Steel 38CrMoAlA · finish state
Steel 38CrMoAlA Q&T+Nitrided
Properties of the Q&T+Nitrided condition, compared with the other 38CrMoAlA tempers.
The service condition for this grade: extreme surface hardness and wear/scuffing resistance on a tough Q&T core.
What is 38CrMoAlA Q&T+Nitrided?
38CrMoAlA Q&T+Nitrided is 38CrMoAlA supplied in the Q&T+Nitrided condition — the service condition for this grade: extreme surface hardness and wear/scuffing resistance on a tough Q&T core. 38CrMoAlA Q&T+Nitrided has a yield strength of 880 MPa (128 ksi) and a tensile strength of 1,030 MPa (149 ksi) — stronger than 90% of steel grades. Elongation at break is 14% and the elastic modulus is 210 GPa (30.5 Msi). 38CrMoAlA Q&T+Nitrided 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). Q&T is the default condition FabDigit quotes; Q&T+Nitrided is available on request or by drawing note.
Advantages
- Polishes to a fine finish — 80/100, better than 97% of steel grades
- High service temperature — 520°C (968 °F), better than 92% of steel grades
- High strength — 880 MPa (128 ksi), better than 90% of steel grades
Limitations
- Difficult to machine — 5/100, worse than 100% of steel grades
- 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
- Limited ductility — 14%, worse than 75% of steel grades
38CrMoAlA Q&T+Nitrided properties
Typical room-temperature values for 38CrMoAlA Q&T+Nitrided — 12 properties are specific to this condition; the rest are grade-level values shared by every 38CrMoAlA temper. Each bar shows where the value sits among the steel grades in FabDigit's library — further right is higher.
Physical3
38CrMoAlA Q&T+Nitrided 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 Q&T+Nitrided has a yield strength of 880 MPa (128 ksi) and a tensile strength of 1,030 MPa (149 ksi) — stronger than 90% of steel grades. Elongation at break is 14% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
38CrMoAlA Q&T+Nitrided is rated for continuous service to 520°C (968 °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 Q&T+Nitrided conducts electricity at 7.8 % IACS, worse than 58% of steel grades.
Chemical & Environmental3
Corrosion resistance is poor (18/100), better than 83% of steel grades.
Sustainability4
Producing a kilogram of 38CrMoAlA Q&T+Nitrided 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 Q&T+Nitrided's machinability is not recommended (5/100, worse than 100% of steel grades); weldability poor (20/100); formability poor (20/100).
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Other 38CrMoAlA tempers and conditions
38CrMoAlA is also supplied in 7 other conditions. The full side-by-side table is on the 38CrMoAlA overview.
- Q&TDefaultStandard supply and pre-nitriding condition: tough ~1000 MPa core that stays dimensionally stable during nitriding.880 MPa yield · 32 HRC
- Q&T 32-36 HRCChoose for heavily loaded screws, spindles and gears where core strength governs before nitriding.950 MPa yield · 34 HRC
- Q&T+NitridedThe service condition for this grade: extreme surface hardness and wear/scuffing resistance on a tough Q&T core.880 MPa yield · 68 HRC
- Q&T 28-32 HRCSpecify when impact toughness and machinability of the finished part outweigh core strength.830 MPa yield · 30 HRC
- AnnealedPick for rough machining of large blanks or for stock that will be fully heat treated afterwards.450 MPa yield · 210 HB
Working with 38CrMoAlA Q&T+Nitrided
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.
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.
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 | — |
38CrMoAlA Q&T+Nitrided — frequently asked
What is 38CrMoAlA Q&T+Nitrided used for?
38CrMoAlA Q&T+Nitrided 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 Q&T+Nitrided?
38CrMoAlA Q&T+Nitrided has a typical yield strength of 880 MPa (128 ksi) and a tensile strength of 1,030 MPa (149 ksi) — stronger than 90% of steel grades. Strength varies by condition: see the 8 listed tempers.
Is 38CrMoAlA Q&T+Nitrided easy to machine?
Not especially — machinability is rated not recommended (5/100, worse than 100% 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 Q&T+Nitrided 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 Q&T+Nitrided?
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 Q&T+Nitrided 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 Q&T+Nitrided?
38CrMoAlA Q&T+Nitrided is rated for continuous use to about 520°C (968 °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.
Can FabDigit make parts in 38CrMoAlA Q&T+Nitrided?
Yes — 38CrMoAlA Q&T+Nitrided is available for CNC machining and sheet metal with instant online pricing. 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. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.