EN 10222-4 steel forgings for pressure purposes

1.0571 / P355QH1 Forged Rings, Discs, Flanges and Shafts

EN 1.0571
P355QH1
P355QH
EN 10222-4
+QT condition
Ruling section to 400 mm
KV to −40 °C

Send a drawing, quote in 24 h Jump to the data sheet

Published 18 May 2016. Last updated 3 September 2026. Reviewed against EN 10222-4 by the Jiangyin Jiangnan Metal Co., Ltd. Metallurgical Engineering Team.

1.0571 is the EN material number for P355QH1, a weldable fine-grain carbon-manganese steel for pressure purposes specified in EN 10222-4 and supplied in the quenched and tempered (+QT) condition. It has a tensile strength of 470–630 MPa, a minimum upper yield strength between 275 and 355 MPa depending on ruling section, and guaranteed Charpy V-notch impact energy down to −40 °C. Its defining advantage over the normalized grade P355NH (1.0565) is that the same 355 MPa strength class is held in ruling sections up to 400 mm rather than 100 mm, which is why it is the grade of choice for heavy pressure forgings.

Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging factory at No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China, forging 1.0571 / P355QH1 into seamless rolled rings to 2,500 mm outside diameter, discs and tube sheets to Ø1,800 mm, shafts to 8 m, girth flanges, channel covers, long welding neck nozzles, valve bodies, sleeves, blocks and bars Ø25–500 mm, up to 8,000 kg single-piece weight. Parts are supplied quenched and tempered, ultrasonically tested and certified to EN 10204 3.1 or 3.2. Quotations are returned within 24 hours of receiving a drawing at sales@steelforgepieces.com.

Material number: 1.0571
Steel name: P355QH1also written P355QH
Standard: EN 10222-4forgings, pressure purposes
Condition: +QTquenched & tempered
Ruling section: 400 mmmaximum
Tensile Rm: 470–630MPa
Yield ReH: 275–355MPa, by section
KV at −40 °C: 34 Jlongitudinal, min

What forged products are available in 1.0571 / P355QH1?

Jiangyin Jiangnan Metal produces 1.0571 through three routes, chosen by geometry and order volume. Open-die forging on 25 MN and 40 MN hydraulic presses covers shafts, blocks, hollow bars, heavy discs and tube-sheet blanks. Seamless ring rolling on radial-axial mills produces rings from 200 mm to 2,500 mm outside diameter. That is the usual route for girth flanges, shell courses, exchanger flanges and rolled-ring blanks. Upset forging handles short, large-cross-section discs, hubs and nozzle bodies.

Because 1.0571 is a pressure-retaining grade, the choice of route is not a cost decision alone. A seamless rolled ring gives continuous circumferential grain flow with no weld seam, which is what lets a girth flange or a shell course be signed off without a longitudinal weld to inspect and post-weld heat treat. On heavy tube sheets, near-net-shape forging to the drilled-face contour typically removes 25–40 % of the machining stock.

Seamless rolled rings
Contoured & T-section rings
Girth flanges
Channel covers
Forged discs & tube sheets
Tube plates
Forged shafts
Sleeves, bushes & hollow bars
Cylinders, shells & casings
Valve bodies, bonnets & closures
Valve stems & seat rings
Long welding neck nozzles
FVC self-reinforced nozzles
Nozzle necks & cover flanges
Hubs & housings
Forged blocks
Round / square / flat / hex bars
Shell-and-tube exchanger parts

Seamless rolled ring

OD 200–2,500 mm, height to 600 mm, minimum wall 30 mm. Quenched and tempered after rolling, UT to the agreed acceptance class. Typical use: girth flange and shell-course joint on a pressure vessel.

Forged disc / tube sheet

To Ø1,800 mm and 400 mm ruling section, rough machined with drilling allowance. Transverse impact coupons taken from the prolongation, because the through-thickness direction governs on heavy plates.

Nozzle, shaft & hollow bar

Long welding neck and FVC self-reinforced nozzles, shafts to 8 m, trepanned hollow bars. Weld-prep geometry forged in where the drawing allows, so the fabricator receives a ready bevel.

What is steel 1.0571 (P355QH1)?

1.0571 / P355QH1 is a weldable fine-grain steel of the "P" family (steels for pressure purposes), specified in EN 10222-4, Steel forgings for pressure purposes, Part 4: Weldable fine grain steels with high proof strength. Despite sitting in many suppliers' alloy-steel listings, EN classifies it as a non-alloy quality steel: chromium, molybdenum, nickel and copper are capped as residuals, not added deliberately. Its strength comes from manganese, from a controlled fine grain size, and above all from the quench-and-temper heat treatment.

Reading the designation tells you most of what you need: P for pressure purposes, 355 for the minimum proof strength in MPa at the smallest ruling section, Q for quenched and tempered, H for elevated-temperature properties. Three limits in the composition table do most of the work in service.

The aluminium minimum of 0.020 % is what makes the steel fine-grained. Aluminium ties up nitrogen as aluminium nitride, and the nitride particles pin austenite grain boundaries during heating. That fine grain is why the steel holds 34 J at −40 °C where a plain carbon forging of the same strength cannot.
Sulfur is capped at 0.015 %, which leaves few elongated manganese-sulfide stringers in the forging. Without that ceiling the transverse impact minima would not be achievable at all. On a thick tube sheet or a girth flange it is toughness across the grain flow that governs, not the longitudinal figure.
Carbon stops at 0.20 % and Nb + V at 0.12 %. Both ceilings exist to hold the carbon equivalent down so the steel can be welded on site without elaborate preheat, which is the whole commercial point of a "weldable fine grain" grade.

