What 1.7701 steel is
1.7701 belongs to the EN 10089:2002 group of hot-rolled steels for quenched and tempered springs. It carries roughly 0.5% carbon, about 1% chromium, 0.2% molybdenum and a vanadium addition of 0.10 to 0.20%.
Molybdenum raises hardenability and suppresses temper embrittlement, so heavier sections harden through more reliably than in a plain chromium spring steel. Vanadium forms fine carbides that hold grain size down during austenitising, which lifts fatigue strength and resistance to relaxation under load. Those two properties are the reason the grade turns up in torsion bars, heavily loaded springs and forged parts that have to hold a preload under cyclic stress at working temperature.
The same chemistry affects how the steel behaves in a forge shop. It is air-hardening enough that sections have to be cooled slowly after forging and annealed before machining. Skip that step and hard martensitic zones make finishing slow and expensive. We run every 1.7701 forging through a controlled post-forge cool and an annealing cycle.
Chemical composition of 1.7701 / 52CrMoV4
| C | Si | Mn | P | S | Cr | Mo | V |
|---|---|---|---|---|---|---|---|
| 0.48-0.56 | max 0.40 | 0.70-1.10 | max 0.025 | max 0.025 | 0.90-1.20 | 0.15-0.30 | 0.10-0.20 |
Residuals are limited by Cu + 10 Sn < 0.60%. Balance iron.
| C | Si | Mn | Cr | Mo | Ni | V | W |
|---|---|---|---|---|---|---|---|
| 0.54 | 0.28 | 0.90 | 1.05 | 0.20 | - | 0.20 | - |
The heat analysis for your own order is printed on the EN 10204 3.1 certificate that ships with the forging.
Mechanical and physical properties
| Property | Metric | Imperial |
|---|---|---|
| 0.2% proof stress, Rp0.2 | 1180 N/mm² | 171 ksi |
| Tensile strength, Rm | 1370-1670 N/mm² | 199-242 ksi |
| Elongation, A | 6% min | 6% min |
| Hardness after tempering | approx. 41-48 HRC | approx. 400-470 HB |
| Modulus of elasticity, E | 210 GPa | 30.5 x 106 psi |
| Density | 7.78 g/cm³ | 0.281 lb/in³ |
Values apply to test pieces cut from small sections. Achievable strength falls as ruling section grows. Tell us the finished section and we quote a property target that can be met through the wall.
| Condition | Symbol | Max hardness |
|---|---|---|
| Treated for shearability | +S | 280 HB |
| Soft annealed | +A | 248 HB |
| Annealed to spheroidise carbides | +AC | 230 HB |
Forging and heat treatment of 1.7701
| Operation | Temperature | Cooling and result |
|---|---|---|
| Forging | 1100 to 850 °C | Finish above 850 °C, then cool slowly in furnace or ash to avoid quench cracks |
| Soft annealing | 640-680 °C | Slow cool, gives a maximum of 255 HB for machining |
| Normalising | 850-880 °C | Air cool, refines the as-forged structure |
| Hardening | 830-860 °C | Oil quench |
| Tempering | 350-550 °C | Sets final hardness, lower end for spring hardness, upper end for toughness |
| Stress relieving | approx. 30-50 °C below the tempering temperature | After heavy machining, slow cool in furnace |
Vanadium changes how the grade should be soaked. Long holds at the austenitising temperature dissolve very little extra vanadium carbide and coarsen the grain, so hold times are kept short and repeatable. On heavy forgings we work to about one hour per 25 mm of ruling section once the piece has equalised.
How we make a 1.7701 forging
- Steelmaking and ingot supplyElectric arc furnace steel with ladle refining and vacuum degassing, cast to ingot and released against the ladle analysis before it enters our shop.
- Heating and open-die forgingIngots are soaked and forged on hydraulic presses and hammers with upsetting and drawing passes to break down the cast structure and reach a forging ratio of at least 3:1.
- Ring rolling where the shape calls for itUpset and punched preforms are rolled into seamless rings so the grain follows the circumference instead of being cut through by machining.
- Post-forge cooling and annealingControlled slow cooling followed by soft annealing at 640-680 °C, which brings hardness under 255 HB and removes forging stress.
- Quench and temperAustenitise at 830-860 °C, oil quench, then temper at 350-550 °C to the hardness or strength band on your order.
