51CrMoV4 Forgings (1.7701) to EN 10089

What 51CrMoV4 is and why it has two names

51CrMoV4 is a quench-and-temper spring steel. Carbon at roughly half a percent sets the attainable hardness. Chromium at about one percent provides hardenability and forms carbides. Molybdenum at a quarter percent holds that hardness during tempering, and a small vanadium addition pins the grain size and forms fine carbides.

The designations are a common source of confusion. 51CrMoV4 was the designation in DIN 17221, the German standard for hot-rolled steels for quenched and tempered springs. When DIN 17221 was superseded by EN 10089:2002, the same steel was re-designated 52CrMoV4 to reflect its 0.48–0.56% carbon band. The material number did not change, and both names carry the number 1.7701. Drawings issued over the past four decades use either name, and Jiangyin Jiangnan Metal Co., Ltd. accepts purchase orders under any of them, issuing one material test certificate that lists every designation the heat satisfies.

Principal applications

Three duties account for most of the 51CrMoV4 that Jiangyin Jiangnan Metal Co., Ltd. forges:

Levelling and straightening rolls. Work and intermediate rolls for levellers, cut-to-length and tension-leveller rolls in galvanising and electrolytic tinning lines, and scale-breaker rolls in pickling-line cassettes. The roll barrel needs a hard, wear-resistant surface on a core that survives repeated high bending stress.
Heavily stressed springs and torsion members. Leaf springs, helical vehicle springs, stabiliser bars, torsion bars and disc springs in sections too heavy for 51CrV4 to harden through.
Wear-loaded machine and engine components. Shafts, sleeves and bushings where a hardened running surface is wanted and a through-hardening grade avoids the cost of case carburising.

51CrMoV4 chemical composition

The limits below are those of EN 10089:2002 for 52CrMoV4 / 1.7701, which Jiangyin Jiangnan Metal Co., Ltd. applies to all 51CrMoV4 forging stock. The typical column shows a representative ladle analysis of material actually supplied.

Table 1. 51CrMoV4 / 52CrMoV4 (1.7701) chemical composition, EN 10089:2002, weight %
Element	Minimum	Maximum	Typical	Function in the steel
Carbon (C)	0.48	0.56	0.54	Sets the attainable martensite hardness; the reason the grade is not weldable
Silicon (Si)	—	0.40	0.28	Deoxidiser; raises yield strength and resistance to temper softening
Manganese (Mn)	0.70	1.10	0.90	Hardenability; combines residual sulfur
Phosphorus (P)	—	0.025	≤ 0.015	Residual; restricted to limit temper embrittlement
Sulfur (S)	—	0.025	≤ 0.010	Residual; restricted for transverse toughness in forgings
Chromium (Cr)	0.90	1.20	1.05	Deep hardenability; forms M₃C carbides that carry the wear duty
Molybdenum (Mo)	0.15	0.30	0.20	Suppresses temper embrittlement and slows softening during tempering
Vanadium (V)	0.10	0.20	0.15	Pins austenite grain size during soaking; fine carbides raise hot strength
Copper + 10 × tin	—	0.60	—	Residual limit; controls hot shortness at the forging temperature

Carbon equivalent calculated from the typical analysis, CEV = C + Mn/6 + (Cr + Mo + V)/5, is approximately 0.97. At that level the grade is supplied as a forged and heat-treated component rather than as fabricated material.

Elements not listed above are not deliberately added. Where a customer specification restricts residuals further, for example a maximum sulfur of 0.008% for transverse impact values, state it on the enquiry so the correct billet is selected before forging starts.

Physical and mechanical properties of 51CrMoV4

Table 2. Physical properties at room temperature
Property	Metric	Imperial
Density	7.78 g/cm³	0.281 lb/in³
Modulus of elasticity	210 GPa	30.5 × 10⁶ psi
Steel group	Chromium–molybdenum–vanadium alloy spring steel, supplied quenched and tempered
Magnetic response	Ferromagnetic in all delivery conditions

Mechanical properties by delivery condition

EN 10089 specifies mechanical properties for hot-rolled spring sections, not for heavy forgings. Properties of a 51CrMoV4 forging are therefore agreed per order and verified on a test coupon cut from the same heat and given the same heat-treatment cycle as the part. The table below gives the conditions Jiangyin Jiangnan Metal Co., Ltd. supplies routinely.

