What is AISI 4317?
AISI 4317 is a low carbon nickel chromium molybdenum case hardening steel. It is machined soft, then carburized and hardened, so the finished part carries a wear surface of roughly 58 to 62 HRC over a core that stays tough under shock and bending.
About 1.65 % chromium, 1.55 % nickel and 0.30 % molybdenum give AISI 4317 much deeper hardenability than a leaner carburizing steel such as AISI 8620. That is why it is specified for large gears, pinions and shafts, where the core has to harden right through the section.
In the annealed delivery condition AISI 4317 runs at 229 HBW maximum, about 22 HRC. At that hardness it turns, bores and gear cuts without trouble. The hardness comes later, in the carburizing furnace, so the forging is normally bought soft with a machining allowance on it.
Jiangyin Jiangnan Metal Co., Ltd. is an open die forging factory in Jiangyin, Jiangsu Province, China. We forge AISI 4317 to customer drawing rather than holding a stock list, and every piece carries its heat number through to dispatch.
Note on the AISI 4317 designation
Two different analyses are traded under the name AISI 4317. Check which one your drawing means before ordering. The chromium content differs by a factor of three.
SAE 4317 belonged to the American 43xx nickel chromium molybdenum family and is no longer an active SAE designation. Like its neighbour SAE 4320, it was a higher nickel, lower chromium steel, nominally around 1.65 to 2.00 % nickel with only 0.40 to 0.60 % chromium.
In international trade the name AISI 4317 is used differently. It has become a commercial alias for the European case hardening steel 18CrNiMo7-6, material number 1.6587, formerly designated 17CrNiMo6, which carries 1.50 to 1.80 % chromium and 1.40 to 1.70 % nickel. That cross reference appears on supplier datasheets in several countries, including the Australian grade X4317, and it is the analysis nearly every buyer asking for AISI 4317 forgings actually wants.
We supply AISI 4317 forgings to the EN 10084 18CrNiMo7-6 (1.6587) analysis by default, because that is what the market means by the name. If your specification calls for the SAE 43xx analysis instead, put the required element ranges on the purchase order and we will work to them. Either way, the ordered chemistry is what appears on the mill certificate.
| Reading of the name | C | Cr | Ni | Mo | Where it is used |
|---|---|---|---|---|---|
| EN 10084 18CrNiMo7-6 / 1.6587 | 0.15–0.21 | 1.50–1.80 | 1.40–1.70 | 0.25–0.35 | The commercial default. Used on most supplier datasheets and on this page. |
| SAE 43xx family, former SAE 4317 | 0.15–0.20 | 0.40–0.60 | 1.65–2.00 | 0.20–0.30 | Legacy American drawings. Inactive SAE grade, so verify against the drawing. |
| SAE 43xx figures are the nominal family ranges, shown for comparison. Confirm the exact limits against the governing issue of the specification before ordering. | |||||
What is the chemical composition of AISI 4317?
Supplied by Jiangyin Jiangnan Metal Co., Ltd. to the EN 10084 18CrNiMo7-6 (1.6587) analysis, AISI 4317 contains 0.15 to 0.21 % carbon, up to 0.40 % silicon, 0.50 to 0.90 % manganese, 1.40 to 1.70 % nickel, 1.50 to 1.80 % chromium and 0.25 to 0.35 % molybdenum. Phosphorus is held to 0.025 % maximum and sulphur to 0.035 % maximum. The balance is iron.
| Element | Symbol | Min % | Max % | What it does |
|---|---|---|---|---|
| Carbon | C | 0.15 | 0.21 | Held low so the core stays tough. Surface carbon is added later by carburizing |
| Silicon | Si | – | 0.40 | Deoxidiser carried over from steelmaking |
| Manganese | Mn | 0.50 | 0.90 | Hardenability, and ties up sulphur |
| Nickel | Ni | 1.40 | 1.70 | Core toughness, particularly at low temperature |
| Chromium | Cr | 1.50 | 1.80 | Hardenability, case wear resistance, carbide stability |
| Molybdenum | Mo | 0.25 | 0.35 | Hardenability, and holds off temper embrittlement |
| Phosphorus | P | – | 0.025 | Residual, limited to protect toughness |
| Sulphur | S | – | 0.035 | Residual. Controlled additions available for machinability |
| Iron | Fe | Balance | – | |
| Cast or heat analysis. Product analysis tolerances apply per EN 10084. Tighter limits, controlled sulphur for machinability, or restricted residuals can be agreed at order entry. | ||||
We melt AISI 4317 by the EAF, LF and VD route: electric arc furnace melting, ladle furnace refining, then vacuum degassing. Degassing matters on this grade. Gear teeth and bearing races fail from sub surface inclusions long before they wear out on the surface.