The steel is not air-hardening and not through-hardening in the tool-steel sense. It is supplied +QT and the certified proof strength belongs to that specific tempering cycle. Anything the fabricator does afterwards at a temperature approaching the tempering temperature will re-temper the part and can push the proof strength below the certified value. A long post-weld heat treatment does it. So does hot forming, or a second stress relief. This is the most common way a compliant 1.0571 forging ends up out of specification, and it is covered in welding, CEV and PWHT below.

1.0571 designations, related grades and cross-references

Engineers reach this steel through several names. Jiangyin Jiangnan Metal Co., Ltd. accepts purchase orders under any of them and cross-certifies on a single mill test certificate.

Table 1. 1.0571 designations and how the grade is written on drawings
System / body	Designation	Notes
EN material number	1.0571	The Werkstoff number. Unambiguous, and the safest thing to put on a purchase order.
EN steel name	P355QH1	Name used in EN 10222-4:1999 and in steel databases for material 1.0571.
EN steel name, later edition	P355QH	The same material number appears as P355QH in EN 10222-4:1998 + A1:2001. Write both names with the number to remove any doubt.
Standard	EN 10222-4	Steel forgings for pressure purposes — Part 4: Weldable fine grain steels with high proof strength.
Delivery condition code	+QT	Quenched and tempered. The N-suffix grades in the same standard are normalized (+N).
Nearest EN flat product	P355QH (1.8867)	EN 10028-6, quenched and tempered plate of the same strength class. Used when a vessel mixes plate and forgings.
Certificate standard	EN 10204 3.1 / 3.2	3.1 issued by our independent quality department; 3.2 countersigned by a third-party inspector.

On "equivalent grades". EN 10222-4 lists no formal equivalents for 1.0571, and the steel databases record none either. Grades used for comparable duties elsewhere, such as ASTM A350 LF2, ASTM A266 Grade 2 and JIS SFVC2B, differ in chemistry, delivery condition and impact requirements. A substitution changes what the certificate is able to state. Treat any cross-reference as a starting point for discussion, never as an authorisation to swap. If your drawing says 1.0571 and your budget says A350 LF2, ask us for both prices and get the end user's written approval before changing the callout.

What is the chemical composition of 1.0571 / P355QH1?

The limits below are the EN 10222-4 requirements for material 1.0571, in weight percent. Every heat we forge is verified twice: ladle analysis from the melt source, then product analysis on the forged part by optical emission spectrometry. Both results appear on the certificate.

Table 2. EN 1.0571 / P355QH1 chemical composition, wt %, per EN 10222-4
Element	Min	Max	Why it is controlled
Carbon (C)	—	0.20	Capped to keep the carbon equivalent low and the steel site-weldable
Silicon (Si)	0.10	0.50	Deoxidiser; contributes modestly to strength
Manganese (Mn)	0.90	1.65	Principal strengthening element; improves hardenability so heavy sections respond to the quench
Phosphorus (P)	—	0.025	Impurity; embrittles grain boundaries
Sulfur (S)	—	0.015	Impurity; low ceiling is what makes the transverse impact minima achievable
Aluminium (Al) total	0.020	0.060	Grain refiner, and the defining addition of a fine-grain steel
Nickel (Ni)	—	0.30	Residual; not a deliberate addition in this grade
Chromium (Cr)	—	0.30	Residual
Molybdenum (Mo)	—	0.08	Residual; distinguishes the grade from Mo-alloyed creep steels such as 16Mo3
Copper (Cu)	—	0.20	Residual; raises CEV and can cause hot shortness during forging
Vanadium (V)	—	0.10	Micro-alloying grain refiner and precipitation strengthener
Niobium (Nb)	—	0.05	Micro-alloying grain refiner
Nitrogen (N)	—	0.020	Controlled so free nitrogen does not cause strain-age embrittlement
Nb + V combined	—	< 0.12	Combined micro-alloy ceiling; too much and weld HAZ toughness falls

Melting route: 1.0571 forging stock is normally produced by electric arc furnace with ladle refining and vacuum degassing. Vacuum degassing is what holds hydrogen low enough to avoid flake cracking in heavy sections, and it is worth specifying explicitly on forgings above about 200 mm ruling section. State the melting route on the enquiry if your specification requires it and it will be reported on the certificate.

Carbon equivalent is not a fixed number. EN 10222-4 sets a maximum CEV that varies with ruling section, and the value delivered depends on where in the composition ranges the heat actually sits. Production heats of 1.0571 typically land in the CEV 0.42–0.48 band. If your welding procedure is qualified to a CEV ceiling, state that ceiling on the purchase order. It has to be agreed before the heat is selected, not discovered on the certificate. Use the CEV calculator below to check a ladle analysis.

What are the mechanical properties of 1.0571?

The values below are the specified minima and ranges for material 1.0571 in the quenched and tempered condition. Tensile properties are verified per EN ISO 6892-1 and impact properties per EN ISO 148-1, on coupons taken from the same heat and the same heat-treatment batch as the forging.

Table 3. EN 1.0571 / P355QH1 room-temperature tensile properties, +QT condition
Property	Value	Comment
Tensile strength, R_m	470–630 MPa	Range, not a minimum. An over-strength forging is as non-compliant as an under-strength one.
Minimum upper yield strength, R_eH	275–355 MPa	355 MPa at the smallest ruling section, falling toward 275 MPa as section increases to 400 mm
Elongation at fracture, A — longitudinal	21–23 % min	Higher minimum on thinner sections
Elongation at fracture, A — transverse	19–21 % min	Applies where transverse test pieces are specified
Maximum ruling section, +QT	400 mm	The thickest cross-section that must reach temperature during heat treatment

Charpy V-notch impact energy

This is where 1.0571 earns its price. The quench-and-temper route plus the fine grain gives guaranteed toughness at temperatures where a normalized carbon steel of the same strength has no specified value at all.

