Seamless steel pipe
1, chemical composition
In order to improve the chemical composition of the steel and the uniformity of the purity of the steel, reduce the non-metallic inclusions in the pipe and improve the distribution status, it is often used to increase the chemical composition of steel, such as tin, lead and lead. ". Equipment, even the use of electroslag furnace furnace remelting refining.
2, dimensional accuracy and shape
The geometry of the seamless steel tube mainly includes the outer diameter, wall thickness, ellipticity, length, curvature, inclination of the tube end face, bevel angle, blunt edge, and section size of the steel tube.
3, surface quality
This standard specifies the requirements for the "smooth surface" of seamless steel tubes. The common defects are: cracks, hairline, infolding, outfolding, roll off, straight, out straight, stratified, boring, pit, convex hull, Ma Hang (MA), spiral path, outer spiral path, green line, Correction concave, roller and so on. Cracks, slight inside and outside straight, slight internal and external spirals, straightening, etc. In addition to internal and external cracks, cracks, broken, rolling, concave, and rolling are general defects.
4, physicochemical properties
Including room temperature mechanical properties at certain temperatures Mechanical properties (high and low temperature properties), corrosion resistance (such as resistance to oxidation, water erosion, and resistance to acids and alkalis, etc.) are normally determined by the chemical composition, properties and steel purity of the steel. Degree and steel heat treatment method. In some cases, the rolling temperature and degree of deformation of the steel tube also affect the performance of the steel tube.
5, process performance
Including flaring, flattening, crimping, bending, and brazing.
Including low-power steel pipes and high-power organizations.
7, special requirements
The user uses standard requirements other than steel.