Q345B Structural carbon steel H Beams

Q345bH steel product description

The flange of q345bH is parallel or nearly parallel on the outside and the flange end is at a right Angle, hence the name parallel flange I-steel. The thickness of the web of q345bH is smaller than that of ordinary I-beams with the same height of the web, and the width of the flange is larger than that of ordinary I-beams with the same height of the web, so it is also named wide-rim I-beams. Determined by the shape, the section modulus, moment of inertia and corresponding strength of q345bH steel are significantly better than ordinary I-steel with the same single weight. q345bH steel material is Q345B, Q355B, 16mn, so it is also called q345bH steel, Q355BQ345BH steel, 16MNQ345BH steel.

Q345bH steel specification size

The specification of q345bH steel is expressed by the dimensions of side length and side thickness. At present, the domestic q345bH steel specification is 2-20, the number of centimeters of the side length is the number, and the same q345bH steel often has 2-7 different side thicknesses. Imported q345bH steel indicates the actual size and edge thickness of both sides and indicates the relevant standards. Generally, the side length above 12.5cm is large q345bH steel, the side length between 12.5cm and 5cm is medium q345bH steel, and the side length below 5cm is small q345bH steel.

The order of import and export q345bH steel is generally based on the specifications required in use, and its steel number is the corresponding carbon knot steel steel number. That is, q345bH steel has no specific composition and performance series in addition to the specification number.

The delivery length of q345bH steel is divided into two kinds of fixed size and double size. The selection range of domestic q345bH steel is 3-9m, 4-12m, 4-19m and 6-19m according to the different specifications. The length selection range of Japanese q345bH steel is 6-15m.

The section height of the unequal q345bH steel is calculated according to the long side width of the unequal q345bH steel.

Q345bH steel production process

H-beam steel has two production methods: hot rolling and welding. Welding H-shaped steel is to cut the appropriate thickness of the strip to the appropriate width, and weld the edge and waist together in the continuous welding set. The welding H-shaped steel has the disadvantages of large metal consumption, low economic benefit of production, and difficult to ensure uniform product performance. Therefore, the production of H-shaped steel is mainly based on rolling. The main difference between H-beam and ordinary I-beam in rolling is that the latter can be rolled in a two-roll pass, while the former needs to be rolled in a universal pass. The hot rolled H-shaped steel produced by four-roll universal rolling process with near-final continuous casting billet has the remarkable characteristics of high quality, high efficiency, low consumption and low cost, and has great advantages in improving the quality of iron and steel materials and improving the economic benefit. Hot rolled q345bH steel production process: low alloy billet preparation →Q345B billet heating → rolling → sawing or cutting → Cooling q345bH steel → Straightening q345bH steel →q345bH steel surface cleaning → Bundling q345bH steel → Weighing → Packaging →q345bH steel storage.

Q345bH steel appearance quality requirements

The surface quality of q345bH steel is specified in the standard, and it is generally required that there should be no harmful defects in use, such as delamination, scarring, cracks, etc.

The allowable range of geometrical deviation of q345bH steel is also specified in the standard, generally including bending degree, side width, side thickness, top Angle, theoretical weight and other items, and stipulates that q345bH steel must not have significant torsion.

Q345bH steel chemical composition inspection

(1) Composition index: The chemical composition of q345bH steel belongs to the rolled steel series for general structure, and the main inspection index is C, Mn, P and S. According to the different brand, the content is different, the approximate range is C< 0.22%, Mn: 0.30-0.65%, P< 0.060%, S< 0.060%.

(2) Inspection method: When detecting the above chemical components, the commonly used standard inspection methods are GB223, JISG1211-1215, BS1837, BS manual 19, Ti.