What is AISI 4317 equivalent to?
AISI 4317 is most often cross referenced to EN 18CrNiMo7-6 and DIN 1.6587 in Germany, to 17CrNiMo6 under the older DIN 17210, to BS 970 820M17 and 822M17 in the United Kingdom, and to AFNOR 18NCD6 in France. The nearest Japanese grades are JIS SNCM420 and SNCM815. The nearest Chinese grades are GB 18CrNiMo7-6 and 20CrNi2Mo.
| Country and standard | Grade | Match |
|---|---|---|
| Germany, EN 10084 | 18CrNiMo7-6, material no. 1.6587 | Direct |
| Germany, DIN 17210 (withdrawn) | 17CrNiMo6 | Direct, former designation |
| International, ISO 683-3 | 18CrNiMo7-6 | Direct |
| United Kingdom, BS 970 Part 3 | 820M17, 822M17, former EN354 and EN355 | Near |
| France, AFNOR | 18NCD6 | Near |
| Spain, UNE | 14NiCrMo13 | Near |
| Japan, JIS G4053 | SNCM420, SNCM815 | Near |
| China, GB/T 3077 | 18CrNiMo7-6, 20CrNi2Mo | Near |
| Australia, AS 1444 | X4317, X4317H | Near, proprietary designation |
| United States, SAE (inactive) | SAE 4317 | See the designation note |
| Equivalents are nearest match guides for enquiry purposes, not drop in substitutions. Hardenability bands, residual limits and test requirements differ between standards, so state the governing specification on the purchase order. | ||
Mechanical properties of AISI 4317
Annealed, AISI 4317 is supplied at 229 HBW maximum. After carburizing, hardening and low temperature tempering it reaches a case hardness of about 58 to 62 HRC, with an indicative core tensile strength of 1050 to 1350 MPa, or 152 to 196 ksi.
| Condition | Tensile Rm | Yield Rp0.2 | Elongation A5 | Impact KV | Hardness |
|---|---|---|---|---|---|
| Annealed, as delivered | – | – | – | – | 229 HBW max, about 22 HRC |
| Normalized | – | – | – | – | About 210 to 255 HBW |
| Core, carburized then hardened and tempered at 180 to 200 °C | 1050–1350 MPa | 785 MPa min | 9 % min | 30 J min | About 32 to 42 HRC |
| Carburized case surface | – | – | – | – | 58 to 62 HRC, about 650 to 750 HV |
| Indicative values for design and enquiry. What a part actually achieves depends on section size, forging ratio, the carburizing cycle and the test position. Guaranteed values are the ones stated on the order and reported on the EN 10204 certificate. | |||||
| Property | Metric | Imperial |
|---|---|---|
| Density | 7.85 g/cm³ | 0.284 lb/in³ |
| Modulus of elasticity | About 210 GPa | About 30.5 × 10⁶ psi |
| Thermal conductivity | About 40 W/m·K | About 23 BTU/hr·ft·°F |
| Thermal expansion, 20 to 300 °C | About 12.5 × 10⁻⁶/K | About 6.9 × 10⁻⁶/°F |
| Magnetic | Yes, ferromagnetic in all conditions | |
| Corrosion resistance | None. AISI 4317 is not a stainless steel and needs oiling, plating or painting for storage and service | |
Heat treatment of AISI 4317
AISI 4317 is a carburizing steel, so its strength comes from a two part structure: a high carbon martensitic case over a low carbon tough core. The cycles below are the conventional ones for the grade. A works procedure still has to be written around the actual part.
