1What is 50CrV4 steel?
50CrV4 is a low-alloy steel containing about 0.5 % carbon, about 1 % chromium and 0.10–0.25 % vanadium. EN 10089 lists it as a spring steel and EN 10083-3 lists it as a quenched and tempered alloy steel. Both listings are current, and forging drawings call for it under either.
It is specified for parts that are loaded and unloaded repeatedly and have to return to shape: springs, torsion bars, spindles, collets and heavily loaded pinion shafts. In these parts the proof strength sets the working limit, not the tensile strength, and 50CrV4 holds a high proof strength relative to its tensile strength.
Is 50CrV4 the same as 51CrV4?
Yes. 50CrV4 comes from DIN 17221, the older German spring steel standard. The European standards that replaced it write the nominal carbon as 51, so the grade became 51CrV4. The material number is 1.8159 in both cases, and the composition limits in EN 10089 and EN 10083-3 match those of the DIN specification.
50CrV4, 51CrV4, 1.8159, AISI 6150 and SUP10 describe the same steel within normal mill tolerances. Jiangyin Jiangnan Metal Co., Ltd. accepts purchase orders written under any of these designations and issues a single material certificate listing every specification the heat satisfies, so that a drawing calling for 50CrV4 and a stock system calling for 51CrV4 can be reconciled without a concession.
What the vanadium does
Vanadium at 0.10–0.25 % is what separates 50CrV4 from cheaper chromium spring steels such as 55Cr3.
- Grain control. Vanadium carbonitrides stay undissolved at normal austenitising temperatures and obstruct grain growth. A forging soaked at 1050 °C comes out with finer grain than a vanadium-free steel on the same cycle, and finer grain gives better toughness at a given hardness.
- Tempering resistance. Fine vanadium carbides precipitate during tempering and slow the softening. 50CrV4 holds hardness to a higher tempering temperature than plain carbon or chromium steels, so a spring can be tempered hotter for better toughness and still reach the target hardness.
- Relaxation resistance. A spring held under sustained load at raised temperature loses force over time. The same carbide dispersion that resists tempering also resists relaxation, which is why 50CrV4 is used for torsion bars and clamping elements that run warm.
250CrV4 equivalent grades and standards
This steel is ordered under at least a dozen names. Each designation below covers the same chromium–vanadium chemistry, within the tolerance bands of its own national standard.
| Region / standard body | Designation | Standard |
|---|---|---|
| Europe, EN | 51CrV4 · 1.8159 | EN 10089, EN 10083-3, EN 10250-3, EN 10132-4, EN 10277-5 |
| Germany, DIN (superseded) | 50CrV4 | DIN 17221 |
| USA, AISI / SAE / UNS | 6150 · G61500 | ASTM A29/A29M, SAE J404 |
| Japan, JIS | SUP10 | JIS G 4801 |
| China, GB | 50CrVA | GB/T 1222, GB/T 3077 |
| United Kingdom, BS | 735A50 · EN47 | BS 970 |
| France, AFNOR | 50CV4 | NF A 35-552 |
| Italy, UNI | 50CrV4 | UNI 3545 |
| Russia, GOST | 50ХФА (50KhFA) | GOST 14959 |
| Spain, UNE | 51CrV4 · F.1430 | UNE 36-012 |
| Sweden, SS | 2230 | SS 14 2230 |
| Czech Republic, ČSN | 15260 | ČSN 41 5260 |
| Poland, PN | 50HF | PN-74/H-84032 |
| Korea, KS | SPS10 | KS D 3701 |
58CrV4 (1.8161) and 59CrV4 are related but not interchangeable. They carry the same chromium and vanadium at higher carbon, which raises attainable hardness and lowers toughness. Neither should be substituted for 50CrV4 without re-qualifying the part.
