Seamless steel tube billet

The billet used in the production of steel pipes is called tube billet. Usually high-quality (or alloy) solid round steel is used as the tube billet. According to different production methods, seamless tubes have billets made of steel ingots, continuous casting billets, forging billets, rolled billets and centrifugally cast hollow billets.Since the quality of the tube billet largely determines the quality of the seamless steel tube, the preparation of the tube billet is particularly important.

In general, the tube blank refers to a round tube billet. The size of the round tube billet is represented by the diameter of the solid round steel. Tube billet preparation includes selection of tube billet model and specification, chemical composition and structure inspection, surface defect inspection and cleaning, cutting, centering, etc.
Production process of seamless steel tube billet is as follows:

Ironmaking – Steelmaking – Open Hearth Steel (or Electric Furnace Steel and Oxygen Blowing Converter Steel) – Ingot – Billeting – Rolled Round Bar – Tube Billet

A) Classification of seamless steel tube billets

The seamless steel tube billet can be classified according to the processing method, chemical composition, forming method, usage conditions, etc. of the steel tube.
For example, according to the treatment method, it can be divided into electric furnace steel pipe billet, converter steel pipe billet and electroslag steel pipe billet; according to the forming method, it can be divided into steel ingot, continuous casting pipe billet, forged pipe billet, rolled pipe billet and centrifugal casting hollow tube. According to the chemical composition, it can be divided into carbon steel pipe billet, alloy steel pipe billet, stainless steel pipe billet and corrosion-resistant alloy pipe billet; Drilling and geological drilling tube billets, fertilizer plant tube billets, bearing tube billets, and other special-purpose tube billets.

B) Selection of seamless steel tube billets

The selection of seamless steel tube billets includes the selection of steel grades, specifications, smelting methods and forming methods.
Select steel grades, processing methods and forming methods according to product standards or order technical conditions. The selection of billet size is based on finding the corresponding billet size in the rolling table according to the size of the steel pipe.

Generally, seamless steel pipe mills use refined converter steel or electric furnace steel for continuous casting of round billets.
When the steel grade or specification cannot be continuously cast, the molten steel or centrifugal casting is made into a hollow round billet. When the size of the tube blank cannot meet the requirements of the compression ratio, a larger size tube blank can be selected and rolled or forged to become a tube blank that meets the size requirements. The calculation formula of the compression ratio is as follows: K=F, 1F where K is the compression ratio; F——the cross-sectional area of the tube blank, mm; F——the cross-sectional area of the steel pipe, mm.

When there are strict requirements on the uniformity of the tube blank composition, inclusion content or gas content, the tube blank smelted by electroslag or vacuum degassing furnace is generally used.