UNS G41500 (AISI 4150) Alloy Steel Forgings
Technical data and supply information for UNS G41500 chromium–molybdenum steel: chemical composition, physical and mechanical properties, heat treatment, forging parameters and international equivalents. Published by Jiangyin Jiangnan Metal Co., Ltd., an open-die forging works in Jiangyin, Jiangsu Province, China.
Grade overview
UNS G41500 is the Unified Numbering System designation for AISI/SAE 4150, a medium-carbon chromium–molybdenum through-hardening alloy steel with nominally 0.50 % carbon, 0.95 % chromium and 0.20 % molybdenum. It is the higher-carbon counterpart of AISI 4140. The extra 0.10 % carbon takes attainable hardness to roughly 57–60 HRC as-quenched, and costs some toughness and weldability. Material is normally supplied annealed at about 197 HB, then oil quenched from about 830 °C and tempered to a specified hardness somewhere between 530 HB (205 °C temper) and 290 HB (650 °C temper).
Jiangyin Jiangnan Metal Co., Ltd. (No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China) produces UNS G41500 as open-die forged bars, seamless rolled rings, blocks and discs, hollow sleeves and gear shafts. Enquiries: sales@steelforgepieces.com · 0086-189-2135-9659.
- UNS number
- G41500
- AISI / SAE
- 4150
- EN equivalent
- 50CrMo4 / 1.7228
- Steel type
- Cr–Mo alloy, through-hardening
- Density
- 7.85 g/cm³
- Annealed hardness
- ≈ 197 HB
- Forging range
- 1050–1200 °C
- Process
- Open-die forging & ring rolling
What is UNS G41500 steel?
UNS G41500 belongs to the 41xx family of chromium–molybdenum low-alloy steels. Chromium provides hardenability and wear resistance. Molybdenum holds back temper embrittlement and keeps strength at moderately elevated temperature. At about 0.50 % carbon the grade counts as a medium-carbon through-hardening steel, so it develops its properties by quenching and tempering right through the section rather than by case hardening.
The grade is covered by ASTM A29/A29M (general requirements for hot-wrought steel bars) and ASTM A322 (alloy steel bars of standard grades), with composition limits set by SAE J404. The variant 4150H (UNS H41500) has the same chemistry but is supplied to guaranteed hardenability bands rather than to composition limits alone.
Buyers specify 4150 instead of 4140 when a part has to hold a higher hardness in service, typically die blocks, sprockets, heavy gearing and drill collars, and when the section is thick enough to need a deeper-hardening grade. Higher carbon also makes the steel less forgiving in welding and under shock loading, so it is usually ordered quenched and tempered against a hardness band rather than against a tensile minimum on its own.
Chemical composition of UNS G41500
The table below gives the chemical composition limits for UNS G41500 / AISI 4150 alloy steel in weight per cent. Sulfur and phosphorus are maximum values, and iron is the balance.
| Element | Content (%) | Role in the alloy |
|---|---|---|
| Carbon, C | 0.48 – 0.53 | Sets attainable hardness and strength |
| Chromium, Cr | 0.80 – 1.10 | Hardenability, wear resistance |
| Manganese, Mn | 0.75 – 1.00 | Hardenability, deoxidation |
| Molybdenum, Mo | 0.15 – 0.25 | Resists temper embrittlement, hot strength |
| Silicon, Si | 0.15 – 0.35 | Deoxidiser, raises yield strength |
| Sulfur, S | 0.040 max | Residual, controlled for cleanliness |
| Phosphorus, P | 0.035 max | Residual, controlled for toughness |
| Iron, Fe | Balance | Approximately 96.7 – 97.7 % |
Composition limits per SAE J404 / ASTM A29. Some datasheets quote silicon as 0.15–0.30 %; 0.15–0.35 % is the SAE J404 convention for the 41xx series. The heat analysis on the mill test certificate governs for any given order.