Table 4. EN 1.0571 / P355QH1 minimum Charpy V-notch impact energy, joules, +QT condition
Test-piece direction	+20 °C	0 °C	−20 °C	−40 °C
Longitudinal	63	55	47	34
Transverse and tangential	40	34	27	—

Values are minimum mean of three test pieces at the stated temperature. Proof of the impact values is obtained at the lowest test temperature specified for the grade. Transverse and tangential test pieces have no specified value at −40 °C, which matters: if your design minimum metal temperature is −40 °C and the applicable code requires transverse testing on a heavy section, that combination is outside the grade's specified envelope and must be discussed before order.

Specify the direction as well as the temperature. Most disputes over a 1.0571 certificate are about orientation rather than about the numbers. Longitudinal minima are roughly 55–60 % higher than transverse. On rings and discs above about 150 mm, most pressure codes call for transverse or tangential coupons taken from a prolongation. Write the direction and the coupon location on the drawing, and the certificate cannot be argued with afterwards.

Elevated-temperature proof strength

The "H" in P355QH1 means the grade has specified elevated-temperature properties. EN 10222-4 tabulates minimum 0.2 % proof strength (R_p0,2) at intervals from 50 °C upward, which is what the pressure code uses to set the allowable stress at design temperature. Those values are section-dependent and change between editions of the standard, so rather than reprint a table that may not match the edition in force at your contract date, we supply the applicable figures for your ruling section with the quotation. Send the design temperature with the enquiry and they come back with the price.

Physical properties of 1.0571

1.0571 is a ferritic-pearlitic carbon-manganese steel, so its physical properties are those of plain carbon steel and barely move with the small compositional differences allowed inside the grade. Use these for weight, thermal-expansion and heat-transfer calculations.

Table 5. EN 1.0571 typical physical properties at room temperature
Property	Value	Unit / condition
Density	7.85	g/cm³ (0.284 lb/in³)
Modulus of elasticity	≈ 210	GPa at 20 °C, falling to ≈ 186 GPa at 300 °C
Coefficient of thermal expansion	≈ 12.0	×10⁻⁶/K, 20–100 °C
Thermal conductivity	≈ 48	W/m·K at 20 °C
Specific heat capacity	≈ 470	J/kg·K at 20 °C
Electrical resistivity	≈ 0.20	µΩ·m at 20 °C
Magnetic behaviour	Ferromagnetic	Magnetic-particle inspection is applicable to this grade

Physical properties are typical values for the carbon-manganese steel family, given for design guidance. Where a physical property is contractually significant, thermal expansion in a bolted flange stack-up being the usual case, request that the value be verified for the specific heat before ordering.

Weight check. At 7.85 g/cm³, a 1.0571 ring weight in kilograms is π/4 × (OD² − ID²) × H × 7.85 × 10⁻⁶ with all dimensions in millimetres. The weight calculator below does this for five forging shapes and adds the machining allowance.

1.0571 vs 1.0565, 1.0478 and 1.8936: which grade should you specify?

EN 10222-4 contains six grades in three strength classes, each in a normalized (+N) and a quenched and tempered (+QT) variant. The commercial question is almost always the same: can the cheaper normalized grade carry this section, and at what point does the section force a move to +QT?

Table 6. The EN 10222-4 grade family compared
Property	P355QH1 1.0571	P355NH 1.0565	P285QH 1.0478	P420QH 1.8936
Delivery condition	Quenched & tempered	Normalized	Quenched & tempered	Quenched & tempered
Max ruling section	400 mm	100 mm	400 mm	400 mm
Proof strength class	355 MPa	355 MPa	285 MPa	420 MPa
KV longitudinal at +20 °C	63 J	55 J	63 J	63 J
KV longitudinal at −40 °C	34 J	28 J	34 J	34 J
KV transverse at −20 °C	27 J	not specified	27 J	27 J
Alloying	Non-alloy C-Mn	Non-alloy C-Mn	Non-alloy C-Mn	Ni-alloyed
Relative material cost	≈ 1.15 ×	1 × (baseline)	≈ 1.10 ×	≈ 1.5 ×
Specify it when…	Section exceeds 100 mm, or −40 °C toughness is required, or transverse impacts are called for	Section is under 100 mm and −20 °C longitudinal toughness is enough	355 MPa is more strength than the design needs and weight is not critical	Wall thickness must be reduced and the higher grade's welding controls are acceptable

Cost multipliers are indicative ratios of forged material cost per kilogram against P355NH, based on our own 2026 purchasing, and move with scrap and ferro-alloy indices. Ask for a current spot indication before budgeting. Impact values shown for comparison grades are the specified minima in the same table of EN 10222-4.

The practical decision rule that follows from the table: the section thickness usually chooses the grade, not the designer. Below 100 mm, P355NH is normally the right answer and 1.0571 is over-specification. Above 100 mm the normalized grade is simply not covered, and 1.0571 becomes the default. Between the two, the impact requirement decides. If the design minimum metal temperature is −40 °C, or if transverse coupons are mandated, go to 1.0571 regardless of thickness.

EN 10222-4 grade selector

Enter your ruling section, required proof strength and lowest impact test temperature. The tool returns the grade in EN 10222-4 that covers the combination.

Ruling section, mm Thickest cross-section that must reach temperature

Required minimum proof strength

Lowest impact test temperature

Test-piece direction

Screening only. The applicable pressure code, the design temperature and the fabricator's welding procedure all bear on grade choice. Jiangyin Jiangnan Metal Co., Ltd. supplies material to specification and does not accept design responsibility for grade selection.

How is 1.0571 forged and heat treated?

1.0571 is a straightforward steel to forge and an unforgiving one to heat treat. The forging window is wide; the heat-treatment window is what determines whether the certificate passes.