| Operation | Temperature | Cooling | Purpose |
|---|---|---|---|
| Forging | 1100 to 1180 °C (2010 to 2155 °F) | Still air, slow cool on heavy sections | Shape and grain flow |
| Normalizing | 850 to 890 °C (1560 to 1635 °F) | Still air | Refine and even out the forged structure |
| Soft annealing | 650 to 700 °C (1200 to 1290 °F) | Furnace cool | Bring hardness down to 229 HBW max for machining |
| Carburizing | 880 to 980 °C (1615 to 1795 °F) | Per cycle | Raise surface carbon to roughly 0.7 to 0.9 % |
| Core hardening | 830 to 870 °C (1525 to 1600 °F) | Oil quench | Harden case and core |
| Tempering | 150 to 200 °C (300 to 390 °F) | Air | Take out quenching stress without losing case hardness |
| Stress relief | 550 to 650 °C (1020 to 1200 °F) | Furnace or air | After rough machining, before carburizing |
| Direct quenching, single quenching and double quenching are all used on this grade. The route follows from section size, the distortion tolerance and the case depth called for. | |||
Case hardening depth
Case hardening depth is normally specified at the 550 HV limit in the finished part. A deeper case carries more contact load, but it is more brittle at the tooth tip and takes longer to produce. Gear designers usually tie case depth to the module of the gear rather than asking for the deepest case the furnace can give.
AISI 4317 forged product forms
Jiangyin Jiangnan Metal Co., Ltd. produces AISI 4317 as open die forgings and seamless rolled rings, made to customer drawing. The regular forms are rings, gear and pinion blanks, shafts, discs, sleeves and bushings, flanges, blocks and round bars.
| Forged form | Usual delivery condition | Notes |
|---|---|---|
| Seamless rolled rings and forged rings | Normalized and annealed, rough machined | Rolled from a pierced blank for continuous circumferential grain |
| Gear blanks and pinion blanks | Annealed, 229 HBW max, machining allowance | Cut and carburized by the customer |
| Shafts and stepped shafts | Normalized and annealed | Upset and drawn down on the press to drawing |
| Discs, blanks and blocks | Annealed, rough machined | Forged with an upset ratio suited to the section |
| Sleeves, bushings and hollow forgings | Annealed, bored | Pierced and expanded rather than drilled from solid |
| Flanges | Normalized and annealed | Not for pressure duty in this grade, see the note below |
| Round bars | Annealed, black or peeled | Forged bar rather than rolled bar |
| Everything is forged to drawing. Send a drawing, a sketch or the rough dimensions and we will confirm feasibility, weight and price, and tell you straight away if the part is outside what our press and ring mill can take. | ||
Forged AISI 4317 beats bar stock on gear and bearing parts because open die forging and ring rolling put the grain flow where the load is. A ring rolled from a pierced blank keeps continuous circumferential grain, which lifts fatigue strength at the tooth root compared with a ring cut out of plate.
Where AISI 4317 forgings are used
AISI 4317 gets specified when a part has to take heavy contact load on its surface and heavy bending load in its body, at a section too large for a leaner carburizing steel to harden through.
Power transmission and gearing
Heavy duty gears, pinions, ring gears, gear shafts, planet carriers and spline shafts for industrial gearboxes, turbine drives, gas compressors and marine propulsion. This is the main use of the grade and the reason it carries so much nickel and chromium.
Wind energy
Main shafts, planetary gear components and bearing rings in wind turbine gearboxes. Deep hardenability, low temperature core toughness and clean steel from vacuum degassing are standing requirements in this sector.
Mining, cement and heavy machinery
Pinions and girth gear segments for cement mills, sugar mills and concrete mixers. Crusher shafts, eccentric shafts, rolls, sprockets and heavy duty bushings.
Bearings and wear components
Large bearing rings and races, cam followers, tappets, wear pins, clutch dogs, wire guides and extractor components, all case hardened for surface life.
Oil, gas and process equipment
Forged shafts, sleeves, bushings and rings for chemical and plunger pumps, industrial air compressors, power generators and subsea production equipment.
How AISI 4317 forgings are produced
This is the route we follow on an AISI 4317 forging, from heat to dispatch.
- Melting, EAF then LF then VD The heat is melted in an electric arc furnace, refined in a ladle furnace and vacuum degassed, which holds down hydrogen, oxygen and non metallic inclusions.