Physical properties
| Property | Metric | Imperial |
|---|---|---|
| Density | 7.85 g/cm³ | 0.284 lb/in³ |
| Melting point (approx.) | 1427 °C | 2600 °F |
| Elastic (Young's) modulus | 190 – 210 GPa | 27,557 – 30,458 ksi |
| Bulk modulus (typical for steel) | 140 GPa | 20,300 ksi |
| Shear modulus (typical for steel) | 80 GPa | 11,600 ksi |
| Poisson's ratio | 0.27 – 0.30 | 0.27 – 0.30 |
Mechanical properties of UNS G41500
Annealed condition, as normally supplied for machining
| Property | Metric | Imperial |
|---|---|---|
| Tensile strength | 731 MPa | 106,000 psi |
| Yield strength | 380 MPa | 55,100 psi |
| Elongation at break (in 50 mm) | 20.2 % | 20.2 % |
| Reduction of area | 40 % | 40 % |
| Izod impact | 24 J | 17.7 ft·lb |
| Hardness, Brinell | 197 HB | 197 HB |
| Hardness, Vickers (converted) | 207 HV | 207 HV |
| Hardness, Knoop (converted) | 219 HK | 219 HK |
| Hardness, Rockwell B (converted) | 92 HRB | 92 HRB |
| Machinability (AISI 1212 = 100) | 55 % | 55 % |
Quenched and tempered, published hardness series
Table 4 gives the published tempering response of oil-quenched, fine-grained UNS G41500. These are the figures used to set a hardness band at enquiry stage, before a section size is fixed. The indicative tensile column is calculated from hardness using the conventional relationship for quenched-and-tempered steels (tensile ≈ 3.4–3.5 × HB), so treat it as a cross-check on the specification and confirm the real figure by tensile test.
| Tempering temperature | Hardness (published) | Indicative tensile (calculated) | Typical use of this condition |
|---|---|---|---|
| As-quenched | ≈ 57–60 HRC | – | Not used in service, must be tempered |
| 205 °C / 400 °F | 530 HB | ≈ 1800–1850 MPa | Maximum hardness, wear surfaces, low toughness |
| 315 °C / 600 °F | 495 HB | ≈ 1680–1730 MPa | High hardness, inside embrittlement range |
| 425 °C / 800 °F | 440 HB | ≈ 1500–1540 MPa | High strength, inside embrittlement range |
| 540 °C / 1000 °F | 370 HB | ≈ 1260–1300 MPa | Common Q+T condition for shafts and gearing |
| 650 °C / 1200 °F | 290 HB | ≈ 990–1020 MPa | Tough Q+T condition, best ductility |
Hardness values are published data for oil-quenched fine-grained 4150. The tensile column is calculated from them, not measured. Elongation and reduction of area improve as tempering temperature rises and hardness falls, but the actual values depend on section size, quench severity and grain size, so we do not publish a single figure for them. Core properties fall away as section size increases. On heavy forgings the properties are verified on a prolongation test piece and reported on the mill certificate. Send us the hardness band or tensile class you need and we will confirm what is achievable at your section size and quote the tested values.
Forging and heat treatment of UNS G41500
| Operation | Temperature | Cooling and notes |
|---|---|---|
| Open-die forging | 1050 – 1200 °C | Finish above 850 °C, cool slowly in still air or furnace |
| Normalising | 850 – 880 °C | Air cool, refines forged grain structure |
| Full annealing (supercritical) | 800 – 850 °C | Furnace cool at 20 °C/h or less to 600 °C, gives about 197 HB |
| Soft annealing (subcritical) | 680 – 720 °C | Separate operation, softens without re-austenitising |
| Hardening (austenitising) | 830 – 860 °C (830 °C typical) | Oil quench, about 57–60 HRC as-quenched |
| Tempering | 540 – 680 °C where toughness is specified | Temper immediately after quenching, air cool. Lower tempers down to 205 °C are used only for maximum hardness |
| Stress relieving | 550 – 660 °C | At least 30 °C below the last tempering temperature, slow cool |
Temper embrittlement. Like other Cr–Mo steels, UNS G41500 can lose notch toughness if it is held in, or cooled slowly through, roughly 375–575 °C. The 315 °C and 425 °C tempers in Table 4 fall inside that range, which is why they are specified only where hardness matters more than impact toughness. Where impact values are specified, temper above the band at 540–680 °C and cool quickly through it afterwards. Molybdenum is in the alloy to reduce this sensitivity.