Table 7. Typical thermal route for a 1.0571 / P355QH1 forging
Stage	Typical parameters	What it controls
Heating for forging	1,150–1,250 °C, soak to through-temperature	Plasticity; too hot and grain coarsens irrecoverably
Forging / ring rolling	Finish above ≈ 850 °C; forging ratio ≥ 3:1	Grain flow, soundness, closure of centreline porosity
Cooling after forging	Still air; slow cool or immediate transfer for heavy sections	Hydrogen diffusion; avoids flake cracking in thick parts
Austenitising	≈ 880–920 °C, ≈ 30 min per 25 mm of ruling section	Dissolves carbides, resets a uniform fine austenite grain
Quenching	Water or polymer, agitated; part in the tank within 60 s of furnace exit	Hardenability response through the section, which is where the 400 mm capability comes from
Tempering	≈ 580–660 °C, held per section, then still-air cool	Sets the final proof strength and the impact energy simultaneously
Testing	Tensile, Charpy, hardness, UT, dimensional	Certification against EN 10222-4

These are the typical production parameters for this grade. The cycle actually applied to your forging is qualified for its ruling section and geometry, recorded on the furnace chart and referenced on the EN 10204 certificate. Heat-treatment parameters are not a substitute for a qualified procedure.

The three things that go wrong

Quench delay on heavy sections. Between 100 mm and 400 mm it is the quench that produces the properties. A part that sits at the furnace door loses the surface-to-core cooling gradient that hardens the interior, and the mid-thickness tensile coupon fails. This is why quench-tank position matters more than furnace uniformity on this grade.
Tempering too low to reach the toughness. Proof strength and impact energy pull in opposite directions across the tempering range. Tempering low gets the strength easily and misses the −40 °C impact value; tempering high gets the toughness and drops below the proof strength minimum. The window that satisfies both narrows as section increases, which is the real reason 400 mm is the limit rather than a hardenability calculation.
Tempering too low to survive the customer's PWHT. This one is covered in the next section. It is the most expensive of the three, because it fails after the forging has already been welded into an assembly.

Welding, carbon equivalent and post-weld heat treatment

Weldability

P355QH1 was designed to be welded. Carbon at 0.20 % max, sulfur at 0.015 % max and a controlled micro-alloy ceiling give it good weldability by SMAW, GTAW, GMAW, FCAW and submerged arc, with matching low-alloy consumables. Preheat requirements follow EN 1011-2, which combines four inputs: carbon equivalent, combined thickness of the joint, hydrogen scale of the consumable, and arc energy. None of those four can be dropped. A low CEV does not license zero preheat on a 300 mm joint.

Table 8. Indicative preheat guidance for 1.0571, per EN 1011-2 principles
CEV (IIW)	Combined thickness	Indicative preheat
≤ 0.45	Under 50 mm	Usually none, with low-hydrogen consumables
≤ 0.45	50–100 mm	≈ 75–100 °C
0.45–0.50	50–150 mm	≈ 100–150 °C
0.45–0.50	Over 150 mm	≈ 150 °C, with interpass control and hydrogen scale B or better
Over 0.50	Any	≈ 150–200 °C; qualify the procedure with a hydrogen-controlled process

Indicative only. Preheat must be established by a qualified welding procedure to EN ISO 15614-1 or the applicable code, using the actual CEV on the certificate, the real joint geometry and the consumable's hydrogen scale. This table is for planning a WPS, not for replacing one.

Post-weld heat treatment, and the rule that catches people out

PWHT temperature must stay below the tempering temperature of the forging, by a margin of at least 20–30 °C. A 1.0571 forging tempered at 600 °C and then given a code PWHT at 620 °C has been re-tempered at a higher temperature than the one it was certified at. Proof strength drops, and the assembly no longer matches the material certificate it was built against.

The fix costs nothing if it is done at enquiry stage and is very expensive afterwards: tell us the PWHT temperature and soak time your fabrication code requires, and we will set the tempering temperature above it. Put it on the purchase order as a line item, not in an email. This single sentence prevents more non-conformances on quenched-and-tempered pressure forgings than any other clause.

Machining and non-destructive examination

1.0571 machines like a normalized medium-carbon steel at 20–28 HRC: no special tooling, carbide inserts at conventional speeds, good chip control. Because the steel is ferromagnetic, the full range of NDE applies. Magnetic-particle inspection per EN ISO 17638 is available on this grade, unlike the austenitic nickel alloys we also forge. Volumetric examination is by ultrasonic testing to EN 10228-3 or ASTM A388 with the acceptance class stated on the order; surface examination by MT or liquid penetrant per EN ISO 3452.

Carbon equivalent (CEV) calculator for 1.0571

Enter a ladle analysis from a mill certificate to get the IIW carbon equivalent and an indicative preheat band. Defaults are a typical production heat of 1.0571.

C, %

Mn, %

Cr, %

Mo, %

V, %

Ni, %

Cu, %

Combined thickness, mm

CEV_IIW = C + Mn/6 + (Cr + Mo + V)/5 + (Ni + Cu)/15. The preheat band is indicative and assumes low-hydrogen consumables. Qualify the procedure to EN ISO 15614-1 before production welding.

Where is 1.0571 used?

1.0571 is a pressure-equipment steel. Almost all of its applications share one characteristic: a heavy section that must stay tough at low temperature and be welded on site.

Pressure vessels and reactors

Girth flanges, shell courses, channel covers, forged heads and nozzle reinforcements on vessels where the wall exceeds what a normalized grade covers. The 400 mm ruling section is the reason the grade appears on heavy-wall reactor drawings.

Shell-and-tube heat exchangers

Tube sheets and tube plates, girth and cover flanges, channel covers, floating-head parts. Transverse toughness is the governing property on a thick tube sheet, and this grade specifies it where the normalized grades do not.

Nozzles and piping components

Long welding neck nozzles, FVC self-reinforced nozzles, nozzle necks, forged tees and reducers, weldolet-type reinforcements. Low CEV keeps site welding practical on large-bore connections.

