34CrMo4 (1.7220) forgings
Chromium-molybdenum alloy steel to EN 10083-3, open-die forged into rings, flanges, shafts, discs and bars from 10 kg to 15,000 kg.
- Grade designation
- 34CrMo4
- Material number
- 1.7220
- Standards
- EN 10083-3, EN 10250-3
- Nearest AISI/SAE
- 4135
- Piece weight
- 10 to 15,000 kg
- Outside diameter
- 80 to 6,000 mm
- Delivery condition
- +A, +N, +QT
- Certificate
- EN 10204 3.1 / 3.2
Summary
34CrMo4, material number 1.7220, is a chromium-molybdenum alloy steel for quenching and tempering, specified in EN 10083-3. It contains 0.30 to 0.37% C, 0.90 to 1.20% Cr and 0.15 to 0.30% Mo. Quenched and tempered, it reaches 900 to 1,100 MPa tensile strength in a 16 to 40 mm ruling section and 700 to 850 MPa at 160 to 250 mm. It is specified for parts that need high strength and fatigue resistance and that are easier to weld than the same part in 42CrMo4.
Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging factory in Jiangyin, Jiangsu Province, China, in production since 1997. We forge 34CrMo4 rings, flanges, shafts, discs, bars, sleeves and tube sheets from 10 kg to 15,000 kg, in diameters from 80 mm to 6,000 mm and lengths to 12,000 mm. Steel is melted by EAF + LF + VD. Forgings are ultrasonically tested to EN 10228-3, SEP 1921 or ASTM A388 and supplied with an EN 10204 3.1 or 3.2 certificate.
What 34CrMo4 is
34CrMo4 is a low-alloy chromium-molybdenum engineering steel supplied in the quenched and tempered condition. The designation follows EN 10027-1. The figure 34 is the mean carbon content in hundredths of a percent, so 0.34%. Cr and Mo are the main alloying elements. The final 4 is the chromium content multiplied by four, giving about 1.0% Cr. Its material number under EN 10027-2 is 1.7220.
Chromium raises hardenability and tempering resistance. Molybdenum reduces temper embrittlement and holds strength at elevated temperature. Together they give a steel that hardens through medium sections and keeps good toughness, which is why it is used for shafts, gears, rings and pressure parts that carry fatigue loads.
34CrMo4 has roughly 0.08% less carbon than 42CrMo4 (1.7225, AISI 4140) and about 100 to 150 MPa less tensile strength. The lower carbon makes it easier to weld, less prone to quench cracking and slightly tougher on impact. A good number of drawings call for 42CrMo4 out of habit when 34CrMo4 would carry the load.
Older drawings and datasheets still refer to EN 10083-1:1991. That edition has been withdrawn. Alloy quenched and tempered steels are now covered by EN 10083-3, and open-die forgings in alloy special steels by EN 10250-3. We forge and certify to either, or to ASTM, JIS, GB or GOST equivalents.
Chemical composition of 34CrMo4
The chemical composition of 34CrMo4 to EN 10083-3 is given below as percent by mass on the heat analysis. Our steel is melted by electric arc furnace, ladle refining and vacuum degassing, written EAF + LF + VD, which keeps hydrogen, oxygen and non-metallic inclusions low enough for heavy forged sections.
| Element | C | Si | Mn | P | S | Cr | Mo |
|---|---|---|---|---|---|---|---|
| Heat analysis | 0.30–0.37 | max 0.40 | 0.60–0.90 | max 0.025 | max 0.035 | 0.90–1.20 | 0.15–0.30 |
| Permissible deviation, product analysis | ±0.02 | ±0.03 | ±0.04 | +0.005 | +0.005 | ±0.05 | ±0.03 |
The free-machining variant 34CrMoS4 (1.7226) has the same composition apart from a controlled sulphur content of 0.020 to 0.040%. It machines better and has lower transverse toughness.