Heavy sections. Hardenability is good but not unlimited. On large open-die forgings the surface transforms faster than the core, so quench medium, agitation and ruling section all have to be agreed against the specified hardness band. We size the forging to leave enough test and machining allowance before heat treatment.
UNS G41500 equivalent grades
The cross-reference below lists the nearest international designations for UNS G41500 / AISI 4150.
| Standard / country | Designation | Match |
|---|---|---|
| UNS (USA) | G41500 | Same grade |
| AISI / SAE (USA) | 4150 | Same grade |
| ASTM A29 / A322 (USA) | 4150 | Same grade |
| SAE J404 hardenability grade | 4150H (UNS H41500) | Same chemistry, H-band guaranteed |
| EN 10083-3 (Europe) | 50CrMo4, 1.7228 | Nearest equivalent |
| DIN (Germany, former) | 50CrMo4 | Nearest equivalent |
| AFNOR (France) | 50CD4 | Nearest equivalent |
| BS 970 (UK) | 708M50 | Nearest equivalent |
| JIS (Japan) | SCM445 | Approximate only |
| GB/T 3077 (China) | 50CrMo / 50CrMoA | Approximate only |
Important: a cross-reference points to the nearest available grade, not to an automatic substitute. Composition ranges, test requirements and acceptance criteria differ between standards. Note also that BS 970 708A42 and 708M40 are the 0.40 % C grades and cross-reference to AISI 4140; the 0.50 % C BS grade is 708M50. Verify against the governing specification and obtain written approval before substituting a grade.
UNS G41500 against AISI 4140: which should you specify?
| Criterion | AISI 4150 / UNS G41500 | AISI 4140 |
|---|---|---|
| Carbon content | 0.48 – 0.53 % | 0.38 – 0.43 % |
| As-quenched hardness | ≈ 57 – 60 HRC | ≈ 54 – 58 HRC |
| Hardness after 540 °C temper | ≈ 370 HB | ≈ 340 HB |
| Attainable tempered strength | Higher | Lower |
| Impact toughness | Lower | Higher |
| Weldability | Poor (CE ≈ 0.88) | Limited, but easier (CE ≈ 0.80) |
| Usual choice when | Wear resistance and hardness come first | Toughness and fabrication come first |
We forge both grades here, so if the specification is still open we can quote AISI 4140, 42CrMo4 and UNS G41500 side by side.
Applications of UNS G41500 forgings
Power transmission
- Gear blanks, ring gears and gear wheels
- Pinion shafts, drive shafts and spindles
- Sprockets, couplings and shaft collars
Oil, gas and drilling
- Drill collars and tool joints
- Valve bodies and pressure housings
- Pump shafts and sleeves
Heavy machinery
- Crankshafts and axles
- Hydraulic cylinder rods and pistons
- Mill rolls and roller shafts
Tooling and dies
- Forging die blocks and bolsters
- Wear plates and guide blocks
- Press components
UNS G41500 forged product forms we supply
Jiangyin Jiangnan Metal Co., Ltd. produces UNS G41500 by open-die forging and seamless ring rolling. All sizes are made to order against your drawing or specification.
