How much do you know about the quality of hot-rolled seamless steel pipe?

　　Benefits: It can destroy the casting structure of steel ingots, refine the grains of steel, and eliminate the shortcomings of microstructures, thereby making the steel structure dense and improving mechanical properties. This improvement is mainly reflected in the rolling direction, so steel is no longer isotropic to a certain extent. Bubbles, cracks and looseness formed during the casting process can also be welded under high temperature pressure.

　　Disadvantages: After hot rolling, non-metallic inclusions in the steel are pressed into thin slices, and delamination (sandwich) occurs. Delamination greatly reduces the effect of pulling the steel in the thickness direction, and delamination may occur when welding is shortened. Welding shortens the bow | strain, and the part strain usually reaches several times the yield point strain.

　　The residual stress caused by uneven cooling is much larger than the strain caused by load. Residual stress is an internal self-phase equilibrium stress without external forces. Each section of hot rolled steel has such residual stress. The larger the standard in general steel, the greater the residual stress. Although the residual stress is self-phase balanced, it still has a certain effect on the function of steel members under the action of external forces. Aspects such as deformation, stability, fatigue resistance, etc. may be unfortunate.

　　Hot rolled steel products with poorly controlled thickness and side width. We are familiar with thermal expansion and contraction. Due to the pre-shared hot rolling, even if the length and thickness meet the requirements, there will be a certain negative difference after cooling. The wider the width of the negative difference, the thicker the thickness, the more obvious the performance. Therefore, for large steel, the side width, thickness, length, angle and edge of the steel cannot be too accurate.