1. What does chemical composition analysis refer to?
Chemical analysis method, instrumental analysis method (infrared C-S instrument, direct reading spectrometer, zcP, etc.).
① Infrared C-S instrument: analysis of ferroalloys, steelmaking raw materials, C and S elements in steel.
② Direct reading spectrometer: C, Si, Mn, P, S, Cr, Mo, Ni, Cn, A1, W, V, Ti, B, Nb, As, Sn, Sb, Pb, Bi in block samples
③ N-0 instrument: gas content analysis N, O
2. What are the geometric dimensions and appearance inspections of steel pipes?
① Steel pipe wall thickness inspection: micrometer, ultrasonic thickness gauge, no less than 8 points at both ends and record.
② Steel pipe outer diameter and ovality inspection: caliper, vernier caliper, ring gauge, measure the maximum point and minimum point.
③ Steel pipe length inspection: steel tape measure, manual, automatic length measurement.
④ Inspection of steel pipe curvature: ruler, level ruler (1m), feeler gauge, fine wire to measure curvature per meter and full-length curvature.
⑤ Inspection of steel pipe end bevel angle and blunt edge: angle ruler, pallet.
3. What are the surface quality inspections of steel pipes?
① Manual visual inspection: lighting conditions, standards, experience, markings, steel pipe rotation.
② Nondestructive testing:
a. Ultrasonic flaw detection UT:
It is sensitive to surface and internal crack defects of uniform materials of various materials.
Standard: GB/T 5777-1996 Level: C5
b. Eddy current flaw detection ET: (electromagnetic induction)
It is mainly sensitive to point-shaped (hole-shaped) defects. Standard: GB/T 7735-2004
Level: B
c. Magnetic powder MT and magnetic leakage flaw detection:
Magnetic flaw detection is suitable for the detection of surface and near-surface defects of ferromagnetic materials.
Standard: GB/T 12606-1999 Level: C4
d. Electromagnetic ultrasonic flaw detection:
No coupling medium is required, and it can be applied to high-temperature, high-speed, rough steel pipe surface flaw detection.
e. Penetrant flaw detection:
Fluorescence, coloring, detection of steel pipe surface defects.
4. What are the chemical properties of steel pipes?
① Tensile test: measure stress and deformation, determine the strength (YS, TS) and plasticity index (A, Z) of the material
Longitudinal, transverse specimens, pipe sections, arc-shaped, circular specimens (￠10, ￠12.5)
Small diameter, thin wall, large diameter, thick wall, fixed gauge.
Note: The elongation after fracture of the sample is related to the size of the sample GB/T 1760
② Impact test: CVN, notch C type, V type, work J value J/cm2
Standard sample 10×10×55 (mm) Non-standard sample 5×10×55 (mm)
③ Hardness test: Brinell hardness HB, Rockwell hardness HRC, Vickers hardness HV, etc.
④ Hydraulic test: test pressure, stabilization time, p=2Sδ/D
5. What are the process performance tests for steel pipes?
① Flattening test: round specimen, C-shaped specimen (S/D>0.15) H=(1+2)S/(∝+S/D)
L=40～100mm, unit length deformation coefficient=0.07～0.08
② Ring pull test: L=15mm, no cracks are qualified
③ Flaring and curling test: top center taper is 30°, 40°, 60°
④ Bending test: can replace flattening test (for large diameter pipes)
