Steel 38CrMoAlA
GB 38CrMoAlA · EN 38CrMoAl A, 41CrAlMo7-10
China's most widely used dedicated nitriding steel, containing Al to promote a hard, wear-resistant nitrided case after gas nitriding; used for precision shafts, gears, and spindles requiring high surface hardness with a tough core.
Values for the Q&T condition
38CrMoAlA tempers and conditions
38CrMoAlA 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 |
|---|---|---|---|---|---|---|
Annealed (softened, ≤229 HB) | Pick for rough machining of large blanks or for stock that will be fully heat treated afterwards. | 450 | 720 | 20 | 210 HB | — |
Hot rolled | Cheapest mill condition for forging or re-heat-treatment; hardness and structure not controlled for machining. | 550 | 850 | 16 | 25 HRC | 8.2 % IACS |
Normalized (~930–950 °C, air cooled) | Use to homogenise forgings and refine grain before quenching; not a final service condition. | 620 | 900 | 15 | 27 HRC | 8 % IACS |
Cold drawn | Pick for small-diameter precision shafting where dimensional accuracy matters more than core strength. | 700 | 850 | 10 | 25 HRC | 8 % IACS |
Q&T to 28–32 HRC | Specify when impact toughness and machinability of the finished part outweigh core strength. | 830 | 980 | 17 | 30 HRC | — |
Q&TDefault Quenched and tempered | Standard supply and pre-nitriding condition: tough ~1000 MPa core that stays dimensionally stable during nitriding. | 880 | 1,030 | 16 | 32 HRC | — |
Q&T + gas/ion nitrided | The service condition for this grade: extreme surface hardness and wear/scuffing resistance on a tough Q&T core. | 880 | 1,030 | 14 | 68 HRC | — |
Q&T to 32–36 HRC | Choose for heavily loaded screws, spindles and gears where core strength governs before nitriding. | 950 | 1,100 | 14 | 34 HRC | — |
What is 38CrMoAlA?
China's most widely used dedicated nitriding steel, containing Al to promote a hard, wear-resistant nitrided case after gas nitriding; used for precision shafts, gears, and spindles requiring high surface hardness with a tough core. 38CrMoAlA has a density of 7.8 g/cm³ (0.282 lb/in³), lighter than 87% of steel grades. It melts at 1,420°C (2,588 °F). 38CrMoAlA 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 38CrMoAlA used for?
- Nitrided precision shafts
- Extruder and injection screws
- Gears and pinions
- Machine tool spindles
- Valve stems and spindles
- Hydraulic piston rods
- Wear sleeves and bushings
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 — 20/100, worse than 84% of steel grades
- Poor heat conductor — 33 W/m·K (19.1 BTU/hr·ft·°F), worse than 80% of steel grades
- Limited formability — 20/100, worse than 80% of steel grades
38CrMoAlA properties
Typical room-temperature values for 38CrMoAlA-Q&T; bars are the position among steel grades.
Physical3
38CrMoAlA has a density of 7.8 g/cm³ (0.282 lb/in³), lighter than 87% of steel grades. It melts at 1,420°C (2,588 °F).
Mechanical16
38CrMoAlA 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
38CrMoAlA is rated for continuous service to 500°C (932 °F). It conducts heat at 33 W/m·K (19.1 BTU/hr·ft·°F), worse than 80% of steel grades. Thermal expansion is 11.9 µm/m·K (6.61 µin/in·°F).
Electrical3
38CrMoAlA conducts electricity at 7.8 % IACS, worse than 57% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (12/100), worse than 53% of steel grades.
Sustainability4
Producing a kilogram of 38CrMoAlA takes about 34 MJ of energy and emits 2.3 kg of CO₂ — more than 82% of steel grades. Typical recycled content is 30%.
Manufacturability8
38CrMoAlA's machinability is fair (45/100, worse than 65% of steel grades); weldability poor (20/100); 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. 38CrMoAlA is highlighted; hover a dot for its name, or open the interactive family chart.
Working with 38CrMoAlA
Is 38CrMoAlA easy to machine?