Valves for pressure service

Valve bodies, bonnets, closures, seat rings and stems where the body must be welded into the line and the service temperature runs below zero, down to the −40 °C limit of the grade.

Where 1.0571 runs out. Below −40 °C the grade is outside its specified impact envelope and a nickel-bearing low-temperature steel should be used instead. Above roughly 400 °C sustained, a molybdenum-alloyed creep-resistant grade such as 16Mo3 or a Cr-Mo steel is the correct choice, because a quenched-and-tempered C-Mn steel will temper in service. And if the design needs proof strength above 355 MPa in a heavy section, move to P420QH (1.8936). Tell us the design conditions in the enquiry and we will confirm which grade meets them. We forge all of them.

Production capability: 1.0571 forging manufacturer

Jiangyin Jiangnan Metal Co., Ltd. has forged open-die parts and seamless rolled rings at Zhouzhuang Town, Jiangyin since 2008, exporting to more than 40 countries. Pressure-grade steels including 1.0571 are run with dedicated quench-tank scheduling, because on this grade the transfer time from furnace to water is a production variable, not a detail.

Max ring OD: 2,500mm
Max disc Ø: 1,800mm
Max shaft length: 8m
Max single piece: 8,000kg
Bar Ø range: 25–500mm
Largest press: 40MN
Typical lead time: 6–9weeks
Quotation: 24 hturnaround

Table 9. Equipment used for 1.0571 / P355QH1 forgings
Operation	Equipment	Capability for 1.0571
Open-die forging, heavy	40 MN free-die hydraulic press	Discs and tube sheets to Ø1,800 mm; shafts to 8 m; single pieces to 8,000 kg
Open-die forging, medium	25 MN free-die hydraulic press	Bars, sleeves, blocks, nozzle bodies; tighter reduction control
Ring rolling	Radial-axial ring mill	OD 200–2,500 mm, height to 600 mm, minimum wall 30 mm
Austenitising & tempering	Bogie-hearth furnaces, ±5 °C uniformity, chart recorded	880–920 °C austenitise; 580–660 °C temper, cycle set to the customer's PWHT
Quenching	Agitated water / polymer tank adjacent to the furnace door	Ruling sections to 400 mm; transfer time logged per batch
Chemistry	Optical emission spectrometer	Full product analysis and CEV, calibrated daily against certified standards
Mechanical testing	Universal testing machine, pendulum impact tester, hardness testers	Tensile per EN ISO 6892-1; Charpy per EN ISO 148-1 to −40 °C; Brinell mapping
NDE	Ultrasonic flaw detection, magnetic-particle bench, penetrant line	UT per EN 10228-3 / ASTM A388; MT per EN ISO 17638; PT per EN ISO 3452
Metallography	Microscope to 1000×	Grain size per EN ISO 643 / ASTM E112; macroetch on request

Machining is performed in-house to rough or finished dimensions, including tube-sheet drilling on request. Where a customer-nominated inspector requires witness points, these are scheduled at heat treatment, mechanical testing and final release.

1.0571 forging weight calculator

Pick a shape, enter finished dimensions in millimetres, and get net weight at the carbon-steel density of 7.85 g/cm³ plus an estimated rough-forging weight. Forgings are priced on input weight, not finished weight, so use the rough figure in your RFQ.

Shape

Machining allowance

Outside diameter, mm

Inside diameter, mm

Height, mm

Quantity, pieces

Net weight uses 7.85 g/cm³. Rough-forging weight is an estimate for budgeting; actual input weight depends on the die profile, upset ratio, test-coupon prolongation and cropping loss, and is confirmed in our quotation. Maximum single-piece capability is 8,000 kg.

What testing and certification is supplied with 1.0571 forgings?

Standard supply for every 1.0571 / P355QH1 forging is an EN 10204 3.1 mill test certificate issued by our own quality department, listing heat number, ladle and product chemistry with CEV, the austenitising and tempering cycle actually used, tensile, impact and hardness results, dimensional report and NDE results. EN 10204 3.2 certificates witnessed by DNV, BV, Lloyd's Register, ABS or TÜV are available on request.

Tests available on request

Charpy V-notch at −20 °C or −40 °C, longitudinal or transverse
Through-thickness tensile on heavy sections
Brinell hardness mapping across the section
Grain size to EN ISO 643 / ASTM E112
Ultrasonic examination to a nominated acceptance class
Magnetic-particle and liquid-penetrant surface examination
Carbon equivalent reported against a contractual ceiling
Simulated post-weld heat treatment on the test coupon

Documentation package

EN 10204 3.1 or 3.2 material test certificate
Heat-treatment chart for the quench and temper batch
UT, MT and PT reports with acceptance criteria stated
Dimensional inspection report against the drawing
Marking record: heat number, grade, drawing number, works number
PED 2014/68/EU material compliance statement where applicable
Packing list, photographs and shipping marks

Simulated PWHT on the test coupon. Where the fabrication code requires post-weld heat treatment, the surest way to prove the forging still meets EN 10222-4 after your PWHT is to subject the test coupon to a simulated PWHT cycle before testing it. Specify the temperature and the total soak time, including any repair-weld reheats you may need, and the certificate then shows properties in the condition the part will actually be in when it enters service, not the condition it left the furnace in.

PED note. For pressure equipment placed on the EU market, PED 2014/68/EU requires the material manufacturer's 3.1 certificate to be supported by an appropriate quality-assurance system, unless the material is covered by a European Approval for Materials. State the PED requirement on the enquiry so the correct certification route is set up before production starts, rather than being discovered at inspection.

Non-conformance handling. Any out-of-specification finding triggers a written report within 24 hours. You receive the finding and the proposed disposition (re-temper, rework, regrade or scrap) before anything is done to the part. No silent rework. Records are retained for ten years so a claim can be traced back to the melt.