Mechanical properties of 34CrMo4
Mechanical properties of quenched and tempered 34CrMo4 depend on the ruling section, because the cooling rate at the test position drops as the section grows. The table gives the EN 10083-3 minimum values for the +QT condition on longitudinal test pieces.
| Property | d = 16–40 mm t = 8–20 mm |
d = 40–100 mm t = 20–60 mm |
d = 100–160 mm t = 60–100 mm |
d = 160–250 mm t = 100–160 mm |
|---|---|---|---|---|
| Yield strength Re, min (MPa) | 650 | 550 | 500 | 450 |
| Tensile strength Rm (MPa) | 900–1,100 | 800–950 | 750–900 | 700–850 |
| Elongation A, min (%) | 12 | 14 | 15 | 15 |
| Reduction of area Z, min (%) | 50 | 55 | 55 | 60 |
| Impact energy KV, min (J) | 40 | 45 | 45 | 45 |
d is the diameter of a round bar or the ruling section, t is the thickness of flat product. Sections above 250 mm are supplied to a property level agreed on the order and established by a test forging or a Jominy trial. Send the section size with your enquiry and we will confirm what is achievable before you order.
Hardness in the as-supplied condition
34CrMo4 forgings are usually delivered ready heat treated at 18 to 22 HRC, about 200 to 240 HB. At this level the material machines easily and still carries the full alloy strength. In the soft annealed condition (+A) the hardness is 229 HB maximum. Higher tempered levels of 28 to 32 HRC are available where the design calls for them.
Physical properties of 34CrMo4
| Property | Value |
|---|---|
| Density | 7.85 g/cm³ |
| Modulus of elasticity | approx. 210 GPa |
| Thermal conductivity | approx. 42 W/(m·K) |
| Specific heat capacity | approx. 460 J/(kg·K) |
| Coefficient of thermal expansion, 20 to 300 °C | approx. 12.5 × 10⁻⁶ /K |
| Transformation point Ac1 | approx. 740 °C |
| Transformation point Ac3 | approx. 800 °C |
| Martensite start Ms | approx. 350 °C |
| Carbon equivalent CEV | approx. 0.70 to 0.75 |
These are indicative values for design comparison. Where a physical property is safety critical, ask for it to be measured and reported on the certificate.
34CrMo4 equivalent grades
The grades below are the closest international equivalents to 34CrMo4. They match on nominal chemistry. They do not necessarily match on delivery condition, testing or property class, so treat them as cross-references rather than drop-in substitutions.
| Standard or country | Designation | Note |
|---|---|---|
| EN 10083-3, Europe | 34CrMo4 / 1.7220 | Reference grade |
| EN, free-machining | 34CrMoS4 / 1.7226 | S 0.020 to 0.040% |
| ISO 683-2 | 34CrMo4 | Identical designation |
| ASTM / SAE, USA | 4135, also 4137 | Nearest carbon match. 4140 is 42CrMo4 |
| JIS G4105, Japan | SCM435 | C 0.33 to 0.38% |
| GB/T 3077, China | 35CrMo | Widely used equivalent |
| GOST 4543, Russia | 35KhM | Close match |
| AFNOR, France | 35CD4 | Close match |
| UNI, Italy | 35CrMo4 | Close match |
| BS 970, UK | 708A37 | Close match |
| SS, Sweden | 2234 | Close match |
If your drawing calls out one of these grades, quote it as written on the enquiry. We forge to the standard stated on the order and certify against it, rather than substituting an equivalent.
34CrMo4 against 42CrMo4 and 25CrMo4
These three grades use the same chromium-molybdenum system and differ mainly in carbon, which sets the strength ceiling and the ease of welding. This is the comparison buyers ask about most often.
| Item | 25CrMo4 (1.7218) | 34CrMo4 (1.7220) | 42CrMo4 (1.7225) |
|---|---|---|---|
| Carbon | 0.22–0.29% | 0.30–0.37% | 0.38–0.45% |
| Rm at 100–160 mm (+QT) | approx. 700–850 MPa | 750–900 MPa | approx. 850–1,000 MPa |
| Hardenability in heavy sections | Moderate | Good | Best of the three |
| Weldability | Best of the three | Good, with preheat | Most demanding |
| Nearest AISI/SAE | 4130 | 4135 | 4140 |
| Typical use | Welded pressure parts, tubing | Shafts, rings, gears, valve parts | Heavy shafts, high-strength bolting |
As a rough guide, use 42CrMo4 where the section is heavy and strength governs, 34CrMo4 where the part is welded or fatigue governs, and 25CrMo4 where weldability comes first. We forge all three, so changing grade at the enquiry stage costs nothing.
