Steel plate for hot forming and press forging: choosing the delivery condition that survives reheating
Plate that will be reheated and pressed, bent or forged after delivery · normalised, thermomechanical or quenched-and-tempered, and the temperatures each delivery condition survives
A plate that goes straight into a welded structure is chosen by its strength class. A plate that will be heated again in the customer's furnace and pressed, bent or forged is chosen first by how it got its strength, because the reheat can undo it. Normalised plate takes its properties from a heat near 900 °C and can be formed hot and cooled in air; thermomechanically rolled plate owes its strength to the rolling schedule and softens once it is heated into the austenite range; quenched-and-tempered plate loses its delivered properties above a limit the mill states, 580 °C for one grade. The order has to say which route the plate will see after delivery.
Hot-rolled carbon and low-alloy steel plate bought as feedstock for hot forming, warm (temperature-controlled) forming and press forging after delivery: the choice between normalised (+N, normalised rolled or furnace normalised), thermomechanically rolled (+M) and quenched-and-tempered plate, the forming temperature windows each tolerates, and plate thickness effects on normalising rolling. Structural plate selected by strength class from S355 to about 700 MPa is covered on the High-strength structural steel plate page and ordinary-strength A36, S275 and Q235 plate on the Hot-rolled carbon steel plate page; boiler and pressure-vessel plate on the Pressure vessel quality steel plate page; wear plate on the High-strength abrasion-resistant steel plate page; forging ingots and finished forgings on the High-strength forging steel ingot and Steel forgings pages.
CNFX editorial research · Sources checked October 12, 2026 · 4 sources
How hot each delivery condition may be taken: 980 °C for normalised, 700 °C for thermomechanical, 580 °C for one Q&T grade
A voestalpine patent application on forming hot-rolled steel (US 2010/0187291) sets out the rule for conventional hot forming: forming in the austenite range should not exceed 980 °C if no further annealing follows, must finish above 750 °C, and must be followed by cooling in still air; it says only steels made for normalised annealing can be used, because they keep their strength even after an anneal at 950 °C. [1]
The patent gives commercial-vehicle axle beams as an example of hot-formed parts, where hot forming lowers the forming force and the bending radii and a second step upsets the bend edges for stiffness. It also notes that normalised rolled steels reach at most 460 MPa yield at sheet thicknesses below 16 mm under DIN EN 10025-3, while thermomechanically rolled steels to DIN EN 10149-2 reach a minimum of 700 MPa at 8 mm. [1]
SSAB states that Strenx 100 meets ASTM A514 Grade S and that its workshop guidelines follow those for Strenx 700 E. [4] Editorial calculation: the published ceilings run from 580 °C (Q&T, SSAB) to 700 °C (thermomechanical, voestalpine tests) to 980 °C (normalised, voestalpine), so a part that must be formed in the austenite range, above 750 °C at the finish, can only be made from the normalised plate among these three. [4][1]
Delivery condition
How the plate gets its properties
Published temperature limit after delivery
Normalised annealed (furnace)
Heated to about 900 °C after rolling and air-cooled, giving thick plates a more homogeneous, finer-grained structure than as-rolled [2]
Hot forming up to 980 °C without further annealing, finished above 750 °C, still-air cooling [1]
Normalised rolled (+N by rolling)
Final rolling above the austenite recrystallisation temperature, about 950 °C [1]
Cooling rate after forming governs the properties, as the patent notes for normalised rolled steel [1]
Properties at least equal to the initial values up to 700 °C in the patent's tests; above 700 °C austenite starts to form and the steel softens [1]
Quenched and tempered (SSAB Strenx 100)
Quenching and tempering; minimum yield 690 MPa, 4.762 to 127.0 mm thick [4]
Delivery properties cannot be retained after exposure above 580 °C [4]
Tell the plate supplier the forming route: heating temperature and time, number of forming steps, finishing temperature and cooling, and whether a heat treatment follows. Ask the mill to confirm that the delivered condition keeps its guaranteed properties after that cycle.