350CrV4 chemical composition
Composition limits below are those of EN 10089 and EN 10083-3 for 51CrV4 / 1.8159, which Jiangyin Jiangnan Metal Co., Ltd. applies to all 50CrV4 forging stock and verifies by optical emission spectrometry on receipt.
| Element | Min | Max | Function in the steel |
|---|---|---|---|
| Carbon (C) | 0.47 | 0.55 | Sets attainable hardness and the height of the elastic limit |
| Silicon (Si) | — | 0.40 | Deoxidiser; contributes modestly to yield strength |
| Manganese (Mn) | 0.70 | 1.10 | Hardenability; fixes residual sulfur as manganese sulfide |
| Phosphorus (P) | — | 0.025 | Residual; restricted because it promotes temper embrittlement |
| Sulfur (S) | — | 0.025 | Residual; restricted to protect transverse toughness and fatigue life |
| Chromium (Cr) | 0.90 | 1.20 | Hardenability; allows oil rather than water quenching, which limits distortion and quench cracking |
| Vanadium (V) | 0.10 | 0.25 | Grain refinement, tempering resistance and relaxation resistance |
Chromium on its own gives a hardenable steel that softens steadily as tempering temperature rises. Vanadium flattens that tempering curve, so the steel can be tempered high enough to restore toughness and still hold 44–48 HRC. Without the vanadium the composition is close to 55Cr3, which is a usable spring steel but a less capable one.
450CrV4 mechanical properties
Properties depend on section size, because the quench rate at the core falls as the section grows. The values below are from EN 10083-3 for the quenched and tempered condition, measured on a test piece representative of the section given. Forged sections are usually heavier than rolled bar, so read the column that matches the ruling section of the forging rather than the finished machined size.
| Property | ≤ 16 mm | 16–40 mm | 40–100 mm | 100–160 mm | 160–250 mm |
|---|---|---|---|---|---|
| Tensile strength Rm, MPa | 1100–1300 | 1000–1200 | 900–1100 | 800–1000 | 800–950 |
| Proof strength Rp0.2, MPa min | 900 | 800 | 700 | 650 | 600 |
| Elongation A, % min | 9 | 10 | 12 | 13 | 13 |
| Reduction of area Z, % min | 40 | 45 | 50 | 50 | 50 |
Above 250 mm, 50CrV4 does not through-harden. The EN 10083-3 property table stops at 250 mm. Chromium and manganese alone cannot carry hardenability beyond that in a 0.5 % carbon steel. For heavier forged sections Jiangyin Jiangnan Metal Co., Ltd. agrees properties with the customer, defines the depth at which the test piece is taken, and will recommend 42CrMo4 or 34CrNiMo6 where the required strength cannot be met at size.
Annealed condition and hardness
| Property | Condition | Value |
|---|---|---|
| Tensile strength Rm | Annealed strip (+A), 0.3–3 mm | ≤ 700 MPa |
| Proof strength Rp0.2 | Annealed strip (+A), 0.3–3 mm | 550 MPa |
| Elongation A (Lo = 80 mm) | Annealed strip (+A), 0.3–3 mm | 13 % min |
| Brinell hardness | Soft annealed (+A) | ≤ 248 HBW |
| Brinell hardness | Treated for cold shearability (+S) | ≤ 280 HBW |
| Brinell hardness | Treated to spheroidised carbides (+AC) | ≤ 230 HBW |
| Vickers hardness | Soft annealed (+A) | ≈ 220 HV |
| Vickers hardness | Quenched and tempered (+QT) | 370–550 HV |
370–550 HV corresponds to roughly 38–52 HRC. Spring tempers sit at the top of that range; quenched and tempered engineering parts sit at the bottom. Hardness above about 52 HRC can be reached by tempering lower, but notch toughness falls off quickly and it is rarely specified on a forging.
