Principles and basis for selection of Welding Flux
The choice of the principle of choosing electrode electrode welding structure should guarantee under the premise of safe and reliable use, according to the chemical composition of the Welding Flux, mechanical properties, thickness and joint type of the stress of welding structure feature, structure under the condition of using welding performance requirements, welding construction condition and the comprehensive test technology and the economic benefits, such as targeted use of electrodes, if necessary, the welding test.
(A) the same steel Welding Flux selection point
1) the chemical composition of weld metal mechanical properties of ordinary steel, usually require the weld metal and base material, such as strength, Welding Flux tensile strength should be equal to or slightly higher than that of base metal electrode deposited metal. For alloy structural steel, alloy compositions may also require the same or close to the substrate material. In the case of rigid welding structure, high stress joints, and easy to produce cracks when welding, you should consider using low strength than base metal electrode. When the content of carbon, sulfur, phosphorus and other elements of the substrate material is too high, it is easy to produce cracking and anti-cracking weld.
2) Welding Flux consider using performance under dynamic load and impact load of weldment welded components and working conditions, in addition to meet the strength requirement, the main should guarantee the weld metal has higher impact toughness and ductility, choose plastic, high toughness index of low hydrogen type Welding Flux. High temperature, low temperature, wear resistance, or other welding work under special conditions should be used in suitable heat resistant steel, low temperature steel, Welding Flux or other special purpose.
3) welding structure characteristics and stress under the condition of complicated shape structure, rigid heavy welding, the welding process to produce a lot of pressure, welding cracks easily, has good crack resistance, alkaline low hydrogen Welding Flux should be used. It is difficult to clean the welding parts in the rough, and the welding parts should use rust, scale and oil insensitive acid Welding Flux. The welding parts that cannot be turned over should be used for full position welding electrodes.
In case of construction and economic conditions, the welding technology and good acidity shall be adopted in case of the performance requirements of the product. In small or poorly ventilated areas, solder should be used or low dust. Should use the high efficiency of electrode, such as iron powder Welding Flux, high efficiency welding, such as gravity or use in the structure of bottom electrode welding workload, conditions, specific to the type of vertical down welding electrode, in order to improve welding productivity.
(2) selection point of foreign steel welding electrode
Level + 1) Welding Flux different strength low alloy steel (or low-alloy steel + high strength low alloy steel) general requirements not less than two kinds of the minimum degree of weld metal or metal welding joint strength, deposition of the metal electrode selection intensity is able to ensure that the weld metal toughness and ductility and impact strength, the strength of the weld is not lower than base material of the strength of the underside of the joint strength, at the same time should not be higher than the side of the substrate material is poor ductility performance. Therefore, steel wire selection is produced according to the low intensity level. However, in order to prevent welding cracks. Should be a higher level of strength, welding poor steel determination of welding process, including welding specification, preheating temperature and post-weld heat treatment.
2) low alloy austenitic stainless steel + should follow the electrodes, generally used in chromium, nickel content is high, high plasticity, good crack resistance CR25 - Ni13 austenitic steel Welding Flux, the chemical composition of deposited metal value limited choice, to avoid brittle hardened tissue caused by fracture. But the weld deviation should be determined by welding stainless steel and specification.