02
Normalising-rolled heavy plate above 50 mm: when a later normalising heat lowers the tensile strength
EN 10025-2 lets mills deliver +N plate by normalising rolling instead of an off-line furnace normalise. A 2025 AIST paper by Gerdau, CIT SENAI and CBMM authors explains that this is hard above 50 mm, because the holding thickness for controlled rolling can exceed 100 mm, and that with Nb around 0.040% the non-recrystallisation temperature is about 950 °C, very close to the finishing temperature for +N rolling. [3]
The authors rolled 63 mm and 76 mm plates and tested them before and after a simulated normalising heat treatment, which is what a hot-forming reheat imposes. Before the heat treatment every tensile result met the minimum yield of 325 MPa, tensile strength of 470 MPa and elongation of 18%; after it, four tensile strength results fell below 470 MPa. Plates with a higher yield-to-tensile ratio as rolled showed larger drops in yield and tensile strength after normalising, and the higher-Nb, lower-C design varied less than the standard alloy. [3]
At mid-thickness two individual Charpy values missed the 21 J individual minimum, a position the paper links to lower deformation, less grain refinement and stronger segregation of C, P and S; all standard specimens taken 2 mm below the surface and tested at −20 °C met the 27 J mean and 21 J individual requirements. [3]
For plate over 50 mm that will be reheated, ask whether +N was reached by furnace normalising or by normalising rolling, and ask for tensile and Charpy results after a simulated normalising cycle, including at mid-thickness.
03
Forming at 400–800 °C instead of above 900 °C: scale, press force and thermomechanical plate
The voestalpine application proposes temperature-controlled forming of normalised rolled, normalised annealed or thermomechanically rolled steel heated to 400 to 800 °C, using steel whose structure is stable up to 700 °C, as an alternative to hot forming in the austenite range. [1]
Its argument rests on scale and force. Taking the oxidation rate of iron in air at 600 °C as the reference, the rate is seven times higher at 700 °C and 230 times higher at 950 °C, and at 900 °C scale raised friction in the press. [1] Editorial calculation: between 700 °C and 950 °C the quoted oxidation rate rises by 230 / 7 ≈ 33 times. [1]
Forming at 900 °C halves the pressing force compared with temperature-controlled forming of the same part, but in a two-stage hot process the part cools to about 700 °C and the forces then rise to about 1.5 times. In one hot-forming run the patent examines, the first stage finished at about 790 °C and the second at about 680 °C, below the minimum forming temperature; forming at 700 °C, the part was made in one step with a temperature loss of about 120 °C. [1]
If the press shop forms below the austenite range, specify plate whose properties are guaranteed after heating to the planned temperature, and agree how the blank temperature is measured at the start and end of forming.
04
What to state when ordering plate that will be hot formed
Paste it into your enquiry below or into an email to a maker, then replace every bracket.
Plate: [grade; standard; thickness; width; length]
Delivery condition: [+N furnace normalised / +N normalising rolled / +M / QT]
Forming route: [heating temperature and time; forming steps; finishing temperature; cooling]
After forming: [no heat treatment / normalise / quench and temper]
Tests: [tensile and Charpy after simulated forming cycle; test position incl. mid-thickness]
Parts: [axle beam, dished part, flange, forged blank]
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Compiled and source-reviewed by the CNFX editorial team.
Each manufacturer above links to the page on that company's own website where the product is listed, with the date we checked it. How we source and review
· Page last updated 13 October 2026
Buyer questions
What is the maximum temperature for hot forming normalised steel plate?
A voestalpine patent application gives 980 °C if no further annealing follows, with forming finished above 750 °C and cooling in still air. [1]
Can quenched-and-tempered plate be hot formed?
SSAB states that Strenx 100, a Q&T plate, cannot retain its delivery properties after exposure above 580 °C. [4]
Does thermomechanically rolled plate tolerate reheating?
In voestalpine's tests its properties held at least to the initial values up to 700 °C; above that, austenite formation softened the steel. [1]
Why ask for tests after a simulated normalising cycle on thick +N plate?
In a 2025 AIST paper on 63–76 mm normalising-rolled plate, four tensile strength results fell below the 470 MPa minimum after simulated normalising, although all met it as rolled. [3]
Sources and what still needs a direct check
Sources checked 2026-10-12. Temperature limits come from a voestalpine patent application and plate page and an SSAB product page; the heavy-plate results are from a 2025 AIST conference paper by Gerdau, CIT SENAI and CBMM authors.