Heat treatment and forging data for 34CrMo4
34CrMo4 forgings can be supplied annealed (+A), normalised (+N) or quenched and tempered (+QT) according to the drawing. The parameters below are the working ranges used in our heat treatment shop.
| Operation | Temperature | Cooling and notes |
|---|---|---|
| Forging | 1,100 to 1,200 °C start, finish above 850 °C | Slow cool in still air or in the furnace. Heavy sections are furnace cooled to avoid flaking |
| Normalising (+N) | 850 to 890 °C | Air cool |
| Soft annealing (+A) | 680 to 720 °C | Furnace cool. Hardness 229 HB maximum |
| Hardening | 830 to 870 °C | Oil quench. Water quench for small sections |
| Tempering | 540 to 680 °C | Air cool. Temperature selected to reach the specified strength class |
| Stress relieving | 550 to 650 °C | Slow cool in the furnace, below the tempering temperature |
Welding 34CrMo4
The carbon equivalent of 34CrMo4 is about 0.70 to 0.75, so it is weldable but needs care. Use low-hydrogen consumables, preheat to 200 to 300 °C and hold the interpass temperature. Post-weld heat treatment at 600 to 680 °C is normal, kept below the tempering temperature of the parent forging so the heat treated condition is not disturbed. Welding on a quenched and tempered part should be agreed with the design authority first.
Machining
Machinability is best in the annealed condition. Quenched and tempered material at 18 to 22 HRC machines predictably with carbide tooling. Where chip control on automatic machines matters more than transverse toughness, specify 34CrMoS4 (1.7226).
34CrMo4 forgings we manufacture
Every 34CrMo4 part below is made to customer drawing by open-die forging or seamless ring rolling. No dies are cut, so single prototypes and small batches are as practical as series work.
| Product form | Size range | Typical use |
|---|---|---|
| Seamless rolled rings | OD 300 to 6,000 mm | Slewing rings, gear blanks, bearing races |
| Forged rings | OD 80 to 6,000 mm | Spacers, retaining rings, housings |
| Forged flanges | OD to 6,000 mm | Pressure vessels, pipelines, heat exchangers |
| Forged shafts and spindles | Length to 12,000 mm | Pumps, compressors, gearboxes, turbines |
| Forged discs and blocks | Diameter 80 to 6,000 mm | Valve bodies, Y-blocks, tooling blanks |
| Forged round and flat bars | Diameter 80 to 1,200 mm | Machining stock, pins, tie rods |
| Forged tube sheets | Diameter to 6,000 mm | Shell and tube heat exchangers |
| Forged pipes, sleeves and bushings | OD 80 to 2,500 mm | Cylinders, liners, hydraulic bodies |
| Forged gear blanks | Diameter to 4,000 mm | Power transmission, mill drives |
| Forged valve parts | 10 to 15,000 kg | Bodies, bonnets, stems, seat rings |
Maximum piece weight is 15,000 kg across all forms. Parts are supplied as-forged, with machining allowance, rough machined or finish machined to drawing.
How a 34CrMo4 forging is made here
This is the route a 34CrMo4 order follows at our Jiangyin works, from melt to packing.
- Melting, EAF + LF + VD Electric arc melting, ladle refining for composition and inclusion control, then vacuum degassing to lower hydrogen and reduce the risk of flaking in heavy sections.
- Ingot and billet preparation Ingots are cropped top and bottom to remove shrinkage and segregation before forging.
- Open-die forging Forged on 1 t, 3 t, 5 t and 9 t hammers and a 4,500-ton hydraulic press. Upsetting and drawing passes are planned to give a forging ratio that closes porosity and orients grain flow along the load path.
- Ring rolling Rings are pierced and rolled on seamless ring rolling mills up to 6 m diameter. This gives a continuous circumferential grain flow that a ring cut from plate does not have.
- Heat treatment Annealing, normalising, or quenching and tempering to the specified condition, with charted furnace cycles.
- Machining Rough or finish machining to drawing: boring, facing, turning, drilling.