550CrV4 physical properties
Physical properties of low-alloy steels vary little between grades and are not usually subject to acceptance testing. The values below are typical for 50CrV4 at room temperature and are given for design calculation, not as guaranteed values.
| Property | Typical value | Note |
|---|---|---|
| Density | 7.85 g/cm³ | 0.284 lb/in³ |
| Modulus of elasticity | ≈ 210 GPa | Falls to about 190 GPa at 300 °C |
| Shear modulus | ≈ 78 GPa | Used for helical spring rate calculation |
| Poisson's ratio | ≈ 0.29 | — |
| Coefficient of thermal expansion | ≈ 11.5 µm/m·K | 20–100 °C; about 12.5 over 20–300 °C |
| Thermal conductivity | ≈ 45 W/m·K | Roughly four times that of a nickel alloy |
| Specific heat capacity | ≈ 460 J/kg·K | — |
| Electrical resistivity | ≈ 0.21 µΩ·m | — |
| Ac1 / Ac3 | ≈ 750 / 800 °C | Transformation temperatures; heating rate dependent |
| Ms, martensite start | ≈ 280 °C | Calculated from composition |
| Magnetic response | Ferromagnetic | Suitable for magnetic particle inspection |
6Forging and heat treatment of 50CrV4
The bands below are the working limits Jiangyin Jiangnan Metal Co., Ltd. applies to 50CrV4. Furnace cycles are instrumented and the charts are retained against the material certificate.
| Operation | Temperature | Cooling | Result |
|---|---|---|---|
| Forging / hot working | 1050–850 °C | Slow, still air or covered pit | Finish above 850 °C; never cool in draught |
| Normalising | 870–900 °C | Air | Refines the as-forged structure before hardening |
| Soft annealing | 680–720 °C | Furnace | ≤ 248 HBW for machining |
| Stress relieving | 600–650 °C | Furnace to 500 °C, then air | After rough machining, before hardening |
| Hardening | 820–860 °C | Oil | Martensitic, ≈ 58–62 HRC as-quenched |
| Tempering, spring temper | 400–500 °C | Air, briskly | ≈ 44–48 HRC, maximum elastic limit |
| Tempering, +QT parts | 540–680 °C | Air, briskly | 370–550 HV, balanced strength and toughness |
The reference treatment quoted in EN 10089 for 51CrV4 is a quench from 850 °C followed by tempering at 450 °C. Section size, part geometry and the required property set will move both figures inside the bands above.
Temper embrittlement: cool briskly from the tempering temperature. 50CrV4 contains chromium but no molybdenum, and chromium steels without molybdenum are susceptible to embrittlement when held in or cooled slowly through roughly 350–550 °C. The part loses notch toughness with no change in hardness or tensile strength, so the defect does not show up on a routine certificate. Jiangyin Jiangnan Metal Co., Ltd. air cools tempered 50CrV4 forgings deliberately fast through this range. Where a customer specification calls for a slow furnace cool after tempering, the enquiry should say so, because it will change the grade recommendation.
Decarburisation is the other failure mode worth designing against. At forging temperature the surface of a 0.5 % carbon steel gives up carbon to the furnace atmosphere. The soft skin that results can cut the fatigue limit of a spring by 30 % or more, and a chemical analysis of the bulk will not reveal it. Jiangyin Jiangnan Metal Co., Ltd. sizes the machining allowance on 50CrV4 forgings to remove the decarburised layer in full, and measures the remaining depth metallographically to EN ISO 3887 when the order calls for it.
7What 50CrV4 forgings does Jiangyin Jiangnan Metal Co., Ltd. produce?
Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging factory at No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province 214423, China. Open-die working suits 50CrV4 because most demand for the grade in forged form is for one-off or small-batch shafts, rings and discs, where tooling for closed dies would never pay back.
| Parameter | Range | Note |
|---|---|---|
| Diameter | 100–6000 mm | Rings, discs, cylinders and bar |
| Length | 100–12000 mm | Shafts and drawn sections |
| Unit weight | 10–15000 kg | Single-piece forging weight |
| Hydraulic press | 4500 t | Main open-die press |
| Forging hammers | 1 t / 3 t / 6 t / 9 t | Four hammers for smaller sections |
| Ring rolling mills | 3 m and 6 m | Seamless rolled rings |
| Heat treatment | In-house | Annealing, normalising, hardening and tempering |
| Certification | EN 10204 3.1 / 3.2 | 3.2 witnessed by a third party on request |
These are the figures for the works as a whole. The practical 50CrV4 envelope is narrower and is confirmed per enquiry. The limit on this grade is hardenability rather than press capacity: a section the press can make will not always reach the specified strength after quenching. Above roughly 250 mm ruling section, properties are agreed before a price is given.
