ASME STANDARD WELDED STEEL STRUCTURE BUIDING

The manufacturing process of ASTM A36 welded beams and columns is a comprehensive process involving key stages such as material preparation, assembly, welding, straightening, and inspection. The following is a detailed introduction to the complete production process:

1. Raw material preparation

Steel plate selection: ASTM A36 carbon structural steel plate is selected to meet mechanical performance requirements (such as tensile strength ≥ 400MPa, yield strength ≥ 250MPa) and chemical composition standards (C ≤ 0.26%, Mn ≤ 0.80%).

Cutting and cutting: Flame cutting, plasma cutting, or laser cutting are used to shape steel plates into flanges and web plates. Then clean the cutting edges to remove burrs and oxide layers.

2. Edge chamfering

Process V-shaped or U-shaped groove slopes at the edges of flanges and belly plates to ensure proper welding penetration. This is usually done using a milling machine or planer.

3. Assembly and alignment

H-beam assembly: The assembly machine aligns the web plate and flange into an I-shaped section and fixes them with fixtures. Strictly control the eccentricity of the web plate and the perpendicularity of the end face.

Positioning welding: Temporary spot welding fixes the components in place to prevent deformation during the complete welding process.

4. Main welding processes

Submerged Arc Welding (SAW): Double wire submerged arc welding machine is used for corner welding of T-joints between flanges and belly plates. Welding is carried out in two stages (one side first, then flip the other side), and the parameters are adjusted according to the thickness of the sheet metal.

Gas Metal Arc Welding (GMAW): Used for thin plates or local repairs, typically using CO ₂/MAG shielding gas.

Preheating control: If the thickness of the board exceeds the specification (e.g. ≥ 25mm), it needs to be preheated to 100-150 ° C to minimize the risk of cold cracking.

5. Post weld treatment

Weld cleaning: Remove slag and spatter, and visually inspect defects such as undercutting and porosity.

Stress relief: If necessary, perform annealing (heating to 600-650 ° C and then slowly cooling) to reduce residual welding stress.

6. Straightening and plastic surgery

Mechanical straightening: Roll straightening machine or hydraulic press corrects flange angle deformation or web plate buckling, ensuring straightness tolerance ≤ L/1000 (maximum 3mm).

Flame straightening: Local heating and water cooling can adjust small deformations.

7. End processing

Sawing or milling the beam/column ends to the final length, ensuring the perpendicularity and flatness of the end faces (tolerance ≤ 1 mm/m) for on-site installation.

8. Quality inspection

Non destructive testing (NDT): Ultrasonic (UT) or radiographic (RT) testing of major welds in accordance with AWS D1.1 standard.

Dimensional inspection: Use calipers or laser measuring tools to verify key dimensions (section height, width, web thickness).

Mechanical testing: Samples undergo tensile, bending, and impact testing to verify material and weld performance.

9. Surface treatment and coating

Sandblasting: Achieve Sa2.5 level cleanliness and enhance coating adhesion.

Anti corrosion coating: Apply primer (such as zinc rich epoxy resin) and topcoat, with a dry film thickness of ≥ 80 μ m.

Steel construction project

Standard Certificate

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