How to specify a 1.0571 forging order

An enquiry containing the seven items below can be quoted the same day. Anything missing turns into an email round-trip that costs a day each time.

Table 10. The seven items a 1.0571 enquiry needs
#	Item	What to write
1	Grade wording	EN 1.0571, P355QH1 (P355QH), to EN 10222-4. Writing the number and both names removes any edition ambiguity.
2	Delivery condition	+QT, quenched and tempered. Also give the PWHT temperature and soak time your code requires.
3	Ruling section	The thickest cross-section that must reach temperature. It sets the certifiable proof strength.
4	Impact requirement	Lowest test temperature, test-piece direction, and coupon location on the part.
5	Drawing	2D drawing or 3D model with tolerances, surface finish and datum. State as-forged, rough or finish machined.
6	Testing & certification	UT acceptance class, any CEV ceiling, EN 10204 3.1 or 3.2, inspection body if witnessed, PED if applicable.
7	Commercial	Quantity, required delivery date, Incoterm and destination port.

Drawing callout template

MATERIAL:      EN 1.0571 / P355QH1 (P355QH) to EN 10222-4
CONDITION:     +QT, quenched and tempered
RULING SECT.:  ___ mm
MECHANICAL:    Rm 470-630 MPa; ReH per EN 10222-4 for the ruling section
               A >= 21% longitudinal (19% transverse)
IMPACT:        Charpy V-notch per EN ISO 148-1, ___ degC,
               ___ direction, coupons from prolongation
PWHT:          Customer PWHT ___ degC / ___ h - temper above this temperature
               Simulated PWHT to be applied to test coupon: YES / NO
NDE:           UT per EN 10228-3 class ___ ; MT per EN ISO 17638
               (material is ferromagnetic - MT is applicable)
CHEMISTRY:     CEV(IIW) max ___ to be reported on certificate
CERTIFICATION: EN 10204 3.1 (3.2 with third-party witness if required)
               PED 2014/68/EU material compliance statement: YES / NO
MARKING:       Heat number, grade, drawing number, low-stress stamp

Seven mistakes that cost money on 1.0571 orders

Leaving the PWHT temperature off the order. This is the expensive one. We temper the forging to hit the proof strength, your code PWHT then re-tempers it higher, and the properties fall. Tell us the PWHT cycle before we set the temper and it costs nothing.
Specifying the grade without the ruling section. "P355QH1, ReH 355 MPa min" cannot be ordered on a 300 mm section, because 355 MPa belongs to the smallest sections. Give us the section and the achievable minimum comes back with the quotation.
Saying nothing about impact direction. Longitudinal minima run roughly 55 to 60 % higher than transverse. A certificate showing longitudinal results against a code that wanted transverse ones gets rejected at receiving inspection.
Confusing 1.0571 with 1.0565. Both are 355 MPa grades in the same standard, but 1.0565 is normalized and covered to 100 mm while 1.0571 is quenched and tempered and covered to 400 mm. Order the wrong one for a heavy section and the material cannot be certified.
Reading Rm 470–630 MPa as a minimum. It is a range. Over-strength material fails the specification exactly as under-strength material does, and it is a real risk whenever the temper is set to chase a hardness figure nobody actually specified.
Asking for an impact test below −40 °C. There is no specified value below that temperature, and none at all transverse below −20 °C. If your design minimum metal temperature is lower, you need a different steel rather than a tighter test.
Buying a solid billet for a deep-bored part. On sleeves, hollow shafts and nozzle necks a trepanned or forged-hollow blank usually saves 30 to 50 % of the material weight, plus a large share of the boring time.

Instant RFQ generator: 1.0571 / P355QH1 forgings

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Glossary

Table 11. Terms used on this page
Term	Definition
1.0571	EN material (Werkstoff) number for the steel named P355QH1, a weldable fine-grain steel forging grade for pressure purposes in EN 10222-4. The safest designation to put on a purchase order.
P355QH1 / P355QH	EN steel name for material 1.0571. P = pressure purposes, 355 = minimum proof strength in MPa at the smallest ruling section, Q = quenched and tempered, H = specified elevated-temperature properties.
EN 10222-4	Steel forgings for pressure purposes — Part 4: Weldable fine grain steels with high proof strength. The standard that defines 1.0571.
+QT	Quenched and tempered delivery condition: austenitise, rapid quench, then temper. Produces higher toughness and covers heavier sections than the normalized (+N) condition.
Ruling section	The thickest cross-section that must reach temperature during heat treatment. It sets soak time, quench severity and the proof strength that can be certified. 400 mm for 1.0571.
Fine-grain steel	Steel with a controlled, small austenite grain size, achieved here by an aluminium minimum of 0.020 %. Fine grain raises toughness without raising carbon.
R_eH	Upper yield strength, the stress at which the steel first yields discontinuously. The pressure code's allowable stress is derived from it.
KV	Charpy V-notch impact energy in joules, the measure of resistance to brittle fracture. Quoted per test temperature and per test-piece direction.
CEV (IIW)	Carbon Equivalent Value, C + Mn/6 + (Cr+Mo+V)/5 + (Ni+Cu)/15. An index of hardenability used with EN 1011-2 to set welding preheat. Typically 0.42–0.48 for 1.0571.
PWHT	Post-weld heat treatment. On this grade it must be performed below the forging's tempering temperature, or the certified proof strength is invalidated.
Open-die forging	Hot forging between flat or simple dies that do not enclose the workpiece. Used for shafts, discs, blocks and hollow parts and for sizes beyond closed-die capacity.
Seamless rolled ring	A ring produced by piercing a forged billet and rolling it out on a ring mill, giving continuous circumferential grain flow and no weld seam.
EN 10204 3.1 / 3.2	Inspection document types. 3.1 is issued by the manufacturer's independent quality department; 3.2 is countersigned by a third-party inspector nominated by the purchaser.
PED 2014/68/EU	The European Pressure Equipment Directive. It governs how material certification for pressure-retaining parts must be substantiated for equipment placed on the EU market.

