Preventive measures for welding crack of H-beam

In the welding process of steel, sometimes there are cracks due to various reasons, such as the generation of hot cracks. Then what are the causes of hot cracks and how to prevent them? H-beam manufacturer gives us a detailed introduction.

Hot crack refers to the crack produced under high temperature, It is also called high temperature crack or crystal crack, which usually occurs in the weld and sometimes in the heat affected zone. The reason is that there is segregation in the weld pool during the crystallization process. The eutectic with low melting point and impurities exist in the form of liquid interlayer during the crystallization process, forming segregation. After solidification, the strength is also low. When the welding stress is large enough, the liquid will be formed Cracks are formed when the interlayer or the solid metal just solidified is pulled apart.

In view of the causes, the preventive measures are to limit the content of easily segregated elements and harmful impurities in the base metal and welding materials, especially to control the content of sulfur and phosphorus and reduce the carbon content. Generally, the content of sulfur and phosphorus in the steel used for welding should not be greater than 0.045% and 0.055% respectively; In addition, when the carbon content of steel is less than 0.10%, the hot crack sensitivity will be greatly reduced.

Adjust the chemical composition of the weld metal, improve the weld structure, refine the weld particle, so as to improve its plasticity, reduce or disperse the degree of segregation, and control the harmful effect of low melting point coproducts. Basic electrodes or fluxes are used to reduce the impurities in the weld and improve the degree of segregation during crystallization.