Cangzhou Junde Steel Pipe Co.,Ltd
Add: South of Qiantong Road, Cangzhou City, Hebei, China
Contact us:Sunny Yang
Seamless Steel Pipe(SMLS Pipe)Quality requirements
① chemical composition of steel: steel chemical composition is one of the most important factors affecting the performance of Seamless Steel Pipe(SMLS Pipe), but also to develop the rolling process parameters and steel pipe heat treatment process parameters of the main basis.
A. Alloying elements: intentionally added, depending on the application
B. Residual elements: steel into, appropriate control
C. Harmful elements: strict control (As, Sn, Sb, Bi, Pb), gas (N, H, O)
Furnace refining or electroslag remelting: to improve the uniformity of chemical composition in steel and steel purity, reduce the non-metallic inclusions in the tube and improve its distribution.
② steel pipe geometry accuracy and shape
A. Pipe diameter accuracy: depends on the fixed (minus) diameter method, equipment operation, process system.
Outside diameter allowable deviation δ = (D-Di) / Di × 100% D: Maximum or minimum outside diameter mm
Di: nominal outside diameter mm
B. Thickness of steel pipe wall thickness: the quality of heating with the tube, the process parameters of the deformation process and adjustment parameters, tool quality and lubrication quality and so on
Wall thickness Allowable deviation: ρ = (S-Si) / Si × 100% S: maximum or minimum wall thickness in cross section
Si: nominal wall thickness mm
C. Steel pipe oval: that does not round the degree of steel.
D. Steel pipe length: normal length, set (times) length, length allowed deviation
E. Steel pipe bending: that the bending of the steel pipe: the length of the steel pipe per degree of bending, the length of the pipe bending
F. Steel pipe end cut slope: that the end of steel and steel pipe cross section of the tilt
G. Steel pipe end groove angle and blunt edge
5. Steel surface quality: surface smooth requirements
A. Hazardous defects: cracks, within the fold, outside the fold, rolling broken, from the layer, scarring, pull concave, convex package and so on.
B. General defects: Ma Hang, green line, scratches, bruises, minor inside, outside the straight, roll and so on.
① due to the surface of the tube defects or internal defects brought about.
② production process, such as rolling process parameters are not correct, the mold surface is not smooth, lubrication conditions are not good, hole design and adjustment is unreasonable.
③ In the process of heating and rolling, heat treatment and straightening, if the heating temperature is improperly controlled, the deformation is not uniform, the heating and cooling speed is unreasonable or the straightening deformation is too large to produce excessive residual stress, May also lead to steel pipe surface cracks.
6. Steel pipe physical and chemical properties: mechanical properties at room temperature, high temperature mechanical properties, low temperature performance, corrosion resistance. The physical and chemical properties of steel pipe mainly depends on the chemical composition of steel, the structure and the purity of steel and steel pipe heat treatment methods.
7. Steel pipe process performance: flattening, flaring, curling, bending, welding and so on.
8. Steel microstructure (macro), high power organization (micro) M, B, P, F, A, S
9. Special requirements for steel pipes: Contract attachments, technical agreements.
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