Frequently asked questions: 1.0571 / P355QH1

What is steel 1.0571?

1.0571 is the EN material number for P355QH1, a weldable fine-grain carbon-manganese steel for pressure purposes specified in EN 10222-4, Steel forgings for pressure purposes — Part 4: Weldable fine grain steels with high proof strength. It is supplied quenched and tempered (+QT) with a tensile strength of 470–630 MPa, minimum upper yield strength between 275 and 355 MPa depending on ruling section, and guaranteed Charpy V-notch impact energy down to −40 °C. Jiangyin Jiangnan Metal Co., Ltd., an open-die forging factory in Jiangyin, Jiangsu Province, China, forges 1.0571 into seamless rolled rings, discs, tube sheets, flanges, shafts and bars.

What is the difference between 1.0571 (P355QH) and 1.0565 (P355NH)?

Both are 355 MPa proof-strength grades in EN 10222-4 with the same composition family, but they differ in delivery condition and in the section size over which that strength is guaranteed. 1.0565 / P355NH is normalized (+N) and covered to a ruling section of 100 mm. 1.0571 / P355QH1 is quenched and tempered (+QT) and covered to 400 mm. 1.0571 also carries higher guaranteed toughness: 63 J longitudinal at +20 °C falling to 34 J at −40 °C, against 55 J down to 28 J for the normalized grade, and it specifies transverse minima where the normalized grade does not. Choose 1.0571 when the forging is heavy, when toughness must be guaranteed at −40 °C, or when the code calls for transverse impact testing. Full comparison in Table 6.

What is the chemical composition of 1.0571 / P355QH1?

Per EN 10222-4, in weight percent: carbon 0.20 max, silicon 0.10–0.50, manganese 0.90–1.65, nickel 0.30 max, phosphorus 0.025 max, sulfur 0.015 max, chromium 0.30 max, molybdenum 0.08 max, vanadium 0.10 max, nitrogen 0.020 max, niobium 0.05 max, aluminium total 0.020–0.060 and copper 0.20 max, with niobium plus vanadium below 0.12. The aluminium minimum is what makes the steel fine-grained; the low sulfur ceiling is what makes the transverse toughness achievable. See Table 2 for the role of each element.

What are the mechanical properties of 1.0571?

In the quenched and tempered condition, tensile strength is 470–630 MPa, which is a range and not a minimum. Minimum upper yield strength R_eH is between 275 and 355 MPa, decreasing as ruling section increases toward 400 mm. Minimum elongation at fracture is 21–23 % longitudinal and 19–21 % transverse. Minimum Charpy V-notch impact energy is 63 J at +20 °C, 55 J at 0 °C, 47 J at −20 °C and 34 J at −40 °C longitudinal; 40 J at +20 °C, 34 J at 0 °C and 27 J at −20 °C transverse.

Is 1.0571 suitable for low-temperature service?

Yes, down to −40 °C. The grade carries a specified minimum Charpy V-notch impact energy of 34 J longitudinal at that temperature, so the standard itself qualifies it there. Note that transverse and tangential test pieces have no specified value at −40 °C. The lowest specified transverse temperature is −20 °C at 27 J. Below −40 °C the grade is outside its envelope and a nickel-bearing low-temperature steel should be considered instead. State the required test temperature and direction on the enquiry, because on heavy sections most codes call for transverse coupons.

How is 1.0571 forged and heat treated?

Forged from about 1,150–1,250 °C with forging finished above roughly 850 °C, then heat treated: austenitised at approximately 880–920 °C for about 30 minutes per 25 mm of ruling section, quenched in agitated water or polymer, and tempered typically between 580 and 660 °C. The tempering temperature must be set at least 20–30 °C above any post-weld heat treatment the fabricator will later apply, or the PWHT will re-temper the forging and reduce its certified proof strength. The qualified cycle is recorded on the furnace chart and referenced on the EN 10204 certificate. See Table 7.

Is 1.0571 weldable, and does it need preheat?

Yes. P355QH1 was designed as a weldable fine-grain steel, and low carbon plus low sulfur make it readily weldable by SMAW, GTAW, GMAW, FCAW and submerged arc with matching low-alloy consumables. Preheat is decided from the carbon equivalent, the combined thickness of the joint, the hydrogen scale of the consumable and the heat input, following EN 1011-2. Typical CEV for production heats of 1.0571 falls in the 0.42–0.48 band, which usually means no preheat on thin sections and 100–150 °C on heavy ones. Ask for the CEV to be reported on the mill certificate if your welding procedure depends on it, and use the CEV calculator to check a ladle analysis.

Can magnetic-particle inspection be used on 1.0571?

Yes. 1.0571 is a ferritic-pearlitic carbon-manganese steel and is ferromagnetic, so magnetic-particle examination per EN ISO 17638 is fully applicable, unlike the austenitic stainless and nickel alloys we also forge, where MT cannot be used at all. Volumetric examination is by ultrasonic testing to EN 10228-3 or ASTM A388 with the acceptance class stated on the order.

What are the equivalent grades to 1.0571?

EN 10222-4 lists no formal equivalents for 1.0571, and the steel databases record none. The nearest European relation is P355QH (1.8867) in EN 10028-6, the quenched and tempered flat product of the same strength class, used when a vessel mixes plate and forgings. Grades used for comparable duties elsewhere include ASTM A350 LF2 and ASTM A266 Grade 2 carbon steel forgings for pressure service, but their chemistry, delivery condition and impact requirements differ and they are not interchangeable without the end user's written approval.

What is the maximum section thickness for 1.0571?