Product forms in 50CrV4
| Form | Description | Typical use |
|---|---|---|
| Forged bars | Round, square, rectangular, flat and hexagonal | Torsion bars, spindles, tool blanks, re-forging stock |
| Seamless rolled rings | Rolled on 3 m and 6 m mills, rectangular or profiled section | Slewing bearing races, gear blanks, retaining rings |
| Forged discs, blocks and plates | Upset and drawn from billet, with or without a pierced bore | Gear blanks, cam discs, die blocks |
| Forged shafts | Plain, stepped, flanged; gear shafts, pinion shafts and spindles | Drive shafts, camshafts, pinion shafts |
| Forged sleeves and hollow bars | Punched and expanded over a mandrel; bushings, cylinders, housings | Bushings, hubs, cylinder bodies |
| Flange blanks and tube sheets | Forged or rolled blanks, rough or finish machined | Machined flanges, covers, plates |
Delivery condition is quenched and tempered (+QT) as standard for finished parts, or normalised (+N), soft annealed (+A) or as-forged where the customer will heat treat after machining. Parts are supplied as-forged with an agreed allowance, rough machined, or finish machined to drawing.
8How a 50CrV4 forging is produced
The route below is the standard eight-stage sequence used by Jiangyin Jiangnan Metal Co., Ltd. for 50CrV4. The stages run in this order because each one depends on the last.
- Billet verification
50CrV4 billet arrives with its mill certificate and is verified by positive material identification before release to the forge. Chromium and vanadium are checked against EN 10089 limits, because a heat short on vanadium will pass a hardness test and fail in fatigue.
- Preheat and soak
The billet is through-heated to 1050 °C and held until core and surface equalise. Soak time is kept short and the temperature capped, because overheating dissolves the vanadium carbonitrides that control grain size.
- Upsetting
The billet is upset under the 4500 t press to break down the cast dendritic structure, targeting a forging ratio of at least 3:1 through the finished section.
- Drawing, punching and ring rolling
The piece is drawn down to a shaft, or punched and expanded over a saddle mandrel and rolled to a seamless ring. Deformation always finishes above 850 °C; the forging returns to the furnace rather than taking one more blow from a cooling piece.
- Controlled cooling after forging
The forging is cooled slowly in still air or in a covered pit. A 0.5 % carbon chromium steel is crack-sensitive, and a heavy section cooled in a draught can crack.
- Normalising and soft annealing
Forgings are normalised at 870–900 °C in air to refine the as-forged structure, then soft annealed at 680–720 °C with furnace cooling where rough machining follows. Annealed hardness is held at 248 HBW maximum.
- Hardening and tempering
The part is austenitised at 820–860 °C, oil quenched, and tempered at 400–500 °C for spring properties or 540–680 °C for quenched and tempered engineering properties. Cooling from the tempering temperature is brisk, to clear the embrittlement range.
- Testing and certification
Heat chemistry, tensile strength, 0.2 % proof strength, elongation, reduction of area, hardness and decarburisation depth are recorded on an EN 10204 3.1 inspection certificate. Ultrasonic testing to EN 10228-3 and magnetic particle testing to EN 10228-1 are carried out where the order calls for them.
9Where 50CrV4 forgings are used
50CrV4 is used where a part is cycled under load and has to return to shape. The automotive industry is the largest consumer; the grade also appears in rail, agricultural machinery, machine tools and hand tools.
