Application of new technology in steel structure welding 1 Welding method In the steel structure industry, electrode arc welding was introduced in the 1940s. Submerged arc welding technology was introduced from the former Soviet Union in the mid-1950s. After the 1970s, due to the extensive use of box-shaped members of steel structures and medium-thick plates, they were successively tested and successfully applied. Core welding wire and flux cored wire CO 2 gas shielded welding, submerged arc double wire welding, submerged arc three wire welding, melting nozzle electroslag welding, bolt welding and other welding techniques. The application of CO 2 gas shielded welding in building steel structures has greatly improved the welding production efficiency and shortened the construction period, and has gradually replaced manual arc welding. CO 2 gas shielded welding can be divided into solid wire (GMAW) and flux cored wire (FCAW) according to the wire. Solid wire CO 2 or mixed gas shielded welding, in the production of steel structure, according to the thickness of the plate and the crack, crack sensitivity, select the corresponding sprayed liquid, pulsed current through the liquid, the German solid wire CO 2 Gas shielded welding, flux cored wire CO 2 gas shielded welding, compared with the equal diameter solid wire, the metal boundary area of ​​the wire becomes smaller, the current density increases at the same current level, and the welding efficiency of the wire is close to the solid core CO 2 welding. In the same size fillet weld, the overall efficiency and economic benefits are even better than solid CO2 welding due to the small splash, easy cleaning and concave forming of the weld. In particular, the British indicated that the CO 2 gas shielded welding has a very low hydrogen content due to the oxidizing property of the arc atmosphere and has a good hydrogen crack resistance. The self-shielded flux-cored wire is also used in the construction steel structure. It is more convenient to use because it does not require gas protection. However, due to the high diffusion hydrogen content of the self-shielded flux-cored wire, it is currently only used for steel with a small tendency to cold crack. The welding or non-essential parts of the welding, the problems to be solved in the future, one is the improvement of the resistance to cold cracking, and the second is the reduction of material costs. 2 Welding equipment The welding equipment used in construction steel structure mainly includes manual welding machine, MIG and MAG welding machine, submerged arc welding machine, electroslag welding machine, etc. With the development of power electronics technology and microelectronic technology, the welding machine is moving towards high quality and high efficiency. The development of energy saving and controllability is stronger, and the welding machine is smaller in size, lighter in weight and more suitable for on-site operation. Especially the popularization of inverter power supply has greatly promoted the development of steel structure welding equipment. The weight of the inverter power welding machine is only 1/5 to 1/10 of the weight of the traditional arc welding power source, and the volume is reduced to the traditional arc welding. One-third of the power supply, the external characteristics of the power supply can be controlled. If the inverter welder is controlled by a microprocessor, simply change the software or change the operating function indication of the panel. Various welding methods can be realized, such as MAG, TIG, MIG, PuiseMIG, etc. At present, a new control technology, namely double zero-switching resonant circuit, is used on the inverter welding machine, which is more environmentally friendly, energy-saving and efficient. protruding. Looking at the welding equipment used in the domestic steel structure industry, there are mainly the following characteristics and trends: 1 extensive use of advanced technology, the welder function is more perfect; 2 further improvement in mechanization, automation and complete sets; 3 Electronic computers and welding robots are also beginning to be used in the production of steel structures. 4 There are many factors in factory production and on-site installation. There are many cross-operations in different types of work, and it is difficult to install on site. Previous Next Brinell hardness tester is a precision measuring instrument for measuring brinell hardness of metals . Brinell Hardness Tester,Portable Brinell Hardness Tester,Brinell Hardness Test Unit,Portable Hardness Tester Brinell TROJAN (Suzhou) Technology Co., Ltd. , https://www.trojanmaterial.com
3 There are many varieties of steel products, and more and more tend to use low-alloy high-strength structural steel and large-thickness steel. With the continuous improvement of steel production technology, cast steel, austenitic stainless steel and composite steel plate are also getting more and more. The more applications. Therefore, before on-site construction, in accordance with the delivery status of the steel used, it is necessary to conduct the weldability test of the new steel in real time, explore the scientific welding process parameters, and formulate the corresponding welding process measures.
Brinell hardness tester is mainly used for cast iron, steel, non-ferrous metals and the degree of hardness measurement of the soft material such as alloy, brinell hardness test is one of the largest dimple all Hardness Testing method, it can reflect the comprehensive performance of materials, from the sample organization microsegregation and composition is not uniform, so it is a kind of hardness test method with higher accuracy.