400 mm ruling section in the quenched and tempered condition, per EN 10222-4. That is four times the 100 mm covered for the normalized grade P355NH (1.0565), and it is the main technical reason 1.0571 is specified for heavy forgings such as thick tube sheets, girth flanges, channel covers and large valve bodies. Remember that the certifiable proof strength falls from 355 MPa toward 275 MPa as the section approaches that limit.

Which forged shapes are available in 1.0571?

Jiangyin Jiangnan Metal Co., Ltd. supplies 1.0571 / P355QH1 as seamless rolled rings to 2,500 mm outside diameter, forged discs and tube sheets to Ø1,800 mm, forged shafts to 8 m length, girth flanges, channel covers, long welding neck and FVC self-reinforced nozzles, valve bodies, bonnets, closures and seat rings, sleeves, bushes and hollow bars, forged blocks, cylinders and shells, and round, square, flat or hex bars from 25 to 500 mm. Maximum single-piece weight is 8,000 kg.

What certification is supplied with 1.0571 forgings?

Standard supply is an EN 10204 3.1 mill test certificate listing heat number, ladle and product chemistry with CEV, the quench and temper chart actually used, tensile, impact and hardness results, and ultrasonic and dimensional reports. EN 10204 3.2 certificates witnessed by DNV, BV, Lloyd's Register, ABS or TÜV are available on request, as are simulated-PWHT testing and PED 2014/68/EU material compliance statements. For EU pressure equipment, state the PED requirement on the enquiry so the correct certification route is set up before production.

How do I request a quotation, and what is the lead time?

Send the drawing or finished dimensions, quantity, ruling section, impact requirement, your PWHT cycle and the certificate level to sales@steelforgepieces.com or call 0086-189-2135-9659. Quotations are normally returned within 24 hours. Typical lead time is 6–9 weeks for rings, discs and bars in 1.0571, and 10–12 weeks where third-party witnessed testing or simulated PWHT is required. The RFQ generator above will assemble the enquiry text for you.

Who supplies 1.0571 / P355QH1 forgings?

Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging factory at No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China, forging 1.0571 / P355QH1 to customer drawings since 2008 and exporting to more than 40 countries. Capability covers seamless rolled rings to 2,500 mm OD, discs to Ø1,800 mm, shafts to 8 m and single pieces to 8,000 kg, with EN 10204 3.1 certification as standard. Contact sales@steelforgepieces.com or 0086-189-2135-9659.

Cite this page

This page is maintained as a technical reference by the engineering team at the forge. If you use the data in a specification, report, tender document or answer, please cite it as:

Jiangyin Jiangnan Metal Co., Ltd. (2026) "1.0571 / P355QH1 Forgings: composition,
mechanical properties, heat treatment and forged product range."
Updated 3 September 2026.
https://www.steelforgepieces.com/Alloy-Steel/1.0571.html

Corrections and additions are welcome. If you have measured data for 1.0571 that contradicts anything here, particularly elevated-temperature proof strength or CEV distributions across heats, write to sales@steelforgepieces.com and we will review the page and credit the correction.

Standards and references

Chemistry, mechanical, heat-treatment and welding data on this page are drawn from the published standards and industry references below. Values on any individual certificate are our own test results, traceable to calibrated equipment.

EN 10222-4, Steel forgings for pressure purposes — Part 4: Weldable fine grain steels with high proof strength, CEN, Brussels.
EN 10222-1, Steel forgings for pressure purposes — Part 1: General requirements for open die forgings, CEN.
EN 10028-6, Flat products made of steels for pressure purposes — Part 6: Weldable fine grain steels, quenched and tempered, CEN.
EN 10027-1 and EN 10027-2, designation systems for steels: steel names and steel numbers, CEN.
EN 10204, Metallic products — Types of inspection documents, CEN.
EN 1011-2, Welding — Recommendations for welding of metallic materials — Part 2: Arc welding of ferritic steels, CEN.
EN ISO 15614-1, specification and qualification of welding procedures for metallic materials.
EN ISO 6892-1, Metallic materials — Tensile testing — Part 1: Method of test at room temperature.
EN ISO 148-1, Metallic materials — Charpy pendulum impact test — Part 1: Test method.
EN 10228-3, Non-destructive testing of steel forgings — Part 3: Ultrasonic testing of ferritic or martensitic steel forgings; ASTM A388 for the equivalent ASTM route.
EN ISO 17638 (magnetic particle testing of welds) and EN ISO 3452 (penetrant testing).
EN ISO 643 and ASTM E112, determination of ferritic or austenitic grain size.
Directive 2014/68/EU of the European Parliament and of the Council on the harmonisation of the laws of the Member States relating to the making available on the market of pressure equipment (PED).
ASM Handbook, Volume 1, Properties and Selection: Irons, Steels, and High-Performance Alloys, and Volume 14A, Metalworking: Bulk Forming, ASM International, Materials Park, OH.

Standards are referenced without an edition number because editions change; for procurement, always cite the revision in force at the contract date. Where this page and the standard disagree, the standard governs.

Request a quotation for 1.0571 / P355QH1 forgings

Jiangyin Jiangnan Metal Co., Ltd.

Open-die forging factory producing seamless rolled rings, forged discs, tube sheets, flanges and shafts.
No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China
Tel 0086-189-2135-9659
Email sales@steelforgepieces.com
WhatsApp +86 189 2135 9659

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Send with your enquiry

Drawing or dimensions, and quantity
Grade: EN 1.0571 / P355QH1 to EN 10222-4
Ruling section and required proof strength
Impact test temperature and direction
Your PWHT cycle, if the part will be welded
Certificate level and inspection body if witnessed
Required delivery date, Incoterm and destination

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Forged in the same grades: forging rings, forged disks, forged cylinders, forging steel products and forging pieces.