1.7225 Forgings

What is 1.7225 steel?

42CrMo4 is the reference grade of the Cr-Mo family. Chromium raises hardenability and tempering resistance. Molybdenum adds hardenability and suppresses temper embrittlement, which is what allows thick sections to be tempered between 540 and 680 °C without losing toughness. Carbon at about 0.42 % sets the hardness that can be reached. Together these give a steel that carries 900 to 1100 MPa in medium sections while keeping 12 % elongation and 35 J of Charpy energy, at a price most engineering budgets can absorb.

The difference between 1.7225 and its free-machining twin 1.7227 (42CrMoS4) is sulphur. In 1.7225 sulphur is an impurity held to 0.035 % maximum. In 1.7227 it is a deliberate addition of 0.020 to 0.040 %. Lower sulphur means fewer elongated manganese sulphide inclusions, which gives better transverse ductility, better through-thickness toughness, a cleaner surface after polishing or plating, and lower risk of hot cracking during welding. Design authorities in pressure equipment, offshore and low-temperature service normally specify 1.7225 for those reasons.

We supply 1.7225 as forged product only: open-die forgings and seamless rolled rings. Forging closes centreline porosity from the ingot and aligns grain flow with the principal stress direction, along the hoop in a rolled ring and along the axis in a shaft. A rolled ring in 1.7225 outperforms a ring flame-cut from plate of the same chemistry in fatigue life and in burst strength, and the gap widens as the section gets heavier.

1.7225 vs 1.7227: when the sulphur cap matters

Drawings often allow either grade. The two share the same chemistry envelope apart from sulphur, and EN 10083-3 lists the same mechanical minima for both. The decision is not about strength. It is about what happens to the part after forging, and how it is loaded in service.

Compiled by Jiangyin Jiangnan Metal Co., Ltd. from EN 10083-3 and normal forging-shop practice. Shaded cells mark where 1.7225 is the better choice. See also our 1.7227 forgings, 42CrMo4 and 42CrMoS4 pages.

1.7225 vs AISI 4140: the substitution buyers get wrong

42CrMo4 and AISI 4140 are treated as interchangeable in most of the world, and for general engineering they usually are. The chemistry envelopes are not identical. The mismatch sits in manganese, which is where a well-meant substitution fails a dual-certification check.

Comparison prepared by Jiangyin Jiangnan Metal Co., Ltd. from EN 10083-3 and ASTM A29 / SAE J404. Composition limits only. Both standards carry further requirements on testing, tolerance and delivery condition that are not reproduced here.

42CrMo4 permits 0.60 to 0.90 % manganese. AISI 4140 requires 0.75 to 1.00 %. A heat aimed at the middle of the 42CrMo4 range, say 0.70 % Mn, is a sound 42CrMo4 and is not 4140. Only heats aimed deliberately at the 0.75 to 0.90 % overlap satisfy both specifications at the same time. Chromium overlaps between 0.90 and 1.10 %, and carbon between 0.38 and 0.43 %.

There is a second difference, in what the two standards actually cover. EN 10083-3 mandates mechanical minima against a ruling section, as set out in Table 5. ASTM A29 is a chemistry and dimensional standard and does not mandate mechanical properties for bar. On a 4140 part the strength requirement comes from the purchaser, or from a downstream specification such as ASTM A193 or API 6A. A certificate reading 4140 therefore tells you less on its own than one reading 42CrMo4 +QT.

1.7225 equivalent grades worldwide

Buyers reach this steel through at least a dozen designations. Every entry below describes the same Cr-Mo alloy system. We accept purchase orders under any of them and issue a material test certificate listing each specification the heat satisfies.

Cross-reference held by Jiangyin Jiangnan Metal Co., Ltd., compiled from the published standards named in the table. Equivalents are guides for enquiry, not substitutions. Chemistry limits, tolerances, test frequency and acceptance criteria differ between standards, so every order should name one governing specification. For AISI 4140 in particular, see Table 2.

Chemical composition of 1.7225

The table below is the specification range we forge to, taken from EN 10083-3 for 42CrMo4. Every heat is supplied with a ladle analysis on the mill certificate. Product analysis on the finished forging can be added on request.