| Forged form | Typical size range | Also known as |
|---|---|---|
| Round bars and rods | Ø 80 – 1200 mm | Forged shafting, billets |
| Square, rectangular, flat and hex bars | Thickness 60 – 800 mm | Forged flats, blooms |
| Hollow bars and sleeves | OD 200 – 2000 mm | Bushings, cylinders, shells, casings, housings, hubs |
| Seamless rolled rings | OD 300 – 4000 mm | Forged rings, rolled rings, flange rings |
| Blocks, discs and plates | Up to 2000 mm across | Die blocks, forged discs, forged plates |
| Gear shafts, pinion shafts and spindles | Length up to 8000 mm | Stepped shafts, ring gear blanks |
Indicative ranges only. Please send your drawing for confirmation of the exact size, single-piece weight and delivery condition.
Delivery conditions available
- As forged, with machining allowance, for customers doing their own heat treatment.
- Normalised or normalised and tempered, for stable machining.
- Annealed, approximately 197 HB, best machinability.
- Quenched and tempered (Q+T), to an agreed hardness band or tensile class.
- Rough machined or proof machined, turned, bored or milled to your dimensions.
Testing and documentation
- Chemical analysis (ladle and, on request, product analysis)
- Mechanical testing: tensile, yield, elongation, reduction of area, Charpy V-notch impact at specified temperature
- Hardness survey (Brinell or Rockwell)
- Non-destructive testing: ultrasonic (UT), magnetic particle (MT), dye penetrant (PT)
- Grain size, macro- and micro-structure examination on request
- EN 10204 3.1 mill test certificate supplied as standard, 3.2 third-party certification on request
Request a quotation for UNS G41500 forgings
Send your drawing, specification or a simple size list. Please include grade, forged form, dimensions with tolerances, single-piece weight, quantity, delivery condition (as forged, normalised, annealed or Q+T), required hardness or tensile class, testing and certification.
Frequently asked questions about UNS G41500
What is UNS G41500?
UNS G41500 is the Unified Numbering System designation for AISI/SAE 4150, a medium-carbon chromium–molybdenum through-hardening alloy steel with nominally 0.50 % carbon, 0.95 % chromium and 0.20 % molybdenum. It is supplied annealed at about 197 HB, and after forging it is normally oil quenched from about 830 °C and tempered to the required hardness.
Is UNS G41500 the same as AISI 4150?
Yes. UNS G41500 and AISI 4150 (also written SAE 4150) are two designations for the same steel. UNS G41500 is the five-digit Unified Numbering System code, and AISI/SAE 4150 is the older four-digit designation. Both are covered by ASTM A29/A29M and ASTM A322, with composition limits from SAE J404.
What is the difference between AISI 4140 and AISI 4150?
The two share the same chromium–molybdenum base, but 4150 carries about 0.50 % carbon against roughly 0.40 % in 4140. The extra carbon takes as-quenched hardness to about 57–60 HRC against 54–58 HRC for 4140, and gives higher hardness at every tempering temperature, about 370 HB against 340 HB after a 540 °C temper. The price is impact toughness, ductility and weldability. Specify 4150 where wear resistance and hardness come first, and 4140 where toughness and fabrication come first.
What is the European equivalent of UNS G41500?
The closest European equivalent is 50CrMo4, material number 1.7228, specified in EN 10083-3. The French AFNOR designation is 50CD4 and the British BS 970 designation is 708M50. These are nearest equivalents rather than exact substitutes, so check composition and property limits against the governing specification before you substitute.
What hardness can UNS G41500 reach?
Annealed, it is supplied at approximately 197 HB. Oil quenched from about 830 °C it reaches roughly 57–60 HRC as-quenched, and about 62 HRC is the maximum attainable at this carbon level. Published tempering response for oil-quenched fine-grained 4150 is 530 HB at 205 °C, 495 HB at 315 °C, 440 HB at 425 °C, 370 HB at 540 °C and 290 HB at 650 °C. Section size has a strong effect on what is achievable at the core of a heavy forging.
Can UNS G41500 be welded?