Machine in the Q&T condition with rigid setups, coated carbide and generous coolant; finish-grind after nitriding since the case is essentially unmachinable.
Can 38CrMoAlA be welded?
Poor weldability — high Al/Cr/Mo and 0.38 % C give hardening and cracking; if unavoidable use 250–350 °C preheat, low-hydrogen filler and immediate stress relief below the temper temperature, and never weld a nitrided surface.
Can 38CrMoAlA be formed, bent or molded?
Hot forge at 1150–850 °C followed by slow cooling and annealing; cold forming is impractical except mild straightening of soft bar.
Manufacturability
The process limits FabDigit applies to 38CrMoAlA. Every 38CrMoAlA part is priced by an engineer; design inside these and the quote comes back without a redesign loop.
CNC machining
| Machinability | Better45 / 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 | Better20 / 100 |
38CrMoAlA 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 |
| Alnitride former — key to the AlN-rich hard case | 0.7 – 1.1 | 0.9 |
| Niresidual | ≤ 0.3 | |
| Curesidual | ≤ 0.2 | |
| PA grade = high quality, restricted P | ≤ 0.03 | |
| SA grade = high quality, restricted S | ≤ 0.03 | |
| Fe | balance |
What surface finishes work on 38CrMoAlA?
Stress relieve at 550–600 °C before nitriding, then gas or plasma nitride at 500–540 °C for 0.3–0.6 mm case; finish by lapping/polishing or light grinding, and oil, phosphate or blacken any non-nitrided surface for rust protection.
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 38CrMoAlA in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- EN / DIN / Werkstoff-Nr.
- 38CrMoAl A41CrAlMo7-101.8509
- GB (China)
- 38KhMYuA
- Also called
- 38CrMoAl
- Other
- 38Kh2MYuASACM645
How much does 38CrMoAlA cost?
38CrMoAlA 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.
38CrMoAlA — frequently asked
What is 38CrMoAlA used for?
38CrMoAlA is typically used for nitrided precision shafts, extruder and injection screws, gears and pinions, machine tool spindles, valve stems and spindles and hydraulic piston rods. In short: nitridable Cr-Mo-Al bar.
What is the yield strength of 38CrMoAlA?
38CrMoAlA 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 38CrMoAlA easy to machine?
Reasonably — machinability is rated fair (45/100, worse than 65% of steel grades). Machine in the Q&T condition with rigid setups, coated carbide and generous coolant; finish-grind after nitriding since the case is essentially unmachinable.
Can 38CrMoAlA be welded?
Not readily — weldability is rated poor (20/100). Poor weldability — high Al/Cr/Mo and 0.38 % C give hardening and cracking; if unavoidable use 250–350 °C preheat, low-hydrogen filler and immediate stress relief below the temper temperature, and never weld a nitrided surface.
What surface finishes work on 38CrMoAlA?
Stress relieve at 550–600 °C before nitriding, then gas or plasma nitride at 500–540 °C for 0.3–0.6 mm case; finish by lapping/polishing or light grinding, and oil, phosphate or blacken any non-nitrided surface for rust protection.
Can 38CrMoAlA be formed, bent or molded?
Hot forge at 1150–850 °C followed by slow cooling and annealing; cold forming is impractical except mild straightening of soft bar.
What is the maximum service temperature of 38CrMoAlA?
38CrMoAlA 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 38CrMoAlA Q&T and 38CrMoAlA-HR?
Q&T is the default condition — standard supply and pre-nitriding condition: tough ~1000 MPa core that stays dimensionally stable during nitriding. HR: cheapest mill condition for forging or re-heat-treatment; hardness and structure not controlled for machining. Yield strength is 880 MPa in Q&T versus 550 MPa in HR.
How much does 38CrMoAlA cost?
38CrMoAlA 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 38CrMoAlA?
Yes — 38CrMoAlA 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
- ASM Handbook Vol.1: Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
- ASM Handbook Vol.4A: Steel Heat Treating Fundamentals and Processes (nitriding steels) — ASM International (2013)
- 38CrMoAl / 34CrAlMo5 nitriding steel bar datasheet — / Böhler (2022)
- (38CrMoAlA) — 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.