EN 10083-3 grade 42CrMo4, as forged by Jiangyin Jiangnan Metal Co., Ltd. Melting route: electric arc furnace, ladle furnace refining and vacuum degassing (EAF + LF + VD). Vacuum degassing is standard on our 1.7225 heats and keeps hydrogen low enough to avoid flaking in heavy sections.

Tighter limits than the standard are available where a customer specifies restricted residuals for pressure or offshore service. Common restrictions are sulphur to 0.015 % maximum and phosphorus to 0.020 % maximum, with limits on copper, nickel, tin and antimony to control temper embrittlement in heavy sections. State the limits at enquiry, since they affect which heat is bought rather than what is tested afterwards.

Mechanical properties of 1.7225 in the +QT condition

Alloy steel properties fall as section size grows, because the quench cannot cool the core as fast as the surface. EN 10083-3 specifies minima against a ruling section for that reason. The values below are what we certify on 1.7225 forgings in the quenched and tempered condition. Results on the mill certificate normally sit above these minima.

EN 10083-3 mechanical property table for 42CrMo4 in the +QT condition, as certified by Jiangyin Jiangnan Metal Co., Ltd. Tensile testing to ISO 6892-1 or ASTM E8. Charpy V-notch, longitudinal, to ISO 148-1 or ASTM E23. Above 250 mm ruling section, properties are agreed at enquiry and demonstrated on a test prolongation from the same heat and the same heat-treatment charge. For open-die forgings the parallel standard is EN 10250-3.

Two things follow from this table. On a large ring or a heavy shaft, do not quote the small-section numbers on the drawing; specify the ruling section and the test position, or the certificate and the design assumption will not match. Second, oil quenching through-hardens 1.7225 fully only to about 60 mm diameter. Above that the core is a mixed structure and core properties fall away, which is what the table describes. Where a heavy section needs higher core strength, 34CrNiMo6 is the usual alternative.

Hardness and delivery conditions

We deliver 1.7225 forgings in whichever condition the drawing calls for. State the target hardness band and the test location. On rings and discs, hardness is normally taken at mid-wall on a machined face after the final temper.

Jiangyin Jiangnan Metal Co., Ltd. delivery practice. Hardness conversions between HBW, HRC and HV are approximate and follow ISO 18265. The certificate reports the scale actually measured, not a conversion. EN 10083-3 caps 42CrMo4 in the soft annealed condition at 241 HBW.

Physical and thermal properties

Consolidated by Jiangyin Jiangnan Metal Co., Ltd. from published 42CrMo4 datasheets. Physical properties are not certified values and vary a few per cent with heat treatment and temperature. CEV calculated as C + Mn/6 + (Cr + Mo + V)/5 + (Ni + Cu)/15 on mid-range chemistry. The service-temperature ceiling is a practical limit: above roughly 400 °C the steel continues to temper in service and strength decays.

Heat treatment of 1.7225 forgings

The cycles below are run in calibrated furnaces with recorded time and temperature charts for the whole load, and every chart is issued with the mill certificate. If your specification prescribes different temperatures or soak times, send it with the enquiry. Heat treatment drives both lead time and price on this grade.

Heat-treatment practice for 42CrMo4 at Jiangyin Jiangnan Metal Co., Ltd., consistent with EN 10083-3. Temper below 540 °C only where the specification requires it. The 250 to 450 °C range is avoided because of tempered-martensite embrittlement.

Choosing a tempering temperature

Tempering temperature is the single lever that sets delivered hardness. As a working guide on medium sections: temper near 540 °C for the 300 to 330 HBW band, near 600 °C for 270 to 300 HBW, and near 660 to 680 °C for the 197 to 235 HBW band used in sour service. Confirm on a test piece from the same heat and charge, because section size shifts the response.

Temper embrittlement in heavy sections

42CrMo4 is susceptible to reversible temper embrittlement if it is held in, or cooled slowly through, roughly 375 to 575 °C. Molybdenum suppresses the mechanism, which is why the grade carries 0.15 to 0.30 % Mo, but on heavy forgings the risk is still real. Our practice is to cool briskly through the range after tempering rather than furnace-cool, and to control the residual elements that drive it: phosphorus, tin, antimony and arsenic. Where a specification sets a J-factor or X-bar limit on residuals, tell us at enquiry so the heat can be selected against it.

