What welders need to know1

First, master certain welding theory.

Welding theory is derived from practical experience, and the resulting theory guides practical application. Only by closely integrating practical skills with theory can one become a successful welder.

Welding theory is extensive and rich. Many welders have little knowledge of welding when they first start working. Most only learn the basics from veteran welders, mastering only relatively simple techniques and feeling unsure how to solve welding problems.

For example, welding stainless steel with carbon steel rods can result in very poor weld formation. This is because stainless steel has lower thermal conductivity than carbon steel, making it difficult for the molten pool formed by the arc to solidify.

With the advancement of technology and the development of materials, processes, and methods, welders are in urgent need of learning and mastering more theoretical knowledge.

Second, master knowledge of welding materials.

Welding involves contact with many metal materials, each with its own unique characteristics. For example, the mechanical properties of metals include strength, plasticity, hardness, and toughness; and the physical properties of metals include density, melting point, thermal expansion, thermal conductivity, electrical conductivity, and magnetism. All of these issues are closely related to the welding process.

For example, when welding austenitic stainless steel, due to its physical characteristics of high thermal expansion coefficient and large deformation, and poor thermal conductivity, the weld appearance is difficult to control.

Therefore, when welding stainless steel, it is important to use low heat input, low current, short arc welding, and rapid welding. This accelerates cooling, minimizes the time spent in the sensitization temperature zone, and strictly controls the interlayer temperature to prevent intergranular corrosion and reduce weld stress and deformation.

Welding defects can also be avoided by combining theoretical analysis from both macroscopic and microscopic perspectives. For example, weld porosity at construction sites is theoretically categorized as hydrogen porosity, nitrogen porosity, and CO porosity. By analyzing the macroscopic characteristics of these three types of porosity, the weld porosity can be identified and characterized. Combined with the theoretical causes of porosity, the site and welding conditions can be analyzed to identify the cause and overcome it, thereby avoiding porosity.

Many on-site welding phenomena can be addressed through theoretical research and analysis. Furthermore, with the continuous advancement of welding materials, welders must diligently study to become "advanced welders."

3. Learn and Master Welding "Regulations"

Welding "regulations" refer to welding standards and specifications, welder assessment guidelines, and other information. They serve as the basis for implementing welding procedures. Just as individuals must abide by laws and regulations in society, welding procedures for each material are the result of generations of repeated research, experimentation, and exploration. Only products welded according to these procedures can meet service requirements.

Welding procedure standards are a comprehensive set of technical regulations for the welding process. They cover welding methods, pre-welding preparation, welding materials, welding equipment, welding sequence, welding operations, process parameters, and post-weld heat treatment. Different welding methods require different welding procedures.

Welding procedures are determined based on the material, grade, chemical composition, weldment structure, and welding performance requirements of the workpiece being welded. Welders should also strengthen their understanding of relevant welding standards and specifications in addition to their work.

Many relevant welding standards and specifications have been issued at the international, national, industry, and local levels. As a welder, you should regularly review and consult these standards.