What are the main international standards for S235JR steel pipes?
EN 10210 specifies the technical requirements for hot-rolled structural hollow profiles. EN 10219 applies to cold-formed welded structural hollow profiles. EN 10025-2 specifies the chemical composition and mechanical properties of steel. ASTM A53 also includes steel pipes with similar performance requirements to S235JR. In addition, ISO 630 series standards also stipulate the technical conditions for structural steel.
How to detect the chemical composition of S235JR steel pipes?
Spectroscopic analysis can quickly and accurately determine the content of each element, which is particularly suitable for on-site testing. Traditional chemical analysis methods, such as carbon and sulfur analyzers and oxygen, nitrogen and hydrogen analyzers, can provide more accurate results. When sampling, avoid the ends of the steel pipe and select the middle position to avoid segregation. The detection frequency should be carried out according to the furnace batch number, and each batch should be tested at least once. The test results should meet the restriction requirements for harmful elements such as P and S in the EN 10025-2 standard.
What does the mechanical property test of S235JR steel pipe include?
The tensile test determines the yield strength, tensile strength and elongation, and the sample is taken from the transverse direction of the steel pipe. The impact test is carried out at 20°C, using a V-notch specimen, and the impact energy is required to be ≥27J. The bending test evaluates the plastic deformation ability of the material, and the diameter of the bending core is usually 3 times the thickness of the specimen. The hardness test can be carried out using a Brinell or Rockwell hardness tester, and the requirement is not to exceed the specified value. For special purposes, fatigue tests or fracture toughness tests may also be required.
What are the non-destructive testing methods for S235JR steel pipes?
Ultrasonic testing is suitable for detecting internal defects such as inclusions and delamination. Eddy current testing is sensitive to surface and near-surface defects and has a fast detection speed. Magnetic particle testing is used to detect surface cracks, especially in the weld area. Radiography can intuitively display the morphology and size of defects, but the cost is relatively high. Penetrant testing is suitable for surface defect detection of non-ferromagnetic materials.
How to evaluate the dimensional accuracy of S235JR steel pipe?
Use an outside micrometer to measure the outside diameter of the steel pipe, and measure at least three points in the circumferential direction. The wall thickness should be measured with an ultrasonic thickness gauge, and at least one section should be measured per meter along the length. For straightness detection, the steel pipe can be placed on a platform and the maximum gap can be measured with a feeler gauge. The length measurement uses a steel tape measure with an accuracy of ±1mm. For ovality evaluation, the maximum and minimum outside diameters of the same section should be measured and the difference should be calculated.