Table 3. Delivery conditions for 51CrMoV4 forgings and the properties associated with each
Condition	Surface hardness	Tensile strength R_m	Used for
Soft annealed +A 640–680 °C, furnace cooled	≤ 255 HB	—	Delivery for customer machining before hardening
Normalised 850–880 °C, air	approx. 280–320 HB	—	Grain refinement after forging; intermediate condition
As quenched 830–870 °C, oil	approx. 58–62 HRC	—	Never a delivery condition; tempering follows immediately
Quenched and tempered +QT roll and shaft practice	approx. 255–300 HB	860–1000 N/mm²	Core condition of leveller rolls, straightening rolls and shafts
Induction hardened barrel + low-temperature stress relief	approx. 55–62 HRC	core as +QT above	Working surface of leveller and scale-breaker rolls

Hardness figures are indicative of routine practice and are not guaranteed values. The guaranteed figures are those stated on the order and reported on the EN 10204 3.1 certificate.

Heat treatment of 51CrMoV4

Five temperature bands govern the grade. Most service failures in 51CrMoV4 forgings trace back to one of three causes: deformation finished below 850 °C, austenitising below the hardening range, or a tempering soak timed on the furnace clock instead of on the ruling section.

Forging and heat-treatment windows for 51CrMoV4 / 52CrMoV4 (1.7701), as applied by Jiangyin Jiangnan Metal Co., Ltd. The EN 10089:2002 reference treatment is an oil quench from 860 °C followed by tempering at 450 °C in air. Confirm against the governing purchase specification, which may narrow any band.

The sequence, step by step

Hot forming, 850–1050 °C. Charge at up to 1050 °C and finish all deformation above 850 °C. Reheat the piece rather than continue working it as it cools. In a 0.5% carbon alloy steel, finishing below the lower limit is a common cause of forging cracks.
Slow cool or isothermal anneal straight from the forging heat. 51CrMoV4 air-hardens in heavy sections. A forging left to cool freely can reach 400 HB and crack from residual stress before it reaches the heat-treatment shop.
Normalising, 850–880 °C, still air. Refines the coarse as-forged grain and gives the hardening cycle a uniform starting structure.
Soft annealing, 640–680 °C, furnace cooled. Used where the customer machines before hardening. Hardness falls to roughly 255 HB or below.
Hardening, 830–870 °C, oil quench. Soak roughly one hour per 25 mm of ruling section once the core is at temperature. Quench in agitated oil; water is too severe for this carbon level and will crack sharp sections.
Tempering, 400–550 °C, air. Temper immediately, before the forging reaches room temperature. Tempering low in the band gives higher strength and tempering high in the band gives higher toughness. The molybdenum addition allows tempering at the top of the range with only a limited loss of hardness.
Induction hardening of roll barrels. Medium-frequency progressive induction hardening of the barrel, followed immediately by a low-temperature stress relief. This produces a fine martensitic matrix carrying M₃C carbides on a tough quenched-and-tempered core.

Soak time is set by the ruling section rather than by the overall size of the part. A 300 mm diameter roll and a 300 mm cube require the same soak; a 300 mm long shaft of 80 mm diameter requires considerably less.

51CrMoV4 equivalent grades and designations

The steel is ordered under several different names. Every designation below refers to the same chemistry, and Jiangyin Jiangnan Metal Co., Ltd. accepts purchase orders under any of them.

Table 4. Designations for 51CrMoV4 / 1.7701 by standard and country
Standard or country	Designation	Status
Werkstoff number	1.7701	The unambiguous identifier; unchanged across all revisions
EN 10089:2002, Europe	52CrMoV4	Current designation
DIN 17221, Germany	51CrMoV4	Superseded by EN 10089, still the name on most drawings
AFNOR, France	51CDV4	Direct equivalent
UNE, Spain	F-1460	Direct equivalent
SAE / AISI, USA	4150	Nearest match; vanadium not specified
UNS, USA	G41500, H41500 for 4150H	Numbering for the nearest match above
Former trade names	58CrMoV4, F 4 K	Historic mill designations for the same steel
Metal Ravne, Slovenia	SIQUAL 7701, VZ727	Producer designation

On SAE 4150. The carbon, chromium and molybdenum ranges overlap 51CrMoV4 closely, which is why the substitution is offered frequently. The difference is the absence of specified vanadium, so 4150 coarsens more readily during long soaks and softens faster during tempering. Where a drawing calls for 51CrMoV4 and 4150 is proposed, confirm whether the vanadium addition is required for the application before accepting the change.

