Q: How is the quality of Q235 steel coils inspected in construction projects?
A: ① Dimensional inspection: Verify the length, width, thickness, and bending/punching dimensions; deviations must meet GB/T 3274 requirements.
② Visual inspection: Ensure no warping, cracks, or burrs.
③ Mechanical testing: For batch projects, randomly inspect yield strength and weld strength to ensure compliance with design requirements.
Q: What precautions should be taken when processing and using Q235 steel coils during winter construction?
A: ① When the outdoor welding environment temperature is below -5℃, preheat the welding area (100~150℃) to prevent cold cracking of the weld.
② Avoid rapid cooling after cutting thick coils to prevent internal stress.
③ Protect finished products from rain, snow, and ice formation that could cause rust.
Q: What are the requirements for stacking Q235 steel coils on construction sites?
A: ① Stack on raised platforms (padded with wooden blocks, ≥10cm off the ground) to prevent dampness and rust; ② Stack by category (separate by thickness and specifications), and clearly label; ③ Outdoor stacking requires covering with rainproof tarpaulins, and bare rolls should be protected from prolonged rain.
Q: What quality certification documents are required from suppliers for Q235 steel rolls used in construction projects?
A: A material certificate (quality assurance certificate) must be provided, including grade, specifications, mechanical properties, chemical composition, applicable standards, and production batch number; for bulk purchases, a third-party testing report is required to ensure compliance with national standards.
Q: What are the common quality defects of Q235 steel rolls used in construction, and how to reject them?
A: Common defects include: warping, wavy edges, pitting, scabs, cracks, and thickness deviation exceeding the national standard (within ±0.5mm); if defects affect processing and structural performance (such as cracks and scabs), or dimensional deviations exceed national standards, they can be directly rejected.