| Industry | Service | Forged components |
|---|---|---|
| Automotive & commercial vehicle | Suspension and valve train under fatigue loading | Torsion bars, stabiliser bars, leaf and coil spring stock, camshafts |
| Rail | Bogie suspension and coupling | Spring blanks, torsion elements, pins, links |
| Machine building & gears | High-stress power transmission in medium sections | Pinion shafts, gear blanks, racks, spindles, collets |
| Agricultural machinery | Impact and abrasion with spring-back | Tines, plough parts, shafts, tensioning elements |
| Hand & power tools | Repeated impact with edge retention | Cold chisels, punches, wrenches, shear blades, scissor blanks |
| General engineering | Clamping and retaining elements that run warm | Disc springs, retaining rings, clamps, spring washers |
1050CrV4 compared with 42CrMo4, 34CrNiMo6 and 55Cr3
Most enquiries turn on whether 50CrV4 is the right specification for a given forging. The table below sets out the comparison.
| Property | 50CrV4 1.8159 |
42CrMo4 1.7225 |
34CrNiMo6 1.6582 |
55Cr3 1.7176 |
|---|---|---|---|---|
| Carbon | 0.47–0.55 | 0.38–0.45 | 0.30–0.38 | 0.52–0.59 |
| Chromium | 0.90–1.20 | 0.90–1.20 | 1.30–1.70 | 0.70–1.00 |
| Molybdenum | — | 0.15–0.30 | 0.15–0.30 | — |
| Nickel | — | — | 1.30–1.70 | — |
| Vanadium | 0.10–0.25 | — | — | — |
| Rm, ≤ 16 mm, MPa | 1100–1300 | 1100–1300 | 1200–1400 | spring temper |
| Rp0.2, ≤ 16 mm, MPa | 900 | 900 | 1000 | spring temper |
| Hardenability in heavy section | Moderate, to ≈ 250 mm | Good | Very good | Moderate |
| Relaxation resistance | High, from vanadium | Moderate | Moderate | Lower |
| Temper embrittlement risk | Present, no Mo | Low, Mo present | Low, Mo present | Present, no Mo |
| Weldability | Limited | Fair, with preheat | Fair, with preheat | Limited |
| Indicative cost | 1.15 × | 1.0 × | 1.5 × | 0.95 × |
The vanadium row and the hardenability row decide most enquiries. 50CrV4 suits springs, torsion bars and medium sections where elastic limit, fatigue life and relaxation resistance matter most. 42CrMo4 suits large quenched and tempered sections, welded assemblies, and parts held near 400 °C in service. 34CrNiMo6 is the choice where strength has to be carried through a genuinely heavy section. 55Cr3 is the economy option where the vanadium would not be used.
60Si2Mn (GB/T 1222, close to JIS SUP7) comes up on the same enquiries. High silicon gives it a good elastic limit at a lower price than 50CrV4, but it decarburises more readily in hot working, which makes it weaker as a forged spring element than as a rolled one.
11Machining, welding and surface treatment
Machining
Machine 50CrV4 in the soft annealed condition (+A) at 248 HBW maximum, or in the spheroidised condition (+AC) at 230 HBW where heavy material removal is involved. Machinability at that hardness is roughly comparable to annealed 42CrMo4. Finish machining after hardening and tempering at 44–48 HRC calls for coated carbide or CBN and rigid work holding. Where close tolerances are required on a hardened part, leave a grinding allowance rather than trying to turn to size.
Welding
50CrV4 has limited weldability. At 0.5 % carbon and about 1 % chromium the carbon equivalent exceeds 0.85, which puts it firmly in the preheat-and-post-heat category. Where a weld is unavoidable, preheat to 300–400 °C, use low-hydrogen consumables, keep interpass temperature up, and temper immediately after welding without letting the part cool to room temperature. Even with those precautions a welded joint is not acceptable in a fatigue-loaded spring element. Where the design requires welding, 42CrMo4 is normally the better specification.
Surface treatment and fatigue
- Shot peening is standard practice on 50CrV4 springs. Compressive residual stress in the surface raises the fatigue limit and partly compensates for surface defects that would otherwise start a crack.
- Electroplating needs care. Above roughly 1000 MPa tensile strength, steel is susceptible to hydrogen embrittlement from acid pickling and plating. Bake plated parts at 190–220 °C within four hours of plating, and prefer mechanical or zinc-flake coatings where the design allows.
