Steel 38CrMoAl-HR (Hot rolled)
Supply condition
GB 38CrMoAl · EN 1.8509, 41CrAlMo7 · JIS SACM645 · also Nitralloy 135
Cheapest mill supply condition for stock that will be fully heat treated by the user.
Values for the HR condition
Other 38CrMoAl tempers and conditions
38CrMoAl is listed in 8 conditions; see the grade overview at 38CrMoAl.
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 | — |
HRThis page 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-HR?
38CrMoAl-HR is 38CrMoAl supplied in the HR condition — cheapest mill supply condition for stock that will be fully heat treated by the user. 38CrMoAl-HR has a yield strength of 600 MPa (87 ksi) and a tensile strength of 900 MPa (131 ksi) — stronger than 77% of steel grades. Elongation at break is 14% and the elastic modulus is 210 GPa (30.5 Msi). 38CrMoAl-HR 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). Q&T is the default condition FabDigit quotes; HR is available on request or by drawing note.
Advantages
- Polishes to a fine finish — 70/100, better than 87% of steel grades
- High strength — 600 MPa (87 ksi), better than 77% of steel grades
Limitations
- Difficult to machine — 35/100, worse than 84% of steel grades
- Difficult to weld — 20/100, worse than 84% of steel grades
- Low fracture toughness — 55 MPa·√m (50.1 ksi·√in), worse than 82% of steel grades
- Limited ductility — 14%, worse than 75% of steel grades
38CrMoAl-HR properties
Typical room-temperature values for 38CrMoAl-HR; 22 are specific to this condition. Other listed values are 38CrMoAl reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
38CrMoAl-HR 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-HR has a yield strength of 600 MPa (87 ksi) and a tensile strength of 900 MPa (131 ksi) — stronger than 77% of steel grades. Elongation at break is 14% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
38CrMoAl-HR is rated for continuous service to 400°C (752 °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-HR 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-HR 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-HR's machinability is fair (35/100, worse than 84% of steel grades); weldability poor (20/100); formability poor (25/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 38CrMoAl-HR
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.
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.
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 | — |
38CrMoAl-HR — frequently asked
What is 38CrMoAl-HR used for?
38CrMoAl-HR 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-HR?
38CrMoAl-HR has a typical yield strength of 600 MPa (87 ksi) and a tensile strength of 900 MPa (131 ksi) — stronger than 77% of steel grades. Strength varies by condition: see the 8 listed tempers.
Is 38CrMoAl-HR easy to machine?
Not especially — machinability is rated fair (35/100, worse than 84% 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-HR be welded?
Not readily — weldability is rated poor (20/100). 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-HR?
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-HR 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-HR?
38CrMoAl-HR is rated for continuous use to about 400°C (752 °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.
Can FabDigit make parts in 38CrMoAl-HR?
Yes — 38CrMoAl-HR 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. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.