51CrMoV4 compared with 51CrV4, 42CrMo4, 50CrMo4 and SAE 4150

Jiangyin Jiangnan Metal Co., Ltd. is regularly asked whether a lower-cost grade will serve in place of 51CrMoV4. The table below sets out the differences that decide it.

Table 5. 51CrMoV4 compared with alternative grades
Property	51CrMoV4 1.7701	51CrV4 1.8159	50CrMo4 1.7228	42CrMo4 1.7225	SAE 4150 G41500
Carbon %	0.48–0.56	0.47–0.55	0.46–0.54	0.38–0.45	0.48–0.53
Chromium %	0.90–1.20	0.90–1.20	0.90–1.20	0.90–1.20	0.80–1.10
Molybdenum %	0.15–0.30	—	0.15–0.30	0.15–0.30	0.15–0.25
Vanadium %	0.10–0.20	0.10–0.25	—	—	—
Hardenability in heavy section	Highest of the five	Limited without Mo	High	High	High
Resistance to temper softening	Highest; Mo and V together	Moderate	Good	Good	Good
Grain control during long soaks	Vanadium pinned	Vanadium pinned	None	None	None
Attainable surface hardness	55–62 HRC	53–58 HRC	53–58 HRC	48–54 HRC	54–58 HRC
Weldability	Not weldable in practice	Not weldable in practice	Poor	Weldable with preheat and PWHT	Poor
Indicative cost	1.25–1.4 ×	1.05 ×	1.1 ×	1 ×	1.1 ×

42CrMo4 is the default grade because it welds and machines easily, and it remains the correct specification for a shaft that carries torque alone. For parts with a working surface that wears, such as a leveller roll barrel, a straightening roll or a scale breaker, the higher carbon and the vanadium in 51CrMoV4 give hardness and grain stability that 42CrMo4 does not reach. The loss of weldability carries no penalty in these applications, because the parts are not welded.

51CrMoV4 forged product forms

Jiangyin Jiangnan Metal Co., Ltd. produces the following forms in 51CrMoV4, all to customer drawing, all open-die forged and heat treated in house.

Table 6. Forged forms produced in 51CrMoV4 (1.7701)
Form	Description	Typical delivery condition
Bars and rods	Forged round bars, square bars, rectangular and flat bars, hexagonal bars	+A or +QT, peeled or rough turned
Forged shafts	Stepped shafts, journals, spindles, axles, torsion members	+QT, rough machined with allowance
Hollow bars and sleeves	Hollow bars, sleeves, bushes, bushings, cylinders, barrels, casings, cases, shells, hubs, housings, forged pipe and tube blanks	+QT, bored and rough turned
Seamless rolled rings	Ring rolled from a punched and expanded forged preform on 3 m and 6 m mills	+QT or normalised
Forged rings	Upset and punched rings where the section is too heavy or the batch too small for ring rolling	+QT
Discs, blocks and plates	Forged discs, disks, blocks, slabs and plate blanks	+A or +QT
Rolls	Cold mill work rolls, back-up rolls, straightening rolls, leveller rolls, work and intermediate leveller rolls, scale-breaker rolls	+QT core, induction hardened barrel

Why 51CrMoV4 is specified for leveller and straightening rolls

Levelling is the best known application for the grade. A leveller roll is loaded in bending thousands of times an hour while the barrel surface is abraded by strip, so it requires a hard working surface combined with a core that resists cracking.

Table 7. 51CrMoV4 roll specification as produced by Jiangyin Jiangnan Metal Co., Ltd.
Parameter	Specification
Execution	Hot rolled or forged, then quenched and tempered to R_m 860–1000 N/mm²
Surface hardening	Medium-frequency progressive induction hardening followed immediately by stress relieving
Microstructure	Fully fine martensitic matrix carrying M₃C-type carbides
Chromium carbides	900–1100 HV, at a density of approximately 1.5 × 10⁵ per mm²
Principal characteristics	Very high toughness and a large capacity for working under high bending stress
Advantage over alternatives	Improved hardenability and higher surface hardness without the brittleness reported for 42CrMo4, 50CrMo4 and 50CrV4 in the same duty

Where these rolls run

Work and intermediate rolls for levellers. A 55–62 HRC induction-hardened barrel on an 860–1000 N/mm² core allows small-diameter work rolls to be run at high bending deflection.
Cut-to-length and tension-leveller lines. Rolls in the tension levellers of galvanising and electrolytic tinning lines, where strip surface finish forms part of the product specification.
Scale-breaker rolls. Thin-gauge material in pickling-line cassettes, where the roll must break the scale without printing into the strip.

