chapter 7 Welding stress and deformation Section 1 Reasons for welding stress and deformation Section 3 Methods for reducing welding residual stress Section 3 Review questions on eliminating welding residual deformation Chapter 8 Welding defects and quality inspection Section 1 Welding defects Section II Review of Welding Quality Inspection Chapter IX Definition and classification of gas cutting first throttle cutting second throttle cutting process and conditions third throttle cutting process review Chapter X Welding safety technology Chapter XI Composition of thermal power plant and its production process Chapter XII Welding knowledge chart attached table 1 Chinese alphabet Schedule 2 Greek letters Schedule 3 Prefixes are used to form decimal multiples and decimal units Schedule 4 Common legal units of measurement Schedule 5 Common units conversion table Schedule 6 Common quantities, symbols and unit names Schedule 7 Common chemical element symbols Schedule 8 Chemical composition and mechanical properties of steel commonly used in power plants Schedule 9 Main technical data of electric welding machines Schedule 10 Types, weight and function list of raw materials of covered electrode coating XI List of tensile strength grades of weld metal Schedule XII List of coating types, current types and welding positions in covered electrode Schedule XIII List of chemical composition and mechanical properties of carbon steel and covered electrode coating Appendix XIV.