- Testing and certification Chemical analysis, mechanical testing, hardness, ultrasonic examination, then the EN 10204 3.1 or 3.2 document set, marking and packing for sea or air freight.
Testing, inspection and certification
34CrMo4 forgings are ultrasonically tested to EN 10228-3, SEP 1921 or ASTM A388, to the quality class stated on the order. Material certificates are issued to EN 10204 3.1 by our own inspection department, or to EN 10204 3.2 countersigned by a third-party surveyor.
- Ladle and product chemical analysis by spectrometer
- Tensile, yield, elongation and reduction of area
- Charpy V-notch impact, including sub-zero temperatures
- Brinell and Rockwell hardness surveys
- Ultrasonic testing to EN 10228-3, SEP 1921 or ASTM A388
- Magnetic particle and dye penetrant examination
- Grain size, macro-etch and inclusion rating
- Dimensional inspection report against drawing
Third-party inspection by BV, DNV, LR, CCS or NK can be arranged, and customer or end-user witness inspection is welcome at any hold point.
Where 34CrMo4 forgings are used
34CrMo4 covers the strength range that most rotating and pressure-containing machinery needs, so it is one of the most commonly specified forging grades in these sectors.
- Oil and gas. Wellhead components, Christmas trees, BOP parts, spools, riser components, manifolds, Y-blocks
- Valves. Bodies, bonnets, stems and seat rings for ball, gate, globe, check and plug valves
- Pressure equipment. Vessel flanges, nozzles, tube sheets, air receivers, shell and tube heat exchangers, columns and towers
- Power transmission. Gear blanks, pinion shafts, couplings, gearbox and turbine components
- Pumps and compressors. Plunger and chemical pump shafts, industrial air compressor parts, nitrogen generator components
- Heavy machinery. Crankshafts and eccentric shafts for cement, sugar and concrete mills and mixers
- Shipbuilding and offshore. Subsea and deepwater production hardware, deck machinery, crane wheels
- Process industry. Reactors, crystallisers, dryers, paper and pulp rolls, pharmaceutical and biochemical equipment
About the manufacturer
Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging factory at No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China. In production since 1997, it forges carbon steel, alloy steel, tool steel, stainless steel and nickel alloys, and has exported forgings and seamless rolled rings to customers in Europe, North America, the Middle East and Asia.
| Item | Detail |
|---|---|
| In production since | 1997 |
| Location | Zhouzhuang Town, Jiangyin, Jiangsu Province, China |
| Workforce | 460 employees, including 9 senior engineers, 32 intermediate engineers and 140 technicians |
| Forging equipment | 1 t, 3 t, 5 t and 9 t open-die hammers, 4,500-ton hydraulic press, seamless ring rolling mills to 6 m |
| Melting | EAF + LF + VD. ESR and VIM + ESR + VAR for special alloys |
| Size capability | 10 to 15,000 kg per piece, diameter 80 to 6,000 mm, length to 12,000 mm |
| Approvals | CCS, BV, DNV, LR, NK |
| Certification | EN 10204 3.1 and 3.2 material certificates |
How to request a 34CrMo4 quotation
Send a drawing and we will normally return a price, forged weight and lead time within one working day. Include as much of the following as you have.
- Drawing or dimensions A 2D drawing, 3D model, or the rough forging dimensions: OD, ID, height, length.
- Grade and standard 34CrMo4 or 1.7220, and the governing standard: EN 10083-3, EN 10250-3, or a customer specification.
- Delivery condition As-forged, annealed, normalised, or quenched and tempered to a stated strength or hardness class.
- Machining and testing Machining allowance or finish machining, ultrasonic class, hardness, impact temperature, grain size.
- Quantity, certificate and destination Piece quantity, EN 10204 3.1 or 3.2, and the destination port.
Contact Jiangyin Jiangnan Metal
Jiangyin Jiangnan Metal Co., Ltd., open-die forging factoryNo.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China
Phone and WhatsApp: +86 189 2135 9659
Email: sales@steelforgepieces.com
Questions we are asked about 34CrMo4
What is 34CrMo4 steel?