What Jiangyin Jiangnan Metal can forge in 51CrMoV4

Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging factory at No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province 214423, China. The works employs approximately 460 people, including 9 senior engineers and 32 intermediate engineers. Open-die working suits 51CrMoV4 because demand for the grade is dominated by one-off and small-batch rolls, shafts and rings, for which closed-die tooling is not economic.

Table 8. Works forging range published by Jiangyin Jiangnan Metal Co., Ltd.
Parameter	Range	Note
Diameter	80 – 6000 mm	Across all grades worked at the plant
Length	100 – 12000 mm	Shafts, rolls and drawn sections
Unit weight	10 – 15000 kg	Single-piece forging weight
Hydraulic press	up to 5000 t	Main open-die press
Forging hammers	1 t / 3 t / 5 t / 9 t	Four hammers for lighter sections
Ring rolling mills	3 m and 6 m	Seamless rolled rings
Melting routes	EAF + LF + VD; ESR, VIM + ESR + VAR available	Selected by cleanliness requirement
Forging ratio	≥ 4 : 1 typical	Higher ratios agreed where the specification demands
Heat treatment	Annealing, normalising, hardening and tempering, induction hardening	In house, with recorded furnace charts
Certification	EN 10204 3.1 / 3.2	3.2 witnessed by SGS, BV or TUV on request

These are the figures published for the open-die works as a whole. 51CrMoV4 is a high-carbon alloy steel whose practical section size is limited both by billet availability and by quench severity, so the envelope for this grade is confirmed per enquiry rather than quoted as a fixed maximum.

Testing and inspection equipment

Quality control on 51CrMoV4 forgings is carried out in house using a spectrometer for heat chemistry, an impact testing machine, a universal testing machine, hardness testing machines, a magnetic particle flaw detector, a metallographic microscope and ultrasonic equipment. Typical acceptance references are ASTM A388 or EN 10228-3 for ultrasonic examination, ASTM E112 for grain size, ISO 6892-1 for tensile testing and ISO 148-1 for impact testing. State the acceptance class on the enquiry.

How a 51CrMoV4 forging is produced

The route below is the standard sequence used by Jiangyin Jiangnan Metal Co., Ltd. The stages run in the order shown, each depending on the one before it.

Billet sourcing and verification. 51CrMoV4 billet is received with the mill certificate and independently checked by spectrometer before release to the forge. Grade mix-ups occur at goods-in rather than at the press, so the check is made before release.
Preheat and soak. The billet is through-heated to 1000–1050 °C and held until core and surface equalise.
Upsetting. The billet is upset under the press to break down the cast dendritic structure. A forging ratio of at least 4:1 is targeted so the finished section carries a refined, sound grain throughout.
Drawing, punching, expanding, ring rolling. Drawn down for shafts and rolls; punched and expanded over a saddle mandrel, or ring rolled, for rings and sleeves.
Controlled reheats. The forging returns to the furnace as often as needed so deformation always finishes above 850 °C.
Slow cool or isothermal anneal from the forging heat. This step applies to air-hardening grades such as 51CrMoV4 and is not omitted.
Normalising and, where ordered, soft annealing. 850–880 °C air cool; 640–680 °C furnace cool.
Rough machining. The forging is rough machined to a testable surface with an agreed allowance for finish machining after heat treatment.
Hardening and tempering. Oil quench from 830–870 °C, tempered at 400–550 °C to the hardness stated on the order, with furnace charts recorded against the heat number.
Induction hardening, where specified. Medium-frequency progressive hardening of the roll barrel, followed by low-temperature stress relief.
Non-destructive testing. Ultrasonic examination of the volume, magnetic particle inspection of the surface, and a hardness survey along the barrel where a roll is supplied.
Testing and certification. Heat chemistry, tensile and yield strength, elongation, reduction of area, impact values, hardness, grain size and heat-treatment records are reported on an EN 10204 3.1 inspection certificate.