Welding, machining and surface treatment

Welding

Of the two 42CrMo grades, 1.7225 is the one to weld. The carbon equivalent is still around 0.80 and the steel is classed as difficult to weld, but without the deliberate sulphur addition of 1.7227 the hot-cracking mechanism is absent and only hardenability has to be managed.

A workable procedure preheats to 250 to 350 °C depending on section and restraint, holds interpass temperature so the joint never falls below preheat between passes, uses baked low-hydrogen consumables or a low-hydrogen process, and post-weld heat treats at 600 to 680 °C, at least 30 °C below the original tempering temperature so the parent metal keeps its certified properties. Never weld a part in the as-quenched condition, and do not skip PWHT on a pressure-retaining or fatigue-loaded joint.

Machining

Machine 1.7225 in the annealed condition at 241 HBW maximum, or in the tempered condition up to about 300 HBW. Without free-machining sulphides the chips are stringier at low feed, and tool life is the baseline against which 1.7227 is measured, typically 10 to 25 % shorter at the same hardness and speed. Use rigid setups, coated carbide, positive-rake geometry and enough feed to keep the tool cutting rather than rubbing. Above 320 HBW tool life falls quickly and it is usually cheaper to rough machine before the final temper. Where a part is heavily machined and none of the toughness, welding or surface-finish arguments apply, 1.7227 costs less to produce.

Surface treatment

The grade takes gas and plasma nitriding well, giving a 600 to 650 HV case with very little distortion, which is why it is common on gear teeth and pump plungers. Induction and flame hardening give 53 HRC and above on journals and spline flanks, on sections up to 250 mm diameter. For plated, polished or nitrided surfaces 1.7225 is the correct grade. Sulphide inclusions in 1.7227 can open as pits at the finished surface and are a common cause of chrome-plating rejects.

Low-temperature and transverse toughness

This is the property that most often decides between 1.7225 and the alternatives, and the one most often left off the enquiry. Sulphides are plastic at rolling and forging temperature, so they stretch out into ribbons along the working direction. Loaded along that direction they do little harm. Loaded across it, through the wall of a ring, across the axis of a shaft, through the thickness of a flange, they behave as flat internal defects. Low sulphur is what keeps 1.7225 usable in those directions.

Four points worth putting on the enquiry:

• Test direction. Longitudinal Charpy values overstate what a transversely loaded part will see. If the service load is transverse or through-thickness, specify the test direction and we will forge and test accordingly.
• Sub-zero testing. Charpy V-notch at −20 °C or −40 °C can be specified on 1.7225. Achievable energy depends on ruling section, tempering temperature and test direction, so the acceptance value has to be agreed at enquiry. A heavy section tempered for high strength will not reach the same sub-zero energy as a light section tempered soft.
• Tempering trade-off. Toughness and strength move in opposite directions. Asking for the top of the strength band and high sub-zero impact energy in the same heavy section is often not achievable in 42CrMo4. That is the point at which 34CrNiMo6 or another nickel-bearing grade becomes the right answer, and we will say so.
• Through-thickness properties. For flanges and tube sheets loaded through the thickness, ask about Z-quality, meaning short transverse reduction of area. It is a melting and cleanliness requirement decided at heat selection, not something that can be added later.

1.7225 in sour service: NACE MR0175 / ISO 15156

For sour service 1.7225 is normally the better of the two 42CrMo grades. Sulphide stress cracking initiates at inclusions, and manganese sulphides are the kind of inclusion that gives it a start, so a grade with sulphur capped as an impurity is a safer basis than one with sulphur added on purpose. Many purchaser specifications for sour service impose a sulphur limit tighter than the 0.035 % of EN 10083-3, commonly 0.010 or 0.015 % maximum, together with limits on phosphorus and on inclusion rating. We can melt to those limits. State them at enquiry, because they govern heat selection.