- Rough machining and testingTurned or milled to your allowance, then ultrasonic testing to EN 10228-3 or ASTM A388, a hardness survey and tensile and impact tests from a prolongation.
- Documentation and dispatchEN 10204 3.1 certificate with ladle analysis, heat-treatment chart, mechanical results and dimensional report, then marking, rust prevention and packing for sea or air freight.
1.7701 forged shapes we supply
| Forged form | Size range | Typical use |
|---|---|---|
| Round bars and shafts | 100-1200 mm dia, length to 12000 mm | Torsion bars, spindles, stepped shafts, mandrels |
| Square, flat and hexagonal bars | 100-1000 mm across flats | Die blocks, machine components, tool holders |
| Hollow bars, sleeves, bushings, cylinders | OD 200-2000 mm, ID from 100 mm | Housings, shells, hydraulic cylinder bodies |
| Seamless rolled rings | OD 300-6000 mm, height to 1000 mm | Bearing rings, gear blanks, flange rings |
| Discs, blocks and forged plates | 200-2500 mm dia, thickness 40-800 mm | Tube sheets, spacers, die plates |
| Mill rolls | Barrel 80-1200 mm dia | Work rolls, back-up rolls, leveller and straightening rolls, scale-breaker rolls for pickling lines |
Single-piece weight runs from 10 kg to 15 tonnes, forged on 1, 3, 6 and 9 tonne hammers and a 4500 tonne hydraulic press, with ring rolling mills of 3 m and 6 m. Larger pieces are quoted case by case against ingot availability. Send the drawing and we confirm in writing.
Designations and cross-references
| System | Designation | Note |
|---|---|---|
| EN material number | 1.7701 | Primary reference used on our certificates |
| EN chemical designation | 52CrMoV4 | EN 10089:2002, hot-rolled steels for quenched and tempered springs |
| DIN | 51CrMoV4 | Former German designation for the same material number |
| AISI / SAE | 4150, approximate | Similar C, Cr and Mo, with no specified vanadium |
| Common trade names | Cr-Mo-V spring steel | Also written 52 CrMoV 4 or 51 CrMoV 4 |
Cross-references are for guidance only. Confirm the grade and standard on your drawing before ordering and we forge to the specification you name rather than to a substitute.
Where 1.7701 is used
- Heavily stressed automotive springs, torsion bars and stabiliser bars
- Coil, threaded and torsion springs that have to resist relaxation under load
- Machine and engine components carrying high cyclic stress
- Debarking knives in pulp and paper mills
- Forged tooling such as mandrels, die blocks, punches and holders
- Rolls for cut-to-length and tension-levelling lines, galvanising and electrolytic tinning lines, and scale-breaker rolls for thin-gauge material in pickling-line cassettes
Testing and documents
Testing is agreed at order stage and reported on one certificate, so your incoming inspection has a single document to check against the purchase order.
- Chemical analysis: ladle analysis as standard, product analysis on request
- Mechanical testing: tensile, impact and hardness from a prolongation heat treated with the forging
- Ultrasonic testing: EN 10228-3, ASTM A388 or SEP 1921, acceptance class stated on the order
- Surface testing: magnetic particle to ASTM E709 or dye penetrant where specified
- Grain size and microstructure: ASTM E112, with photomicrographs on request
- Dimensional report: measured against your drawing before packing
- Certification: EN 10204 3.1 as standard, 3.2 witnessed by TÜV, SGS, BV or Lloyd's Register on request
Frequently asked questions about 1.7701
What is steel 1.7701?
1.7701 is the European material number for 52CrMoV4, a chromium-molybdenum-vanadium alloy steel listed in EN 10089:2002 for hot-rolled quenched and tempered spring steels. It carries about 0.5% carbon with 1% chromium, 0.2% molybdenum and 0.15% vanadium, which gives high fatigue strength and resistance to relaxation after oil quenching and tempering.
Is 1.7701 the same as 52CrMoV4 and 51CrMoV4?
Yes. 52CrMoV4 is the current EN chemical designation for material number 1.7701, and 51CrMoV4 is the older DIN name for the same steel. Jiangyin Jiangnan Metal Co., Ltd. supplies forgings against either designation and prints both on the EN 10204 3.1 certificate.
What is the AISI equivalent of 1.7701?
