焊工基础知识(国外英文资料).docVIP

焊工基础知识(国外英文资料) Review of basic knowledge of welding of metal materials Chapter 1: basic knowledge of welding 1. what is welding?. 2. brief classification of welds. 3. steel heat treatment: the steel heating to a certain temperature, insulation for a period of time, and then according to a certain cooling rate cooling to room temperature, this process is called heat treatment. 4. commonly used heat treatment methods are annealing, normalizing, quenching and tempering. Annealing can reduce the hardness of the steel, refine the grain and eliminate the internal stress; normalizing can refine the grain of steel, increase the strength and hardness of the steel; quenching can make the steel get martensite structure, improve the hardness and wear resistance of the steel. 5. mechanical properties of metal material mainly refers to its mechanical properties, is an important indicator of metal materials, mechanical properties of metal materials mainly include tensile properties, bending properties, impact value and hardness. 6. steel is a carbon alloy with a carbon content of less than 2%. When carbon content is greater than 2%, it is called cast steel. When carbon content is less than 0.25%, it is called low carbon steel. When carbon content is 0.25% - 0.6%, it is called medium carbon steel. When carbon content is greater than 0.6%, it is called high carbon steel, which is classified according to carbon content of steel. In addition to the main elements in actual steel iron, also containing carbon. Silicon. Mn. Sulfur. Phosphorus, sulfur in steel. According to the content of phosphorus impurities, and the steel is divided into ordinary carbon steel, high carbon steel, high carbon steel. Steel according to the use of different, can be divided into carbon structural steel, carbon tool steel, special performance steel. 7. carbon structural steel grades representation method, the first letter Q is the yield strength of bend word of the Chinese phonetic alphabet, the lowest, midd