Continuously cast steel billets · Square (and round) semi-finished sections rolled into bar, rebar, sections and wire rod, specified by section and length, section, rhomboidity, twist, straightness and corner tolerances, steelmaking route, grade family and cast-level chemistry on an EN 10204 certificate
A steel billet is a semi-finished, continuously cast bar of square or round section that a rolling mill reheats and rolls into reinforcing bar, merchant bar, sections or wire rod, or a tube mill pierces into seamless pipe. Ask three things first: which product and grade the billet must roll into, what section, length and tolerances the reheating furnace and mill accept, and which chemistry, traceability and certificates must come with each cast.
Continuously cast carbon and low-alloy steel billets, square and round, for rolling to long products and for seamless tube. Blooms and slabs, ingots, finished bars and rebar, and non-ferrous billets (see high-strength aluminum alloy extrusion billet and forging-grade copper alloy billet) are outside this page.
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British Steel lists square direct-cast billets of 140 × 140 and 180 × 180 mm in lengths from 8,000 to 14,000 mm. Its tolerances are −3/+5 mm on the 140 mm section and −2/+6 mm on the 180 mm section (measured mid-face), diagonal difference (rhomboidity) of at most 10 mm and 14 mm respectively, twist of at most 3° over the length, straightness of 10 mm/m or 100 mm maximum, corner radius of 4 mm, cutting burr of at most 10 mm, and length ±100 mm with up to 5% shorts down to the customer's minimum. Orders are nominally in 280 t multiples, ±10%. [1]
Baku Steel lists square billets from 100 × 100 to 150 × 150 mm (100, 120, 125, 130 and 150 mm) cast on a four-strand radial caster for rebar production, made to GOST 380-2005, and round continuously cast billets of 130, 160, 170, 190 and 220 mm diameter for seamless oil and gas pipe. [2]
Editorial calculation: a 140 mm billet at the tolerance limits measures 137–145 mm, and a 180 mm billet 178–186 mm; 14 m at 10 mm/m would allow 140 mm of bow, so the 100 mm maximum governs on longer billets. [1]
Give the supplier the target product and mill, section and length (with minimum length and shorts allowance), tolerance limits for section, rhomboidity, twist, straightness and corners, grade and chemistry limits, steelmaking route requirements, marking, inspection certificate type, order quantity and delivery terms.
02
British Steel makes its billets by basic oxygen steelmaking with ladle arc furnace refining and vacuum degassing, casts them on an 8-strand caster with sequence casting and full shrouding between ladle and tundish against reoxidation, and states suitability for structural steel to EN 10025 (for example S235, S275, S355) and ASTM (for example A36, A992, A572 grade 50), plain and deformed reinforcing bar, and low-carbon wire rod. [1]
Each billet is hard-stamped with a 5-digit cast number (or paint-stencilled) and can be colour-marked by grade. Inspection certificates to EN 10204 report cast analysis with C, Si and Mn to two decimal places; P, S, total Al, V, Ti, Nb, Sn, Mo, Co, Ca, Cu, Ni, Cr and N to three; and B to four. British Steel lists ISO 9001 and ISO 14001 and ship classification society approvals. [1] Baku Steel says it uses sponge iron and scrap as feedstock. [2]
For high-carbon grades such as tyre-cord and spring wire rod, centre segregation is the critical internal defect. Bi Sheng and co-authors (Special Steel 特殊钢, vol. 43, 2022) cast 150 × 150 mm SWRH82A billets at casting speeds of 1.9–2.3 m/min, secondary-cooling water ratios of 0.75–1.24 L/kg, superheat of 25–28 °C and mould and final electromagnetic stirring of 300–350 A and 300–470 A. At 1.9–2.0 m/min, about 25 °C superheat, 1.01 L/kg water, mould stirring of 350 A at 3 Hz and final stirring of 400 A at 7 Hz, the centre carbon segregation index fell from 1.21 to 1.05. [3]
Editorial calculation: a segregation index of 1.21 on an assumed 0.82% C ladle analysis means about 0.99% C at the centre (0.82 × 1.21), against about 0.86% at 1.05; for wire-drawing grades ask the supplier for its centre segregation index and macro-etch rating, and the casting speed and stirring practice behind them. [3]
03
Chunsheng Li and Brian G. Thomas of the University of Illinois modelled the maximum casting speed of square steel billets (85th Steelmaking Conference, 2002) for a 0.27%C steel, limited by sub-mould bulging that can open off-corner subsurface hot-tear cracks. For a maximum bulging criterion of 4–10 mm, they found critical casting speeds of 5 m/min for a 120 mm square section with an 800 mm mould and 1.5 m/min for a 250 mm square with a 500 mm mould, and concluded that billet casting productivity is limited "to around 1 tonne/min". [4]
The model assumed uniform heat flux around the mould and no sub-mould support, and the authors recommend longer moulds and properly aligned foot rolls for higher productivity [4]. British Steel casts 140 × 140 and 180 × 180 mm billets on an 8-strand caster [1], and the Illinois study ties the critical speed to section size and mould length. Ask a billet supplier for the casting speed, mould length and foot-roll arrangement used for your section, and for its internal-quality checks, such as the macro-etch and segregation results the SWRH82A study reports [3].