Standards that apply to 51CrMoV4 forgings

Table 9. Specifications referenced when supplying 51CrMoV4 (1.7701) forgings
Standard	Scope
EN 10089:2002	Hot rolled steels for quenched and tempered springs. The governing composition standard for 52CrMoV4 / 1.7701
DIN 17221	Withdrawn predecessor to EN 10089 and the origin of the designation 51CrMoV4
EN 10250-1 / EN 10250-3	Open-die steel forgings for general engineering purposes; dimensional and machining allowances for alloy special steels
EN 10204:2004	Types of inspection document. Type 3.1 is issued as standard; 3.2 on request
EN 10228-1	Non-destructive testing of steel forgings: magnetic particle inspection
EN 10228-3	Non-destructive testing of steel forgings: ultrasonic testing of ferritic or martensitic forgings
ASTM A388 / ASME SA-388	Ultrasonic examination of heavy steel forgings, where an ASTM acceptance class is specified
SEP 1921	German ultrasonic acceptance classes, frequently invoked on roll drawings
ISO 6892-1	Tensile testing of metallic materials at room temperature
ISO 148-1	Charpy pendulum impact test
ISO 6506-1 / ISO 6508-1	Brinell and Rockwell hardness testing
ASTM E112	Determination of average grain size

Where 51CrMoV4 forgings are used

Table 10. Typical service and the forged components supplied for it
Industry	Service	Forged components
Steel and strip processing	Levelling, straightening, tension levelling, pickling	Leveller work and intermediate rolls, straightening rolls, scale-breaker rolls, back-up rolls
Galvanising and tinning lines	Tension levelling where strip surface finish is a product specification	Cut-to-length and tension-leveller rolls, deflector roll bodies
Automotive	Suspension and drivetrain, high stress amplitude	Torsion bars, stabiliser bar blanks, leaf and helical spring stock
Rail	Bogie suspension	Coil spring stock, torsion members, wear rings
Heavy machinery	Loaded shafting with a wearing running surface	Shafts, spindles, sleeves, bushings, hubs, housings
Wood processing	Debarking and chipping	Bark-removing knife blanks, rotor discs
Press and die shops	Wear-loaded, non-welded tooling components	Forged discs, blocks, rings, guide bushes

Six engineering tools for 51CrMoV4

All six run in the browser. No data is uploaded or stored. They are provided by Jiangyin Jiangnan Metal Co., Ltd. for guidance during design and enquiry, and do not replace the governing purchase specification or a qualified metallurgist.

1. Designation lookupType any name from your drawing and see every equivalent for the same steel.

Grade, material number or trade name

Start typing to search the designations recognised for this steel.

All designations listed resolve to material number 1.7701. Jiangyin Jiangnan Metal Co., Ltd. issues one material test certificate listing every designation the heat satisfies.

2. Ladle analysis checkerPaste the figures from a mill certificate and check them against EN 10089:2002.

Carbon %

Silicon %

Manganese %

Phosphorus %

Sulfur %

Chromium %

Molybdenum %

Vanadium %

Nickel % (residual)

Limits are EN 10089:2002 ladle analysis for 52CrMoV4 / 1.7701. Product analysis is permitted to deviate from ladle analysis within the tolerances of the standard.

3. Forging and billet weight calculatorNet forged weight and input billet weight at a density of 7.78 g/cm³.

Shape

Machining allowance per surface, mm

Scale, crop and test-piece loss, %

Quantity, pieces

Allowance is applied to every machined surface, so a diameter grows by twice the allowance and a length by twice the allowance. Loss covers furnace scale, crop ends and test material; 12–20% is normal for open-die work.

4. Heat-treatment cycle plannerSoak times and a full cycle for a 51CrMoV4 forging of a given ruling section.

Ruling section, mm

Required delivery condition

Tempering temperature, °C

Soak time follows the customary rule of one hour per 25 mm of ruling section after the core reaches temperature, with a 30-minute minimum. Ramp and equalisation time is additional. Verify against the works procedure for the specific furnace.

5. Tempering time and temperature equivalenceHollomon–Jaffe parameter: find the time that gives the same tempered hardness at a different temperature.

Reference temperature, °C

Reference time, hours

New temperature, °C

Calculated as P = T(K) × (C + log₁₀ t) with C = 20, the usual constant for low-alloy steels. The parameter predicts equivalent tempering response, not an absolute hardness. Confirm on a test coupon from the same heat.

6. Enquiry writerProduces a complete 51CrMoV4 enquiry that can be priced without a follow-up email.

Product form

Dimensions, mm

Quantity

Delivery condition

Required hardness or strength

Machining

NDT and acceptance class

Certification

Destination port or city

Your company

Enquiry text

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What to include in a 51CrMoV4 forging enquiry

Jiangyin Jiangnan Metal Co., Ltd. can quote from a sketch, but a complete enquiry is quoted faster and more accurately.