- Heating and open die forging The ingot or bloom is soaked at 1100 to 1180 °C and forged on an open die press with a controlled forging ratio, so the grain flow follows the shape of the finished part.
- Ring rolling On ring geometries the blank is upset, pierced and rolled on a seamless ring rolling mill to the finished section.
- Heat treatment The forging is normalized and annealed, or normalized and tempered, down to a machinable delivery hardness of 229 HBW maximum, ready for carburizing.
- Rough machining The piece is rough or semi finish machined to the drawing allowance, so testing happens on the representative section and any sub surface defect is opened up before shipment rather than after.
- Testing Chemical analysis, mechanical and hardness testing, grain size, Jominy hardenability, magnetic particle inspection and ultrasonic testing, as called for on the order.
- Marking, certification and dispatch The forging is stamped with the heat number and released with an EN 10204 3.1 certificate, or an EN 10204 3.2 certificate with third party inspection.
Testing and certification for AISI 4317 forgings
AISI 4317 forgings from Jiangyin Jiangnan Metal Co., Ltd. are ultrasonically tested to EN 10228-3, SEP 1921 or ASTM A388, and certified to EN 10204 3.1 or EN 10204 3.2. The acceptance class comes from the drawing or the customer specification.
| Test or document | Standard | Notes |
|---|---|---|
| Chemical analysis | EN 10084, ASTM A29/A29M | Cast analysis, product analysis on request |
| Tensile and impact testing | ISO 6892-1, ASTM A370 | Test position and orientation per the order |
| Hardness | ISO 6506 (HBW), ISO 6508 (HRC) | Delivery hardness 229 HBW max |
| Grain size | ASTM E112, ISO 643 | Fine grain practice, usually 5 or finer |
| Jominy end quench hardenability | ISO 642, ASTM A255 | Available as an H band requirement |
| Ultrasonic testing | EN 10228-3, SEP 1921, ASTM A388/A388M | Class per the drawing |
| Magnetic particle inspection | EN 10228-1, ASTM E1444 | Surface and near surface indications |
| Inspection certificate | EN 10204 3.1 | Issued by our works inspection department |
| Inspection certificate, third party | EN 10204 3.2 | Witnessed by an agreed inspection body |
| Tell us the test plan with the enquiry. Ultrasonic class and test position affect the machining allowance we forge on, so it is cheaper to know before the ingot is cut than after. | ||
AISI 4317 against other forging grades
Choose AISI 4317 over AISI 8620 when the section is too large for 8620 to harden through, and over AISI 4140 when the part needs a hard wear surface rather than uniform through hardness. AISI 8620 is cheaper on small case hardened parts. AISI 4140 remains the standard pick for through hardened shafts and flanges.
| AISI 4317 | AISI 8620 | AISI 4320 | AISI 4140 | |
|---|---|---|---|---|
| Steel type | Case hardening | Case hardening | Case hardening | Through hardening |
| Carbon % | 0.15–0.21 | 0.18–0.23 | 0.17–0.22 | 0.38–0.43 |
| Chromium % | 1.50–1.80 | 0.40–0.60 | 0.40–0.60 | 0.80–1.10 |
| Nickel % | 1.40–1.70 | 0.40–0.70 | 1.65–2.00 | – |
| Molybdenum % | 0.25–0.35 | 0.15–0.25 | 0.20–0.30 | 0.15–0.25 |
| Hardenability | Very deep | Shallow to medium | Deep | Medium to deep |
| Surface hardness | 58 to 62 HRC, carburized | 58 to 62 HRC, carburized | 58 to 62 HRC, carburized | 28 to 34 HRC, quenched and tempered |
| Relative cost | High | Low | Medium to high | Low to medium |
| Best for | Large gears, pinions and bearing rings in heavy sections | Small and medium case hardened parts | Medium gears and shafts | Through hardened shafts, flanges, blocks |
| Grade page | This page | AISI 8620 forgings | AISI 4320 forgings | AISI 4140 forgings |
| Composition ranges for AISI 8620, 4320 and 4140 are the nominal SAE ranges, shown for comparison. AISI 4317 figures are the EN 10084 18CrNiMo7-6 limits we supply to. | ||||
Questions and answers about AISI 4317
What is AISI 4317 steel?