AISI 4150 is the closest American grade in carbon, chromium and molybdenum content. It carries no specified vanadium, so treat it as a cross-reference rather than a drop-in substitute. Where vanadium grain refinement matters, order to EN 10089 52CrMoV4 chemistry.
What hardness and strength can 1.7701 reach after quenching and tempering?
Hardened from 830-860 °C in oil and tempered at 350-550 °C, 1.7701 typically reaches 1370-1670 N/mm² tensile strength, a 0.2% proof stress near 1180 N/mm² and about 41-48 HRC, with elongation around 6%. Achievable values fall as ruling section increases, so heavy forgings are quoted with a property target set for the section.
What forged shapes are available in 1.7701?
Jiangyin Jiangnan Metal Co., Ltd. forges 1.7701 into round, square, flat and hexagonal bars, stepped shafts, hollow bars, sleeves, bushings and cylinders, seamless rolled rings, discs, blocks and plates, and mill rolls including work rolls, back-up rolls and leveller rolls.
What is the largest 1.7701 forging you can produce?
Our shop covers single pieces from about 10 kg to 15 tonnes, forged diameters of 100-1200 mm and lengths up to 12000 mm, with seamless rolled rings up to 6000 mm outside diameter on the 6 m ring mill. Send a drawing to sales@steelforgepieces.com and we confirm feasibility against the ingot size.
Do you supply EN 10204 3.1 or 3.2 certificates for 1.7701 forgings?
Every 1.7701 forging ships with an EN 10204 3.1 certificate covering ladle analysis, heat treatment record, mechanical test results and a dimensional report. EN 10204 3.2 certification witnessed by TÜV, SGS, BV or Lloyd's Register is available when it is requested at order stage.
How is 1.7701 forged and heat treated?
Forge 1.7701 between about 1100 °C and 850 °C, then cool slowly to avoid cracking in this medium-carbon Cr-Mo-V steel. Soft annealing at 640-680 °C with slow cooling gives a maximum of 255 HB for machining, normalising is done at 850-880 °C, and the final quench and temper is 830-860 °C in oil followed by tempering at 350-550 °C.
What is the lead time for 1.7701 forgings from China?
Typical lead time is 25-45 days after drawing approval, depending on forging size, heat treatment cycle and machining allowance. Rough-machined and ultrasonically tested pieces sit at the upper end of that range. Quotations are issued within one working day of receiving a drawing or dimension list.
What is 1.7701 used for?
1.7701 is used for heavily stressed automotive springs and torsion bars, threaded and coil springs, machine and engine components, debarking knives in pulp mills, and forged tooling such as mandrels, dies and mill rolls where high fatigue strength and resistance to relaxation are required.
About the manufacturer
Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging factory in Jiangyin, Jiangsu, on the south bank of the Yangtze between Shanghai and Nanjing. We forge carbon, alloy, tool and stainless steels and nickel alloys into bars, shafts, sleeves, seamless rolled rings, discs and rolls, and we ship through Shanghai and Zhangjiagang.
The works runs 1, 3, 6 and 9 tonne open-die forging hammers, a 4500 tonne hydraulic press and seamless ring rolling mills of 3 m and 6 m, with our own heat-treatment, machining and testing departments. The company employs around 460 people, including 9 senior engineers and 32 intermediate engineers.
Jiangyin Jiangnan Metal Co., Ltd.
No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China
Telephone +86 189 2135 9659. Email sales@steelforgepieces.com
Website www.steelforgepieces.com. Office hours 08:00 to 17:30 China Standard Time, Monday to Saturday.
Data sources
Composition limits and maximum delivery hardness on this page follow EN 10089:2002. The typical ladle analysis and the heat-treatment temperatures come from mill data for heats we have processed.
Designation cross-references follow the DIN and AISI tables in common use. Forging sizes, production route and testing scope describe work carried out at our own plant in Jiangyin.
Page reviewed on by our metallurgical department.
Get a quotation for 1.7701 forgings
Send a drawing or a dimension list and we come back within one working day with price, weight, lead time and the heat-treatment route we propose. To price it accurately we need:
- Grade and standard, here 1.7701 / 52CrMoV4 to EN 10089
- Rough or finished dimensions, and machining allowance if any
- Quantity and required delivery date
- Delivery condition: annealed, normalised, or quenched and tempered to a hardness or strength band
- Testing and certification: EN 10204 3.1 or 3.2, UT class, impact test temperature