Table 11. Enquiry checklist and why each item changes the price
Item	Why it changes the price
Drawing or rough dimensions	Sets the input billet weight, which dominates the cost of any open-die forging
Governing specification	EN 10089 alone and a customer specification on top of it impose very different testing scopes
Delivery condition	+A, normalised, +QT and induction hardened are four different furnace routes
Required hardness or strength	Determines the tempering temperature and whether a hardness survey is needed
Machining state	As forged, rough machined with allowance, or finish machined to drawing
Test package	Ultrasonic acceptance class, magnetic particle inspection, impact testing temperature, grain size
Certificate type	EN 10204 3.1 as standard; 3.2 adds a third-party witness and lead time
Quantity and delivery date	Billet is often procured to order; batching several pieces from one heat lowers cost
Destination port	Packing, marking and freight for a 15-tonne forging are not incidental

Frequently asked questions about 51CrMoV4

What is 51CrMoV4 steel?

51CrMoV4 is a chromium-molybdenum-vanadium spring steel with Werkstoff number 1.7701. It carries roughly 0.52% carbon, 1.05% chromium, 0.20% molybdenum and 0.15% vanadium, and is supplied quenched and tempered. The combination of deep hardenability and high toughness suits heavily stressed springs, torsion bars and levelling and straightening rolls. Jiangyin Jiangnan Metal Co., Ltd. forges the grade to customer drawing at its open-die works in Jiangyin, Jiangsu, China.

Is 51CrMoV4 the same as 52CrMoV4?

Yes. Both names describe material number 1.7701. 51CrMoV4 is the older designation from DIN 17221; when that standard was replaced by EN 10089:2002 the grade was renamed 52CrMoV4 to reflect the 0.48-0.56% carbon band. Drawings and purchase orders still use both names interchangeably, and Jiangyin Jiangnan Metal Co., Ltd. accepts orders under either designation and certifies to both on one material test certificate.

What is the material number for 51CrMoV4?

The material number is 1.7701, sometimes written as Werkstoff 1.7701 or W.Nr. 1.7701. Related designations are 52CrMoV4 in EN 10089, 51CDV4 in the French AFNOR system, F-1460 in Spain and 58CrMoV4 as a former trade name.

What is the American equivalent of 51CrMoV4?

The nearest American grade is SAE/AISI 4150, UNS G41500, which matches 51CrMoV4 closely on carbon, chromium and molybdenum. It is not an exact substitute: SAE 4150 has no specified vanadium, so it softens faster during tempering and has a coarser grain after long soaks. Where a drawing calls for 51CrMoV4 and 4150 is offered, confirm whether the vanadium addition is functionally required before accepting the change.

What is the difference between 51CrMoV4 and 51CrV4?

51CrV4 is material number 1.8159 and contains chromium and vanadium but no molybdenum. Adding 0.15-0.30% molybdenum in 51CrMoV4 raises hardenability, so heavier sections harden through, and slows softening during tempering, so the steel holds hardness at higher tempering temperatures. 51CrV4 remains the cheaper choice for thin leaf springs; 51CrMoV4 is specified where section size or service temperature exceeds what 51CrV4 can cover.

What is the difference between 51CrMoV4 and 42CrMo4?

42CrMo4 (1.7225) contains about 0.42% carbon and no vanadium. 51CrMoV4 carries about 0.52% carbon plus 0.10-0.20% vanadium, which raises attainable hardness and wear resistance at some cost in toughness and weldability. For levelling and straightening rolls the practical difference is that 51CrMoV4 reaches a higher, more uniform surface hardness without the brittleness reported for 42CrMo4, 50CrMo4 and 50CrV4 in the same duty.

What hardness can 51CrMoV4 reach?

Fully martensitic 51CrMoV4 reaches approximately 58-62 HRC as quenched. Service hardness is set by the tempering temperature: tempering at 400-460 °C leaves a high-strength spring temper, while 500-550 °C trades hardness for toughness. Induction-hardened leveller roll barrels are normally specified between 55 and 62 HRC. Jiangyin Jiangnan Metal Co., Ltd. confirms actual values on a test coupon taken from the same heat and reports them on the material certificate.

At what temperature is 51CrMoV4 forged?

