Cold Rolled Steel

Common Defects and Causes? Surface Cracks: Improper continuous casting/rolling process, enrichment of residual elements (Cu) Welding Cracks: Insuffici

Which industries are suitable? Construction: Factories, stadiums, high-rise steel structures Bridges: Highway/railway bridges (Q345q series) Machinery

Commonly Used Welding Materials? Manual Welding: E5015 (J507), E5016 (J506) Submerged Arc Welding: H08MnA + HJ431 Gas Shielded Welding: ER50-6 Welding

Common delivery conditions? Hot-rolled (AR): Low cost, suitable for ≤16mm, room temperature and low pressure. Normalized (N): Uniform grains, good

Mechanical properties (t≤16mm)? Yield strength **≥345MPa**; Tensile strength 470–630MPa; Elongation **≥21%**; Passes 180° cold bend

What is Q345 steel? Low-alloy high-strength structural steel, formerly GB/T 1591-2008, now replaced by Q355 (GB/T 1591-2018). 2. What does "Q345&

Can it be galvanized? Hot-dip galvanized, with good adhesion and improved corrosion resistance, suitable for outdoor/marine environments. Common defec

Flaw detection requirements? Important structures: UT (ultrasonic) Class I; Pressure vessels: UT+MT/PT. Relationship with 16Mn? Q345 = old 16Mn (old g

Common Specifications? Steel Plates: 6–100mm; Section Steel: H-beams, I-beams, channel steel; Steel Pipes: Seamless/Welded pipes. Design Strengt

Difficulty of gas cutting/drilling? Easy to cut and drill, moderate hardness (HB≈150–180), no tendency to harden. Cold bending performance

What is Q345R? It's a pressure vessel steel, with the same strength grade but lower S/P (Salt/Potential), stricter impact resistance, and higher f

Tensile strength range? 470–630 MPa (all thicknesses). Elongation after fracture? ≥21% (A5). Main chemical composition (wt%)? C≤0.20; Si&l