Seamless steel pipe - what are the control steps for quality assurance

Seamless steel pipe - what are the control steps for quality assurance?

Control points of steelmaking process: use high-quality waste iron and steel water to ensure low content of Cu and "five harmful" elements in steel; strengthen dephosphorization and desulfurization, strictly control the target value of chemical composition and smelting temperature as required; ensure sufficient vacuum degree and vacuum treatment time to ensure the degassing effect, and strictly control the superheat of the tundish and the peeling speed during the continuous casting process.

Main points of tube rolling control: strictly control the quality of incoming materials to avoid the uneven head of the steel tube caused by the excessive slope of the end face of the casting billet, and the cracks and external scarring of the steel tube caused by defects such as slag holes on the surface of the casting billet; Strictly control the heating temperature of the annular furnace and the heating furnace, increase the inspection strength of adjusting the hot centering of the tube blank, ensure the centering accuracy of the centering hole of the tube blank, and ensure the wall thickness tolerance and wall thickness unevenness of the steel tube; strengthen the high-pressure water Descale and protect the inner and outer surfaces of the steel pipe to ensure the smoothness of the quality of the inner and outer surfaces of the steel pipe; in order to ensure the outer diameter tolerance and outer diameter roundness, a new type of finished rolling pass is adopted; NDT inspection requires that the sample tube for inspection be inspected every 4 hours. Check once.

Main points of pipe processing control: strictly control the quenching and tempering temperature of the steel pipe, improve the yield strength of the steel pipe, and reduce the internal stress of the steel pipe; control the thermal straightening temperature according to the process requirements, and reduce the residual stress on the surface of the steel pipe; the hydraulic test pressure, pressure stabilization Time; torque, media control, etc.