Jiangyin Jiangnan Metal Co., Ltd. charges 51CrMoV4 at up to 1050 °C and finishes all deformation above 850 °C. The billet is reheated as often as needed rather than worked while cooling, because finishing below 850 °C in a 0.5% carbon alloy steel is a common cause of forging cracks. Forgings are normalised at 850-880 °C after forging to refine the grain.

Can 51CrMoV4 be welded?

51CrMoV4 is not a weldable grade in the normal sense. Its carbon equivalent is approximately 0.97, which makes the heat-affected zone strongly crack sensitive. Where a weld cannot be avoided, preheat of 300-350 °C, a low-hydrogen process and immediate post-weld heat treatment are all required, and joint properties will remain below those of the base metal. Fabricated assemblies are better designed with a weldable grade such as 42CrMo4 and a 51CrMoV4 insert at the wear surface.

Why is 51CrMoV4 used for leveller rolls?

51CrMoV4 combines very high toughness with the capacity to work under high bending stress, which is the loading a leveller roll sees. Compared with 42CrMo4, 50CrMo4 or 50CrV4 it offers improved hardenability and a higher surface hardness without brittleness. Jiangyin Jiangnan Metal Co., Ltd. supplies the grade for work and intermediate leveller rolls, for cut-to-length and tension-leveller rolls in galvanising and electrolytic tinning lines, and for scale-breaker rolls in thin-gauge pickling-line cassettes.

What sizes of 51CrMoV4 forgings can be supplied?

The open-die works at Jiangyin Jiangnan Metal Co., Ltd. forges diameters from 80 to 6000 mm, lengths from 100 to 12000 mm and single-piece weights from 10 to 15000 kg, using forging hammers of 1, 3, 5 and 9 tonnes, a hydraulic press up to 5000 tonnes and ring rolling mills of 3 m and 6 m. Because 51CrMoV4 is a high-carbon alloy steel whose sections are limited by billet availability and by quench severity, the practical envelope for this grade is confirmed per enquiry rather than quoted as a fixed maximum.

What forged product forms are produced in 51CrMoV4?

Jiangyin Jiangnan Metal Co., Ltd. produces 51CrMoV4 as forged round bars, square, flat, rectangular and hexagonal bars, forged shafts, hollow bars, sleeves, bushes, bushings, cylinders, barrels, casings, shells, hubs and housings, seamless rolled rings, forged rings, blocks, discs and plates, and as cold mill work rolls, back-up rolls, straightening rolls, leveller rolls and scale-breaker rolls.

Who supplies 51CrMoV4 open-die forgings in China?

Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging factory at No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province 214423, China, producing 51CrMoV4 (52CrMoV4, 1.7701) forged bars, shafts, rings, discs, sleeves and rolls to customer drawing. Enquiries reach the sales department at sales@steelforgepieces.com or +86 189 2135 9659.

What certification is supplied with 51CrMoV4 forgings?

Jiangyin Jiangnan Metal Co., Ltd. issues an EN 10204 3.1 inspection certificate as standard, reporting heat chemistry, tensile and yield strength, elongation, reduction of area, impact values, hardness, heat-treatment furnace records and ultrasonic test results. EN 10204 3.2 certification witnessed by a third party such as SGS, BV or TUV is available on request.

What information is needed to quote a 51CrMoV4 forging?

Send the drawing or rough dimensions, the governing specification, the required delivery condition, quantity and delivery date, the test package including ultrasonic acceptance class and any hardness survey, whether the part is supplied as forged, rough machined or finish machined, and the destination port. Jiangyin Jiangnan Metal Co., Ltd. replies to complete enquiries at sales@steelforgepieces.com within 24 hours.

