Steel 38CrMoAl
GB 38CrMoAl · EN 1.8509, 41CrAlMo7 · JIS SACM645 · also Nitralloy 135
38CrMoAl is an aluminium-bearing chromium-molybdenum nitriding steel (SACM645, 34CrAlMo5-10 / 1.8507, Nitralloy 135) in which about 1 % Al forms hard, stable nitrides during gas or ion nitriding.
Values for the Q&T condition
38CrMoAl tempers and conditions
38CrMoAl is supplied in 8 conditions, soft to hard. Q&T is the default FabDigit quotes; the values on this page are for it.
Compare all 8 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
full/soft annealed (approx. 840–870 °C, slow cool) | Softest condition for heavy machining, deep-hole drilling and cold straightening before final Q&T. | 450 | 720 | 22 | 215 HB | — |
Hot rolled | Cheapest mill supply condition for stock that will be fully heat treated by the user. | 600 | 900 | 14 | 27 HRC | 7.8 % IACS |
930–950 °C, air cool | Grain refinement and structure homogenising step for forgings prior to quench and temper. | 640 | 900 | 16 | 26 HRC | 7.8 % IACS |
Cold drawn | Close-tolerance bright bar for small nitrided pins, gauges and bushings with minimal machining allowance. | 700 | 850 | 10 | 25 HRC | 7.8 % IACS |
Quench and temper to a specified core hardness band | Order this when a machinable but strong core hardness must be guaranteed before nitriding. | 830 | 980 | 17 | 30 HRC | 7.8 % IACS |
Q&TDefault Quenched and tempered | Standard delivery/core condition: tough tempered-sorbite core that will not soften during subsequent nitriding. | 880 | 1,030 | 16 | 32 HRC | — |
Q&T + gas nitrided | The intended service condition: >900 HV AlN-hardened case for wear, galling and fatigue resistance on a tough core. | 880 | 1,030 | 14 | 68 HRC | — |
Higher core-strength quench and temper | Chosen for extruder screws/barrels and shafts needing maximum core support under the nitrided case. | 950 | 1,100 | 14 | 34 HRC | 7.8 % IACS |
What is 38CrMoAl?
38CrMoAl is an aluminium-bearing chromium-molybdenum nitriding steel (SACM645, 34CrAlMo5-10 / 1.8507, Nitralloy 135) in which about 1 % Al forms hard, stable nitrides during gas or ion nitriding. Engineers order it as quenched-and-tempered bar and forgings — typically 880 MPa yield, 1030 MPa tensile, 16 % elongation and 310 HB (32 HRC), with service to 500 °C — where a 0.3–0.6 mm case above 900 HV is needed over a tough core. It is effectively non-weldable, cuts slowly (machinability 40), and the base steel rusts readily, so plating, phosphating or oiling is required; 42CrMo4 is the alternative when welding or lower cost governs. 38CrMoAl has a density of 7.8 g/cm³ (0.282 lb/in³), lighter than 87% of steel grades. It melts at 1,450°C (2,642 °F). 38CrMoAl has a yield strength of 880 MPa (128 ksi) and a tensile strength of 1,030 MPa (149 ksi) — stronger than 89% of steel grades. Elongation at break is 16% and the elastic modulus is 210 GPa (30.5 Msi).
What is 38CrMoAl used for?
- Nitrided drive and spindle shafts
- Gear and pinion surfaces
- Extruder screws and barrels
- Hydraulic piston rods
- Valve stems and spindles
- Precision gauges and measuring tools
- Cam and guide plates
Advantages
- High service temperature — 500°C (932 °F), better than 90% of steel grades
- High strength — 880 MPa (128 ksi), better than 89% of steel grades
- Polishes to a fine finish — 70/100, better than 87% of steel grades
Limitations
- Difficult to weld — 18/100, worse than 87% of steel grades
- Limited formability — 20/100, worse than 80% of steel grades
- Difficult to machine — 40/100, worse than 77% of steel grades
38CrMoAl properties
Typical room-temperature values for 38CrMoAl-Q&T; bars are the position among steel grades.
Physical3
38CrMoAl has a density of 7.8 g/cm³ (0.282 lb/in³), lighter than 87% of steel grades. It melts at 1,450°C (2,642 °F).
Mechanical16
38CrMoAl has a yield strength of 880 MPa (128 ksi) and a tensile strength of 1,030 MPa (149 ksi) — stronger than 89% of steel grades. Elongation at break is 16% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
38CrMoAl is rated for continuous service to 500°C (932 °F). It conducts heat at 36 W/m·K (20.8 BTU/hr·ft·°F), worse than 73% of steel grades. Thermal expansion is 11.8 µm/m·K (6.56 µin/in·°F).
Electrical3
38CrMoAl conducts electricity at 7.8 % IACS, worse than 57% of steel grades.
Chemical & Environmental3
Corrosion resistance is poor (16/100), better than 79% of steel grades.
Sustainability4
Producing a kilogram of 38CrMoAl takes about 34 MJ of energy and emits 2.4 kg of CO₂ — more than 82% of steel grades. Typical recycled content is 25%.
Manufacturability7
38CrMoAl's machinability is fair (40/100, worse than 77% of steel grades); weldability poor (18/100); formability poor (20/100).
Common Calculations5
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the steel family
Yield strength against density for every steel grade FabDigit runs. 38CrMoAl is highlighted; hover a dot for its name, or open the interactive family chart.
Working with 38CrMoAl
Is 38CrMoAl easy to machine?
Machine in the annealed or Q&T (28–32 HRC) state with rigid setups and coated carbide; leave 0.05–0.15 mm grinding stock because nitriding grows and slightly distorts parts, and never machine the nitrided case except by grinding/lapping.