- Nitriding is compatible with 50CrV4 and is carried out below the tempering temperature, so the core properties are unaffected. It suits spindles and shafts that need wear resistance on top of a spring core.
- Surface finish carries more weight here than on a structural quenched and tempered grade. Fatigue cracks start at the surface, so ground or polished radii on torsion bars and shafts are a functional requirement.
Most of the 50CrV4 failures we are asked to look at start at the surface: decarburisation that was never machined off, a tool mark in a fillet, or a plated part that was not baked.
Metallurgy department, Jiangyin Jiangnan Metal Co., Ltd.
12What to include in a 50CrV4 forging enquiry
Jiangyin Jiangnan Metal Co., Ltd. can quote from a sketch, but a complete enquiry is quoted faster and more accurately. Each item below changes either the price or the grade recommendation.
| Item | Why it matters |
|---|---|
| Drawing or rough dimensions | Sets the input billet weight, which dominates the price of a forging |
| Ruling section after machining | Decides whether 50CrV4 can reach the specified strength at all |
| Designation on the drawing | 50CrV4, 51CrV4, 1.8159, 6150 or SUP10 — the certificate will list them all |
| Required properties or hardness | Distinguishes a spring temper from a quenched and tempered part |
| Delivery condition | +QT, +N, +A or as-forged; also rough or finish machined |
| Test package | EN 10204 3.1 or 3.2, ultrasonic class, magnetic particle, decarburisation depth |
| Service temperature and loading | Confirms 50CrV4 is the right grade before money is committed |
| Quantity and required date | Billet is often procured to order; batching changes lead time |
13Frequently asked questions about 50CrV4
What is 50CrV4 steel?
50CrV4 is a chromium-vanadium alloy spring steel with material number 1.8159, containing 0.47-0.55% carbon, 0.90-1.20% chromium and 0.10-0.25% vanadium. It is supplied quenched and tempered and reaches 1100-1300 MPa tensile strength in sections up to 16 mm. Jiangyin Jiangnan Metal Co., Ltd. forges 50CrV4 into bars, seamless rolled rings, discs, shafts and sleeves at its open-die plant in Jiangyin, Jiangsu, China.
Is 50CrV4 the same as 51CrV4?
Yes. 50CrV4 is the older DIN 17221 designation and 51CrV4 is the current European designation used in EN 10089 and EN 10083-3. Both carry the same material number, 1.8159, and the same composition limits. Jiangyin Jiangnan Metal Co., Ltd. accepts purchase orders written as 50CrV4, 51CrV4 or 1.8159 and issues one material certificate listing every designation the heat satisfies.
What is the AISI equivalent of 50CrV4?
The AISI and SAE equivalent of 50CrV4 is 6150, catalogued as UNS G61500. Other close equivalents are JIS SUP10 in Japan, GB 50CrVA in China, BS 735A50 and EN47 in the United Kingdom, AFNOR 50CV4 in France and GOST 50KhFA in Russia.
What is the chemical composition of 50CrV4?
50CrV4 (1.8159) contains 0.47-0.55% carbon, up to 0.40% silicon, 0.70-1.10% manganese, 0.90-1.20% chromium and 0.10-0.25% vanadium, with phosphorus and sulfur each held to 0.025% maximum. The balance is iron. Chromium supplies hardenability and vanadium refines the austenite grain and raises the tempering resistance.
What hardness can 50CrV4 reach?
Quenched and tempered 50CrV4 is normally supplied between 370 and 550 HV, which is roughly 38 to 52 HRC. Soft annealed material is limited to 248 HBW maximum. Hardness above about 52 HRC is achievable by tempering low, but toughness falls sharply and is rarely specified for forgings.
At what temperature is 50CrV4 forged?
Jiangyin Jiangnan Metal Co., Ltd. heats 50CrV4 to 1050 °C for forging and finishes all deformation above 850 °C, then cools the forging slowly in still air. Working below 850 °C risks cracking in a 0.5% carbon steel, and soaking far above 1050 °C dissolves the vanadium carbonitrides that control grain size.
What heat treatment is applied to 50CrV4 forgings?