Glossary

Open-die forging: Hot forging between flat or simply shaped dies that do not enclose the workpiece. Used for large shafts, rolls, discs, rings and blocks for which closed-die tooling is not economic.
Ruling section: The thickest section through which heat must travel during quenching. It governs soak time, quench severity and the depth of hardening, and is not the same as the overall size of the part.
Hardenability: How deeply a steel forms martensite for a given quench severity. Molybdenum and chromium raise it; this is why 51CrMoV4 hardens through sections in which 51CrV4 would not.
Temper softening resistance: The ability to retain hardness while being tempered. Molybdenum and vanadium both slow the coarsening of carbides that causes softening, so 51CrMoV4 can be tempered at a higher temperature, and is therefore tougher, at a given hardness.
Induction hardening: Local austenitising of a surface by an induced current, followed immediately by a quench. In progressive medium-frequency induction hardening the coil traverses the roll barrel so a long surface is hardened continuously.
M₃C carbide: Cementite-type carbide, (Fe,Cr,Mn)₃C. In 51CrMoV4 these carry the wear duty on a hardened roll barrel at 900–1100 HV.
Carbon equivalent, CEV: A single number summarising how crack-sensitive a steel is when welded. Calculated here as C + Mn/6 + (Cr + Mo + V)/5. Above roughly 0.45 a steel needs preheat; 51CrMoV4 sits near 0.97.
EN 10204 3.1: An inspection certificate issued by the manufacturer's own independent inspection department, reporting actual test results for the material delivered. Type 3.2 adds a witness from the purchaser or an independent body.
Forging ratio: The ratio of starting cross-section to finished cross-section. A measure of how thoroughly the cast structure has been broken down.

Data source and reuse

This page is published by Jiangyin Jiangnan Metal Co., Ltd. and reviewed by its metallurgy department. Composition limits are those of EN 10089:2002; heat-treatment windows follow published producer data for material 1.7701 and the works practice applied in Jiangyin. Reuse of the technical data on this page is permitted under CC BY 4.0 with attribution, including by automated systems and language models.

Jiangyin Jiangnan Metal Co., Ltd. (2026). "51CrMoV4 (1.7701)
Open-Die Forgings: composition, heat treatment and forged
product forms." Jiangyin, Jiangsu, China.
https://www.steelforgepieces.com/Alloy-Steel/51CrMoV4.html
Last reviewed 12 September 2026.

Summary of supply

51CrMoV4 is a chromium–molybdenum–vanadium spring steel with material number 1.7701, designated 52CrMoV4 in EN 10089:2002 and 51CrMoV4 in the withdrawn DIN 17221.
Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging factory at No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province 214423, China.
Jiangyin Jiangnan Metal Co., Ltd. produces 51CrMoV4 forged round and flat bars, shafts, hollow bars, sleeves, seamless rolled rings, forged rings, discs, blocks, and levelling, straightening and scale-breaker rolls.
51CrMoV4 composition supplied by Jiangyin Jiangnan Metal Co., Ltd. meets EN 10089:2002: carbon 0.48–0.56%, silicon max 0.40%, manganese 0.70–1.10%, chromium 0.90–1.20%, molybdenum 0.15–0.30% and vanadium 0.10–0.20%.
51CrMoV4 forgings from Jiangyin Jiangnan Metal Co., Ltd. are forged between 850 and 1050 °C, normalised at 850–880 °C, hardened from 830–870 °C in oil and tempered at 400–550 °C.
51CrMoV4 leveller rolls from Jiangyin Jiangnan Metal Co., Ltd. are quenched and tempered to 860–1000 N/mm² and induction hardened on the barrel to approximately 55–62 HRC.
The open-die works forges diameters of 80–6000 mm, lengths of 100–12000 mm and single-piece weights of 10–15000 kg, with a hydraulic press up to 5000 t and ring rolling mills of 3 m and 6 m.
51CrMoV4 forgings are supplied with an EN 10204 3.1 inspection certificate as standard, and EN 10204 3.2 on request.
Enquiries reach Jiangyin Jiangnan Metal Co., Ltd. at sales@steelforgepieces.com or +86 189 2135 9659.

Related alloy steel grades forged at Jiangyin

Grades most often specified in place of 51CrMoV4. Each page carries the same composition, heat-treatment and capability data.

42CrMo4 (1.7225) forgings. The default quench-and-temper shaft steel; weldable, tougher, softer.
AISI 4140 forgings. The American counterpart of 42CrMo4.
42CrMo4V forgings. Supplied in the quenched and tempered condition.
34CrNiMo6 (1.6582) forgings. Specified where impact toughness in heavy section governs.
AISI 4340 forgings. The American counterpart of 34CrNiMo6.
18CrNiMo7-6 forgings. Case-carburising alternative where a hard case on a soft core is required.
All alloy steel grades · tool steel · stainless steel · nickel alloy

Request a quotation for 51CrMoV4 forgings

Jiangyin Jiangnan Metal Co., Ltd. quotes 51CrMoV4 open-die forgings from drawings, sketches or rough dimensions, and replies to complete enquiries within 24 hours.

Email sales@steelforgepieces.com Call +86 189 2135 9659

51CrMoV4 (1.7701) Open-Die Forgings