It is difficult to weld. The carbon equivalent CE(IIW) is about 0.88 at nominal composition and runs from roughly 0.80 to 0.97 across the specification limits, well above the 0.60 mark at which preheat becomes necessary. The grade is therefore prone to hydrogen cracking and to a hard, brittle heat-affected zone. Weld only in the annealed condition, with low-hydrogen consumables, preheat of roughly 300–400 °C, controlled interpass temperature, and a post-weld heat treatment below the last tempering temperature. Welding quenched-and-tempered 4150 is not recommended for load-bearing joints.
What is the forging temperature for UNS G41500?
Heat uniformly to 1050–1200 °C and keep the finishing temperature above about 850 °C. Cool slowly after forging, then normalise or anneal to refine the grain and relieve stress before machining or final quenching and tempering.
Is UNS G41500 a through-hardening or a case-hardening steel?
It is a through-hardening steel. It develops strength by quenching and tempering the whole section rather than by carburising a surface case. Where a hard surface on a tough core is wanted as well, 4150 is often induction hardened or nitrided after quenching and tempering.
What is UNS G41500 used for?
UNS G41500 is used for heavily loaded, wear-resistant machine parts: gears and gear blanks, pinion and drive shafts, spindles, axles, crankshafts, sprockets, forging and die blocks, drill collars and tool joints, hydraulic cylinder rods, pump shafts and mill rolls.
What UNS G41500 forgings can Jiangyin Jiangnan Metal supply?
Jiangyin Jiangnan Metal Co., Ltd., an open-die forging factory at No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China, supplies UNS G41500 as forged round, square, rectangular, flat and hex bars, hollow bars, sleeves, bushings, cylinders, shells and housings, seamless rolled rings, blocks, discs and plates, and gear shafts, pinion shafts, spindles, ring gears and gear wheels. Delivery conditions are as forged, normalised, annealed, quenched and tempered, or rough machined. Contact sales@steelforgepieces.com or 0086-189-2135-9659.
About the manufacturer
Jiangyin Jiangnan Metal Co., Ltd.
Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging factory in Jiangyin, Jiangsu Province, inside the Yangtze River Delta manufacturing belt and close to the ports of Shanghai and Ningbo. The works produces forged bars, seamless rolled rings, blocks and discs, hollow sleeves and shafts in carbon steel, alloy steel, tool steel, stainless steel and nickel alloys, supplied worldwide against customer drawings and international specifications.
Address: No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China
Telephone: 0086-189-2135-9659
Email: sales@steelforgepieces.com
Website: www.steelforgepieces.com
Page last reviewed by the technical sales team at Jiangyin Jiangnan Metal Co., Ltd.
Related alloy steel grades
We forge the full chromium–molybdenum family. Compare UNS G41500 with its neighbours:
- AISI 4140 forgings
- AISI 4140H forgings
- AISI 4130 forgings
- 42CrMo4 forgings
- 42CrMo4V forgings
- 42CrMoS4 forgings
- 1.7225 forgings
- 1.7227 forgings
- 34CrMo4 forgings
- 34CrMoS4 forgings
- 1.7220 forgings
- SCM440 forgings
- 42CD4 forgings
- 708M40 forgings
- 35KhM forgings
References
- SAE J404, Chemical Compositions of SAE Alloy Steels (composition limits for 4150 / UNS G41500).
- ASTM A29/A29M, Standard Specification for General Requirements for Steel Bars, Carbon and Alloy, Hot-Wrought.
- ASTM A322, Standard Specification for Steel Bars, Alloy, Standard Grades.
- EN 10083-3, Steels for quenching and tempering, alloy steels (50CrMo4 / 1.7228).
- ASM Metals Handbook, Vol. 1, Properties and Selection: Irons, Steels and High-Performance Alloys (quenched-and-tempered property data for 4150).
- EN 10204, Metallic products, types of inspection documents.