34CrMo4 is a chromium-molybdenum alloy steel for quenching and tempering, specified in EN 10083-3 under material number 1.7220. It contains about 0.34% carbon, 0.90 to 1.20% chromium and 0.15 to 0.30% molybdenum, and is used for shafts, rings, flanges, gears and pressure-containing parts that need high strength with good toughness.
What is the material number of 34CrMo4?
The EN material number of 34CrMo4 is 1.7220. The sulphur-treated free-machining version, 34CrMoS4, carries material number 1.7226.
Is 34CrMo4 the same as AISI 4140?
No. AISI 4140 corresponds to 42CrMo4 (1.7225), which has a higher carbon content of 0.38 to 0.45%. The nearest AISI or SAE grade to 34CrMo4 is 4135, with 4137 also close. AISI 4130 has lower carbon and is closer to 25CrMo4.
What is the difference between 34CrMo4 and 42CrMo4?
Both grades have the same chromium and molybdenum content. The difference is carbon: 34CrMo4 has 0.30 to 0.37% C, 42CrMo4 has 0.38 to 0.45% C. 42CrMo4 reaches higher strength and hardenability in heavy sections, while 34CrMo4 is easier to weld and slightly tougher at a lower strength level. For a 100 to 160 mm ruling section, quenched and tempered 34CrMo4 gives 750 to 900 MPa tensile strength against roughly 850 to 1,000 MPa for 42CrMo4.
Can 34CrMo4 be welded?
Yes, but it needs care. The carbon equivalent is about 0.70 to 0.75, so preheat of 200 to 300 °C, low-hydrogen consumables and post-weld heat treatment at 600 to 680 °C are normally required. Welding is easier than on 42CrMo4 because the carbon content is lower.
What hardness does 34CrMo4 reach?
Quenched and tempered 34CrMo4 forgings are usually supplied at 18 to 22 HRC, about 200 to 240 HB, for large sections. Higher tempered levels of 28 to 32 HRC can be supplied on request. Soft annealed hardness is 229 HB maximum, and as-quenched untempered martensite reaches about 50 HRC.
What size 34CrMo4 forgings can you supply?
Jiangyin Jiangnan Metal Co., Ltd. forges 34CrMo4 parts from 10 kg to 15,000 kg, in outside diameters from 80 mm to 6,000 mm and lengths up to 12,000 mm, using open-die hammers, a hydraulic press and seamless ring rolling mills.
Which certificates are supplied with 34CrMo4 forgings?
Material certificates are issued to EN 10204 3.1 by our own inspection department, or EN 10204 3.2 countersigned by a third party such as BV, DNV, LR, CCS or NK. Ultrasonic testing reports follow EN 10228-3, SEP 1921 or ASTM A388.
Is there a minimum order quantity for 34CrMo4 forgings?
Open-die forging needs no dedicated dies, so single prototype pieces and small batches are practical as well as series production. The economical minimum depends on piece weight and heat treatment batch size, and is confirmed on quotation.
Can 34CrMo4 forgings be supplied machined?
Yes. Forgings can be delivered black, meaning as-forged, or with machining allowance, rough machined, or finish machined to drawing, including bored rings, stepped shafts and drilled flanges.
Standards referenced on this page
- EN 10083-3. Steels for quenching and tempering: technical delivery conditions for alloy steels. Composition and mechanical properties of 34CrMo4.
- EN 10250-3. Open die steel forgings for general engineering purposes: alloy special steels.
- EN 10027-1 and EN 10027-2. Designation systems for steels: names and material numbers.
- ISO 683-2. Heat-treatable steels, alloy steels and free-cutting steels.
- EN 10228-3. Non-destructive testing of steel forgings: ultrasonic testing of ferritic or martensitic steel forgings.
- SEP 1921. Ultrasonic testing of steel forgings.
- ASTM A388/A388M. Standard practice for ultrasonic examination of steel forgings.
- EN 10204. Metallic products: types of inspection documents, 3.1 and 3.2 certificates.
Technical data on this page comes from the standards listed above and from our own works practice. Reviewed by the technical department of Jiangyin Jiangnan Metal Co., Ltd. Last updated 10 September 2026. Standards are revised from time to time. Check the current edition and the values that apply to your section size before releasing a design.