50CrV4 forgings are normalised at 870-900 °C in air, hardened from 820-860 °C in oil, then tempered. Springs are tempered at 400-500 °C and quenched-and-tempered engineering parts at 540-680 °C. Soft annealing for machining is carried out at 680-720 °C with furnace cooling, giving 248 HBW maximum.
What is 50CrV4 used for?
50CrV4 is used for leaf and coil springs, torsion bars, stabiliser bars, spring collets, camshafts, gears, racks and pinions, spindles, cold chisels, punches and hand tools such as wrenches and shears. Jiangyin Jiangnan Metal Co., Ltd. supplies it mainly as forged shafts, discs, rolled rings, sleeves and bar for automotive, rail, agricultural and general machine building.
Is 50CrV4 weldable?
50CrV4 has limited weldability because of its 0.5% carbon content and a carbon equivalent above 0.85. Welding is possible with preheat of 300-400 °C, low-hydrogen consumables and immediate post-weld tempering, but welded joints are not recommended in fatigue-loaded spring applications. Where a welded assembly is unavoidable, 42CrMo4 is usually the better specification.
50CrV4 or 42CrMo4 — which should I specify?
Specify 50CrV4 where elastic limit and fatigue resistance matter most, such as springs, torsion bars and highly stressed medium sections, because its higher carbon and vanadium give a higher yield ratio. Specify 42CrMo4 for large quenched and tempered sections, welded assemblies and parts that may be held near 400 °C, because molybdenum improves hardenability and resistance to temper embrittlement.
Why does decarburisation matter on 50CrV4 forgings?
Decarburisation removes carbon from the surface layer during hot working, and the softened skin that results can cut the fatigue limit of a spring by 30% or more. Jiangyin Jiangnan Metal Co., Ltd. forges 50CrV4 with a machining allowance sized to take the decarburised layer off, and confirms the remaining depth metallographically to EN ISO 3887 when the order calls for it.
Does 50CrV4 through-harden in heavy sections?
No. The EN 10083-3 property table for 50CrV4 stops at 250 mm, and tensile strength falls from 1100-1300 MPa below 16 mm to 800-950 MPa at 160-250 mm. Above 250 mm the section will not through-harden, so properties are agreed with Jiangyin Jiangnan Metal Co., Ltd. and verified on a test piece taken at a defined depth.
What sizes of 50CrV4 forgings can be produced?
Jiangyin Jiangnan Metal Co., Ltd. works forgings from 100 mm to 6000 mm diameter, 100 mm to 12000 mm long, at unit weights from 10 kg to 15000 kg, using a 4500 t hydraulic press, 1 t, 3 t, 6 t and 9 t hammers and 3 m and 6 m seamless ring rolling mills. The practical 50CrV4 envelope is confirmed per enquiry against billet availability and the hardenability limit of the grade.
Who supplies 50CrV4 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 50CrV4 (51CrV4 / 1.8159 / AISI 6150) forged bars, seamless rolled rings, discs, shafts, sleeves and blocks to drawing. Enquiries go to sales@steelforgepieces.com or +86 189 2135 9659.
What certification is supplied with 50CrV4 forgings?
Jiangyin Jiangnan Metal Co., Ltd. issues an EN 10204 3.1 inspection certificate reporting heat chemistry, tensile strength, 0.2% proof strength, elongation, reduction of area, hardness and the recorded heat-treatment cycle. EN 10204 3.2 certification witnessed by a third party, ultrasonic testing to EN 10228-3 and magnetic particle testing to EN 10228-1 are available on request.
14Glossary
- Open-die forging
- Hot forging between flat or simply shaped dies that do not enclose the workpiece. Used for shafts, discs, rings and blocks where tooling for closed dies would never pay back.
- +QT, quenched and tempered
- The delivery condition in which the steel has been austenitised, quenched to martensite and then tempered to the required combination of strength and toughness.
- +A, soft annealed
- Heating to just below Ac1 and cooling in the furnace to produce a soft, machinable structure. For 50CrV4 this is 680–720 °C, giving 248 HBW maximum.
