What is the condition of GB5310 seamless steel tube electric arc welding?

For GB5310 seamless steel tube in the arc welding conditions, the fusion zone width of about O. 133 ~ 050mm; of austenitic stainless steel is about 0.06 ~ 0.12mm. Distribution of melt composition of the ancient area of steel for most purposes, the same alloying elements greater than the solubility in the liquid phase solubility in the solid phase. Fusion zone is the junction of solid-liquid two-phase, solute atoms will be opposite from the solid liquid diffusion. Theoretical analysis and experiments proved that the solid - liquid interface on the distribution of solute concentration hut. Elements in the fusion zone (solute) concentration determined by the distribution of elements in the solid - liquid phase partition coefficient and diffusion coefficient. Carbon, sulfur, phosphorus and other elements in the fusion zone of segregation are quite serious. Completely solidified in the fusion zone cooling process, the elements of the diffusion of the opposite will occur, that is, elements from the weld to the base metal migration. The same kinds of welded steel, due to the diffusion of carbon in iron strong, it is time to high temperature homogenization.

The carbon and phosphorus in the combined area changes little baked, so the degree of uneven serious. Solid-liquid surface of the solute concentration distribution of solid - solid - liquid phase coexist, the dotted line - after condensation as the existence of chemical fusion zone heterogeneity, and it leads to physical heterogeneity, therefore, in the organization and performance of the fusion zone are on the uneven, as the weak parts of the welded joint. The formation of polycrystalline heat fusion zone is characterized by melting in a temperature range, this temperature range is the liquidus and solidus vertical distance between. Welding, the base metal on the solid - liquid interface is in between the two isothermal surfaces. Between the two so disheartened at the grain surface, due to anisotropy, the thermal conductivity of the grain direction are different, the results of some melting fast, some slow melting, so the solid - liquid interface to form undulating ellipsoid Therefore, the junction of the base metal and weld is not a line but a zone, called the fusion zone. Grains in the weld fusion zone is in a partially melted when heated state, when cooled to become columnar crystal substrate. The formation of the fusion zone (shadow line that was partially molten fusion zone grain) fusion zone width depends on the material of the solid hut - the temperature range between liquidus, the welded material thermophysical properties and organization of the state.