Can 38CrMoAl be welded?
Effectively non-weldable for service parts — high hardenability plus ~1 % Al causes cracking and hard HAZ; if unavoidable, preheat 300–400 °C, use low-hydrogen matched consumables and re-temper immediately.
Can 38CrMoAl be formed, bent or molded?
Hot forge 1100–850 °C with slow cooling and mandatory normalise/anneal; cold forming is limited to light straightening in the annealed condition.
Manufacturability
The process limits FabDigit applies to 38CrMoAl. Every 38CrMoAl part is priced by an engineer; design inside these and the quote comes back without a redesign loop.
CNC machining
| Machinability | Better40 / 100 |
|---|---|
| ISO material group | P.2 |
| Cutting speed (rough / finish) | 180 / 210 m/min |
| Minimum wall | 0.8 mm |
| Minimum internal radius | 1 mm |
| Drill depth limit | 5× diameter |
| Best surface (machined / polished) | Ra 1.6 / — |
| Hardenable after machining | No |
Sheet metal
| Formability | Fair20 / 100 |
|---|---|
| Weldability | Better18 / 100 |
38CrMoAl chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| C | 0.35 – 0.42 | 0.38 |
| Si | 0.2 – 0.45 | 0.3 |
| Mn | 0.3 – 0.6 | 0.45 |
| Cr | 1.35 – 1.65 | 1.5 |
| Mo | 0.15 – 0.25 | 0.2 |
| Alforms hard AlN in the nitrided case | 0.7 – 1.1 | 0.9 |
| Niresidual | ≤ 0.3 | |
| Curesidual | ≤ 0.3 | |
| P | ≤ 0.03 | |
| S | ≤ 0.03 | |
| Fe | balance |
What surface finishes work on 38CrMoAl?
Gas or ion nitride at 500–540 °C after stress relief for a 0.3–0.6 mm case >900 HV; lap or grind off the brittle white layer, then oil, phosphate, black-oxide or chrome plate since the base steel rusts readily.
Surface treatments FabDigit runs on steel parts — pick them in the quote configurator or call them out on the drawing. Each links to its datasheet in the surface-finish library (thickness, specs, call-out, material verdicts).
Plating
CVD Coating
Black / Phosphate
Thermal Spray
Equivalent designations
Standards and trade names that resolve to Steel 38CrMoAl in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- EN / DIN / Werkstoff-Nr.
- 1.850941CrAlMo7
- JIS
- SACM645
- Trade names
- Nitralloy 135
- Similar grades
- 34CrAlMo5-101.8507
How much does 38CrMoAl cost?
38CrMoAl is a standard-cost steel ($$), cheaper than about 71% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
38CrMoAl — frequently asked
What is 38CrMoAl used for?
38CrMoAl is typically used for nitrided drive and spindle shafts, gear and pinion surfaces, extruder screws and barrels, hydraulic piston rods, valve stems and spindles and precision gauges and measuring tools. In short: nitridable Cr-Mo-Al bar.
What is the yield strength of 38CrMoAl?
38CrMoAl has a typical yield strength of 880 MPa (128 ksi) and a tensile strength of 1,030 MPa (149 ksi) — stronger than 89% of steel grades. Strength varies by condition: see the 8 listed tempers.
Is 38CrMoAl easy to machine?
Not especially — machinability is rated fair (40/100, worse than 77% of steel grades). Machine in the annealed or Q&T (28–32 HRC) state with rigid setups and coated carbide; leave 0.05–0.15 mm grinding stock because nitriding grows and slightly distorts parts, and never machine the nitrided case except by grinding/lapping.
Can 38CrMoAl be welded?
Not readily — weldability is rated poor (18/100). Effectively non-weldable for service parts — high hardenability plus ~1 % Al causes cracking and hard HAZ; if unavoidable, preheat 300–400 °C, use low-hydrogen matched consumables and re-temper immediately.
What surface finishes work on 38CrMoAl?
Gas or ion nitride at 500–540 °C after stress relief for a 0.3–0.6 mm case >900 HV; lap or grind off the brittle white layer, then oil, phosphate, black-oxide or chrome plate since the base steel rusts readily.
Can 38CrMoAl be formed, bent or molded?
Hot forge 1100–850 °C with slow cooling and mandatory normalise/anneal; cold forming is limited to light straightening in the annealed condition.
What is the maximum service temperature of 38CrMoAl?
38CrMoAl is rated for continuous use to about 500°C (932 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between 38CrMoAl Q&T and 38CrMoAl-HR?
Q&T is the default condition — standard delivery/core condition: tough tempered-sorbite core that will not soften during subsequent nitriding. HR: cheapest mill supply condition for stock that will be fully heat treated by the user. Yield strength is 880 MPa in Q&T versus 600 MPa in HR.
How much does 38CrMoAl cost?
38CrMoAl is a standard-cost steel ($$), cheaper than about 71% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Can FabDigit make parts in 38CrMoAl?
Yes — 38CrMoAl is available for CNC machining and sheet metal; every part is priced by an engineer rather than instantly. Upload a STEP file to get a price and a DFM check.
Sources
- GB/T 3077 Alloy structural steels — SAC (China) (2015)
- EN 10085 Nitriding steels — 41CrAlMo7-10 (1.8509) — CEN (2001)
- ASM Handbook Vol. 1: Properties and Selection — Irons, Steels — ASM International (1990)
- ASM Handbook Vol. 4A: Steel Heat Treating — Nitriding — ASM International (2013)
- Nitriding steel 1.8509 / N135M datasheet — Böhler / voestalpine (2020)
- 38CrMoAl — Mysteel / 1688 (2026)
Property data is compiled from published supplier and standards handbooks and normalised for comparison; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.