How to choose flux cored wire and solid wire, too full

When submerged arc welding, the flux plays a role in protecting and metallurgical treatment of the weld metal. The welding wire is mainly used as a filler metal, and at the same time, alloying elements are added to the weld and participate in the metallurgical reaction.

How many professionals do you know about welding materials

Description: Z408 is a nickel-iron alloy core, strong reducing graphite coating of cast iron electrode, with high strength, good plasticity, low coefficient of linear expansion. The crack resistance of gray cast iron is similar to that of Z308, but it is stronger than Z308 for nodular cast iron, and it also has good effect on cast iron with high phosphorus content (0.2%P), and the cutting performance is slightly worse than Z308 and Z508. Used for welding of gray cast iron and ductile iron at normal temperature or slightly preheated (to about 200 ℃). AC and DC dual use.

[processing] ultra high strength steel welding matters needing attention

In order to reduce the weight of the structure and improve the bearing capacity, the application of low alloy high strength steel in industrial and mining machinery is paid more and more attention. In recent years, ultra-high strength steel with yield strength> 800MPa has been widely used in domestic construction machinery to meet the needs of large-scale, lightweight and high-efficiency development of construction machinery. Due to the complex alloy system and high hardenability of ultra-high strength steel, cold cracks are easy to occur during welding; in addition, the high strength level of ultra-high strength steel is easy to cause embrittlement of welded joints including welding heat affected zone during welding. Therefore, it is the key to prevent the welding cold crack and ensure the excellent mechanical properties of the welded joint.

Welding material knowledge

When MAG welding, the active gas is only 20%, the alloy element transition coefficient in the welding wire is high, and the impact toughness of the weld is high. The CO2 welding active gas is 100%, the manganese and silicon alloy elements in the welding wire are deoxidized together, the alloy element transition coefficient is slightly lower, and the impact toughness of the weld is not as high as that of MAG welding. For example, Tangshan Shengang MG-51T welding wire (equivalent to ER50-6) has a normal temperature impact toughness value of MAG: 160J;CO2: 110J.

Post-weld heat and post-weld heat treatment

Immediately after welding, all (or part of) the welding parts are heated or insulated to make them cool slowly. The purpose of post-heating is to reduce the content of diffused hydrogen in welded joints, especially in the heat-affected zone, so it is also called dehydrogenation treatment, which is an important technological measure to prevent delayed cracks in welding some low alloy structural steels.

Welding process knowledge

The surrounding conditions during welding include: base material, plate thickness, groove shape, joint form, restraint state, ambient temperature and humidity, cleanliness, and the type and diameter of welding wire (or electrode), welding current, voltage, welding speed, welding sequence, deposition method, gun (or strip) method, etc. determined according to the above factors.