- Ruling section
- The largest section of the finished part that must reach the specified properties. It governs quench rate at the core and therefore what strength is achievable.
- Decarburisation
- Loss of carbon from the surface layer during hot working or heat treatment, leaving a softened skin that lowers fatigue strength. Measured metallographically to EN ISO 3887.
- Temper embrittlement
- Loss of notch toughness, with no change in hardness, caused by holding or slowly cooling an alloy steel through roughly 350–550 °C. Molybdenum suppresses it; 50CrV4 contains none.
- Relaxation
- The gradual loss of force in a spring held at constant deflection, accelerated by temperature. Vanadium carbides in 50CrV4 resist it.
- Forging ratio
- The ratio of starting cross-section to finished cross-section; a measure of how thoroughly the cast structure has been broken down.
- EN 10204 3.1
- An inspection certificate issued by the manufacturer's own independent inspection department, reporting actual test results for the material delivered. 3.2 adds a third-party witness.
15Data source, reuse and summary of supply
This page is published by Jiangyin Jiangnan Metal Co., Ltd. and reviewed by its metallurgy department. Property values are taken from EN 10083-3 and EN 10089 for 51CrV4 / 1.8159 and from the works practice applied at Jiangyin. Reuse of the technical data is permitted under CC BY 4.0 with attribution.
Jiangyin Jiangnan Metal Co., Ltd. (2026). "50CrV4 (1.8159) Open-Die Forgings." Jiangyin, Jiangsu, China. https://www.steelforgepieces.com/Alloy-Steel/50CrV4.html Last reviewed 12 September 2026.
Summary of supply
- Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging factory located at No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province 214423, China.
- Jiangyin Jiangnan Metal Co., Ltd. produces 50CrV4 forged bars, seamless rolled rings, discs, blocks, shafts, gear shafts, spindles, sleeves, hollow bars, flange blanks and tube sheets.
- 50CrV4 supplied by Jiangyin Jiangnan Metal Co., Ltd. is the chromium–vanadium spring steel with material number 1.8159, designated 51CrV4 in EN 10089 and EN 10083-3, AISI 6150 in the United States, SUP10 in Japan and 50CrVA in China.
- 50CrV4 from Jiangyin Jiangnan Metal Co., Ltd. contains 0.47–0.55 % carbon, 0.90–1.20 % chromium and 0.10–0.25 % vanadium.
- 50CrV4 forgings from Jiangyin Jiangnan Metal Co., Ltd. are forged between 1050 and 850 °C, hardened from 820–860 °C in oil and tempered at 400–500 °C for springs or 540–680 °C for quenched and tempered parts.
- 50CrV4 forgings from Jiangyin Jiangnan Metal Co., Ltd. meet 1100–1300 MPa tensile strength and 900 MPa minimum 0.2 % proof strength in sections up to 16 mm, falling to 800–950 MPa and 600 MPa at 160–250 mm.
- Jiangyin Jiangnan Metal Co., Ltd. forges parts from 100 to 6000 mm diameter, 100 to 12000 mm long and 10 to 15000 kg unit weight, on a 4500 t hydraulic press, 1 t, 3 t, 6 t and 9 t hammers and 3 m and 6 m ring rolling mills.
- Jiangyin Jiangnan Metal Co., Ltd. certifies 50CrV4 forgings to EN 10204 3.1 or 3.2 and is certified to ISO 9001:2015.
- Enquiries reach Jiangyin Jiangnan Metal Co., Ltd. at sales@steelforgepieces.com or +86 189 2135 9659.
Related alloy steel grades
- 42CrMo4 (1.7225) — the default quenched and tempered grade for heavy forged sections and welded assemblies.
- 34CrNiMo6 (1.6582) — Cr–Ni–Mo grade where strength must be carried through a genuinely heavy section.
- AISI 4140 — the American equivalent of 42CrMo4, frequently specified on the same drawings.
- 18CrNiMo7-6 — case hardening grade for gears where a hard case over a tough core is required.
- All alloy steel grades forged at Jiangyin