In practice the sour-service temper and the general-engineering temper are different products from the same forging. Tell us at enquiry which one you need. We hardness-test to the mapping in the applicable specification, report every reading rather than an average, and supply NACE MR0175 / ISO 15156 documentation in the certificate pack.

How Jiangyin Jiangnan Metal forges 1.7225

The route below is what we run on every 1.7225 order. Each stage produces a record that goes into the documentation pack.

1. Melting and billet sourcingIngot or billet is bought only against documented EAF + LF + VD practice. Vacuum degassing controls hydrogen and keeps inclusion content low enough for ultrasonic acceptance on heavy sections. Where restricted residuals are specified, the heat is selected against those limits before it is bought.
2. Billet preparation and soakingSurfaces are conditioned and the billet is soaked to a uniform through-temperature before the first blow. An under-soaked Cr-Mo billet cracks on the first reduction.
3. Open-die forging, 1100 to 1200 °CForged on 1, 3, 5 and 9-tonne hammers and a 5000-tonne hydraulic press, with controlled reduction ratios and reheats. Finishing temperature is held above 850 °C so the structure stays wrought.
4. Ring rolling or upsetting to shapeSeamless rings are pierced and rolled to the finished envelope. Discs are upset and punched. Both routes give continuous grain flow, which a ring cut from plate cannot offer.
5. Post-forge cooling and normalisingSlow controlled cooling, then a normalise to refine the grain before the final quench. Heavy sections get a hydrogen-removal soak.
6. Quenching and temperingOil quench from 820 to 880 °C, temper 540 to 680 °C to the hardness band on the order, then cool briskly through the temper-embrittlement range. Furnace charts are recorded for the whole load, not a sample.
7. Rough or finish machiningSupplied as-forged, rough machined with an agreed allowance, or finish machined to drawing tolerance on our own lathes and boring mills.
8. Testing and non-destructive examinationUltrasonic testing to EN 10228-3, SEP 1921 or ASTM A388. Magnetic particle or penetrant as specified. Tensile, impact and hardness testing from a prolongation heat treated with the part, in the direction the specification requires.
9. Marking, certification and packingHard-stamped heat number and part identification, EN 10204 3.1 certificate, or 3.2 counter-signed by a third party such as TÜV, BV, SGS or Lloyd's Register, then seaworthy packing.

1.7225 forged forms and size capability

All parts are made to your drawing or dimensional sketch. There is no fixed catalogue. The range below covers what we forge regularly in 1.7225.

Forging capability for 1.7225 at Jiangyin Jiangnan Metal Co., Ltd. Delivery conditions: as-forged, normalised, annealed, quenched and tempered, rough machined or finish machined. See also our pages on forged disks, forged rolls and forged valve stems.

Where 1.7225 forgings are used

1.7225 is chosen where a part needs 900 to 1100 MPa tensile strength with real toughness, and where the load is not purely along the grain. It is the default alloy steel on drawings across pressure equipment, power transmission and offshore.

The steel is not suitable for continuous service above about 400 °C, where tempering continues in service and strength decays, nor for corrosive duty without a coating. For hot service, see our other alloy steel grades. For corrosive duty, see stainless and nickel alloy forgings. Where a part is heavily machined and none of the toughness, welding or surface arguments apply, 1.7227 is the cheaper answer.

Testing, inspection and certification

Every 1.7225 forging ships with a documentation pack. Its content is agreed before production starts, so there are no surprises at inspection.

• Chemical analysis. Ladle analysis on every heat. Product analysis on the finished forging on request.
• Mechanical testing. Tensile, 0.2 % yield, elongation, reduction of area and Charpy V-notch impact, taken from integral or separately forged prolongations heat treated with the part, in the test direction the specification requires.
• Sub-zero impact testing. Charpy V-notch at −20 °C, −40 °C or a customer temperature, with the acceptance value agreed against the ruling section at enquiry.
• Hardness. Brinell to ISO 6506 or ASTM E10, Rockwell to ASTM E18, at the locations the specification requires. All readings reported.
• Ultrasonic testing. EN 10228-3, SEP 1921 class C, D or E, ASTM A388, or a customer acceptance class.
• Surface NDT. Magnetic particle to EN 10228-1 or ASTM A275, penetrant to ASTM E165.
• Grain size and microstructure. ASTM E112 or ISO 643, with photomicrographs where specified. Inclusion rating to ASTM E45 or ISO 4967 where cleanliness is part of the specification.
• Dimensional report. Against the drawing, before shipment.
• Certification. EN 10204 3.1 as standard. 3.2 witnessed and counter-signed by TÜV, BV, SGS, Lloyd's Register or your own inspector.
• Regulatory documentation. NACE MR0175 / ISO 15156 and PED 2014/68/EU where the end use requires it.

