1. Suitable welding rods for A105 steel pipe fittings: structural steel welding rods, such as J426, J427 welding rods, etc.

2. A105 is the American ASTM standard number, and A represents ordinary carbon structural steel. Standard name: Carbon steel forgings for pipeline components. Because this standard only specifies one type of carbon steel forging, A105 is also considered a forging carbon steel grade. A105 is also a material code, belonging to special steel, and is a cold forged steel. A105 is a low-carbon steel forging, similar to 20 steel.

3. Ordinary carbon structural steel is also called ordinary carbon steel. The carbon content is 0.06-0.22%, and less than 0.25% is the most commonly used. It belongs to low-carbon steel, and each metal grade indicates the yield point of the steel when the thickness is less than 16mm. Compared with high-quality carbon steel, the restrictions on carbon content, performance range, phosphorus, sulfur, and other residual elements are wider. My country and some other countries divide ordinary carbon steel into three categories based on the delivery guarantee conditions: Class A steel (Class A steel), which only guarantees mechanical properties but not chemical composition; Class B steel (Class B steel), which only guarantees chemical composition but not mechanical properties; and Special steel (Class C steel), which guarantees both chemical composition and mechanical properties. Special steel is often used to manufacture more important structural parts.