The paper also notes that corner stresses can contribute to transverse corner cracks, though with the ideal taper and alignment assumed they did not limit casting speed [4]. Rhomboidity, which British Steel limits to 10–14 mm diagonal difference, and corner radius [1] are the shape checks to ask for alongside surface crack inspection.
Editorial calculation: at 5.0 m/min a 120 mm square strand casts 0.072 m³ per minute, about 0.56 t/min at a steel density of about 7.8 t/m³ (assumed); at 1.8 m/min a 250 mm square casts about 0.88 t/min, consistent with the paper's limit of around 1 tonne per minute per strand. [4]
| Condition (Li & Thomas, 2002) | Critical casting speed |
|---|---|
| 120 mm square, 800 mm mould | 5.0 m/min |
| 250 mm square, 800 mm mould | 1.8 m/min |
| 250 mm square, 500 mm mould | 1.5 m/min |
| 120 mm square, mould length 600 → 1,100 mm | 3.75 → 6 m/min |
| Sections and moulds studied | 120×120, 175×175, 250×250 mm; 500, 700, 1,000 mm working mould length; 0.75 %/m taper |
Values are from Li and Thomas (2002), text extracted from the PDF on the University of Illinois Continuous Casting Consortium site; it is a modelling study for one steel grade, not a supplier specification.
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No manufacturer record has been reviewed for this product yet. Send your specification and CNFX will match it against manufacturer records.
Ask any supplier for available sections and lengths, tolerance sheet, steelmaking and casting route, grade list and chemistry ranges, internal quality checks (macro-etch, segregation), marking, certificate type, minimum order, packing and delivery terms.
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This is a functional reference built from the sources cited; it is not one maker's specification.
| Requirement | What it controls | Fix in the order |
|---|---|---|
| Section and tolerance | Fit to the mill pass design. [1] [2] | Size; ± mm. |
| Rhomboidity and twist | Feeding and rolling stability. [1] | Diagonal; degrees. |
| Straightness and length | Furnace charging and yield. [1] | mm/m; m. |
| Steelmaking and casting | Cleanliness and chemistry control. [1] | Route. |
| Cast marking and certificate | Traceability and acceptance. [1] | EN 10204; elements. |
06
A billet quotation needs values for your mill. The table explains each field, gives published values where a reviewed source states them, and says what to obtain from the supplier.
| Field | What it means and published values | Ask the supplier for |
|---|---|---|
| Cross-Section Dimensions (mm) | e.g. 100–180 mm square; 130–220 mm round. [2] [1] | Section. |
| Length (m) | e.g. 8–14 m. [1] | Length; shorts. |
| Casting speed (m/min) | Modelled critical speed 5.0 m/min (120 mm) to 1.8 m/min (250 mm) with an 800 mm mould. [4] | Speed and mould length used. |
| Weight (kg) | Not stated in the reviewed sources. | Piece weight. |
| Carbon Content (%) | Reported to two decimals at cast level. [1] | Range. |
| Surface Quality (grade) | Not stated in the reviewed sources. | Defect limits. |
| Centre segregation index | e.g. 1.21 reduced to 1.05 on SWRH82A 150 mm billet. [3] | Index and test method. |
| Tensile Strength (MPa) | Set by the rolled product grade. [1] | Target grade. |
| Yield Strength (MPa) | Set by the rolled product grade. [1] | Target grade. |
| Elongation (%) | Not stated in the reviewed sources. | — |
| Dimensional Tolerance (mm) | e.g. −3/+5 (140) or −2/+6 (180); length ±100. [1] | Tolerances. |
| Straightness (mm/m) | e.g. 10 mm/m, 100 mm max. [1] | Limit. |
| Sulfur Content (%) | Reported to three decimals. [1] | Maximum. |
| Phosphorus Content (%) | Reported to three decimals. [1] | Maximum. |
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Paste it into your enquiry below or into an email to a maker, then replace every bracket.
Product: [rebar; sections; wire rod; seamless tube] Grade: [standard; chemistry limits] Section: [mm; square or round] Length: [m; minimum; shorts] Tolerances: [section; rhomboidity; twist; straightness] Route: [BOS; EAF; degassed] Certificate: [EN 10204 type] Quantity: [t]
No manufacturer record has been reviewed for this product yet. Send your specification and CNFX will match it against manufacturer records.
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British Steel lists 140 and 180 mm square; Baku Steel lists 100–150 mm square and 130–220 mm round. [1] [2]
British Steel gives −3/+5 or −2/+6 mm section, ≤10–14 mm rhomboidity, ≤3° twist and 10 mm/m straightness. [1]
British Steel supplies EN 10204 inspection certificates with cast analysis of listed elements. [1]
A 2022 Special Steel study on 150 × 150 mm SWRH82A billets cut the centre carbon segregation index from 1.21 to 1.05 using 1.9–2.0 m/min, about 25 °C superheat, 1.01 L/kg water and tuned mould and final electromagnetic stirring. [3]
A University of Illinois model (Li and Thomas, 2002) found critical casting speeds of about 5.0 m/min for 120 mm square billets and 1.8 m/min for 250 mm square billets with an 800 mm mould, limited by sub-mould bulging, and productivity limited to around 1 tonne per minute. [4]
Sources checked 2026-10-12. British Steel and Baku Steel Company make continuously cast steel billets.
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