Our in-house laboratory runs a universal testing machine, impact testing machine, hardness testers, a metallographic microscope, magnetic particle equipment and ultrasonic flaw detection. Third-party inspectors and customer QA representatives are welcome at the works, at Zhouzhuang Town, Jiangyin, roughly two hours from the port of Shanghai.

How to request a 1.7225 quotation

Send a drawing or a dimensional sketch to sales@steelforgepieces.com. Quotations are normally returned within one working day when the following points are supplied.

1. Grade and standard. 1.7225, 42CrMo4, or an equivalent designation, and which specification governs. If you need dual certification to AISI 4140, say so now. See Table 2.
2. Product form. Ring, disc, shaft, bar, flange, sleeve, block or custom shape.
3. Dimensions. OD, ID and height for rings. Diameter and length for bars and shafts. Plus an estimated finished weight.
4. Ruling section and test position. This decides which row of Table 5 applies.
5. Delivery condition. As-forged, normalised, annealed, +QT, rough machined or finish machined.
6. Hardness band. General engineering, or the sour-service band of 197 to 235 HBW.
7. Impact requirement. Test temperature, test direction and acceptance energy, if any.
8. Restricted residuals. Any sulphur, phosphorus or trace-element limits tighter than EN 10083-3.
9. Certification. EN 10204 3.1 or 3.2, and which third party if 3.2.
10. NDT requirements. UT acceptance class, MT or PT, and any special acceptance criteria.
11. Quantity and required delivery date.

Lead time for 1.7225 forgings is normally 25 to 50 days, depending on size, heat-treatment route and machining scope. There is no fixed minimum order quantity and single prototype pieces are accepted, although price per piece falls with quantity because set-up, furnace and testing charges are shared.

Email your drawing to sales@steelforgepieces.com

Frequently asked questions about 1.7225

About the manufacturer

Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging factory in Jiangyin, Jiangsu Province, China. We produce forged rings, seamless rolled rings, discs, shafts, flanges, bars, sleeves and bushings in carbon steel, alloy steel, tool steel, stainless steel and nickel-based superalloys. The works runs 1, 3, 5 and 9-tonne open-die forging hammers and a 5000-tonne hydraulic press, with ring rolling, heat treatment, machining and testing on the same site. The company employs about 460 people, including 9 senior engineers and 32 intermediate engineers. Work is made to customer drawing and certified to EN 10204 3.1 or 3.2.

• CompanyJiangyin Jiangnan Metal Co., Ltd.
• BusinessOpen-die forging, ring rolling, heat treatment, machining, testing
• AddressNo. 1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province 214423, China
• Telephone0086-189-2135-9659
• Emailsales@steelforgepieces.com
• Websitewww.steelforgepieces.com
• Quality systemISO 9001:2015; certificates to EN 10204 3.1 and 3.2
• Nearest portShanghai, approximately 2 hours by road

Related alloy steel grades we forge

• 1.7227
• 42CrMo4
• 42CrMoS4
• AISI 4140
• AISI 4140H
• SCM440
• All alloy steel grades

Other materials

• Carbon steel
• Tool steel
• Stainless steel
• 17-4PH
• 15-5PH
• PH13-8Mo
• Nickel alloy
• Inconel 718
• Inconel 625
• Hastelloy C-276

Published 20 May 2013. Last updated and reviewed 7 September 2026 by the metallurgical engineering and technical sales team, Jiangyin Jiangnan Metal Co., Ltd. Specification values are taken from the standards named against each table. Data is offered in good faith for enquiry and comparison and does not replace the full published standard or a qualified engineering assessment for a specific application.