AISI 4317 is a low carbon nickel chromium molybdenum case hardening (carburizing) steel. It is carburized to give a hard, wear resistant surface of about 58 to 62 HRC over a tough, high strength core, which is why it is used for heavily loaded gears, pinions, shafts and bearing components. In commercial trade the AISI 4317 designation is most often supplied to the EN 10084 analysis of 18CrNiMo7-6 (material number 1.6587), also known by the older designation 17CrNiMo6.
What is the chemical composition of AISI 4317?
As supplied by Jiangyin Jiangnan Metal Co., Ltd. against the EN 10084 18CrNiMo7-6 (1.6587) analysis, AISI 4317 contains 0.15 to 0.21 percent carbon, up to 0.40 percent silicon, 0.50 to 0.90 percent manganese, 1.40 to 1.70 percent nickel, 1.50 to 1.80 percent chromium, 0.25 to 0.35 percent molybdenum, a maximum of 0.025 percent phosphorus and a maximum of 0.035 percent sulphur, with the balance iron.
What is AISI 4317 equivalent to?
AISI 4317 is commonly cross referenced to EN 18CrNiMo7-6 and DIN 1.6587 in Germany, the older DIN 17210 designation 17CrNiMo6, BS 970 820M17 and 822M17 in the United Kingdom, AFNOR 18NCD6 in France, JIS SNCM420 and SNCM815 in Japan as nearest grades, GB 18CrNiMo7-6 and 20CrNi2Mo in China as nearest grades, and AS 1444 X4317 in Australia. Cross references are nearest match guides rather than drop in substitutions, so the ordered analysis should always be stated on the purchase order.
What hardness can AISI 4317 reach after carburizing?
After carburizing, hardening and low temperature tempering, AISI 4317 typically reaches a case hardness of 58 to 62 HRC with a core tensile strength of roughly 1050 to 1350 MPa. In the annealed delivery condition it is normally supplied at a maximum of 229 HBW, about 22 HRC, so that it can be machined before case hardening.
What forged product forms are available in AISI 4317?
Jiangyin Jiangnan Metal Co., Ltd. produces AISI 4317 as open die forged and seamless rolled rings, gear blanks and pinion blanks, shafts and stepped shafts, round bars, discs and blanks, sleeves and bushings, flanges, blocks and hollow forgings, all made to customer drawing rather than to a fixed stock list.
Which tests and certificates are supplied with AISI 4317 forgings?
AISI 4317 forgings from Jiangyin Jiangnan Metal Co., Ltd. can be supplied with chemical analysis, mechanical testing, hardness testing, grain size and Jominy end quench hardenability results, magnetic particle inspection and ultrasonic testing to EN 10228-3, SEP 1921 or ASTM A388. Certification is issued to EN 10204 3.1, or to EN 10204 3.2 with third party inspection when required.
What is the difference between AISI 4317 and AISI 8620?
Both AISI 4317 and AISI 8620 are carburizing steels, but AISI 4317 carries far more nickel and chromium, which gives it much deeper hardenability and better core toughness in heavy sections. AISI 8620 is the more economical choice for small and medium case hardened parts, while AISI 4317 is selected for large section gears, pinions and shafts where the core must harden through and stay tough.
How do I request a quotation for AISI 4317 forgings?
Send the drawing or the rough dimensions, the quantity, the required delivery condition and any test or certification requirements to sales@steelforgepieces.com, or call +86-189-2135-9659. Jiangyin Jiangnan Metal Co., Ltd. is located at No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China.
Request a quotation for AISI 4317 forgings
Send a drawing, a sketch or the rough dimensions. Include the quantity, the delivery condition you need, and any testing or certification required. We come back with feasibility, weight, price and lead time.
Jiangyin Jiangnan Metal Co., Ltd., open die forging factoryNo.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China
Telephone: +86-189-2135-9659
Email: sales@steelforgepieces.com
Website: www.steelforgepieces.com
Standards referenced
EN 10084, ISO 683-3, ASTM A29/A29M, EN 10204, EN 10228-3, ASTM A388/A388M, SEP 1921.