Steel 38CrMoAlA · heat-treated state · default condition
Steel 38CrMoAlA Q&T
Properties of the Q&T condition, compared with the other 38CrMoAlA tempers.
Standard supply and pre-nitriding condition: tough ~1000 MPa core that stays dimensionally stable during nitriding.
What is 38CrMoAlA Q&T?
38CrMoAlA Q&T is 38CrMoAlA heat treated to Q&T — standard supply and pre-nitriding condition: tough ~1000 MPa core that stays dimensionally stable during nitriding. 38CrMoAlA Q&T 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 16% and the elastic modulus is 210 GPa (30.5 Msi). 38CrMoAlA Q&T 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).
Advantages
- High strength — 880 MPa (128 ksi), better than 90% of steel grades
- High service temperature — 500°C (932 °F), better than 90% 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 Q&T properties
Typical room-temperature values for 38CrMoAlA Q&T — 14 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 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 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 16% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
38CrMoAlA Q&T 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 Q&T conducts electricity at 7.8 % IACS, worse than 58% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (12/100), worse than 53% of steel grades.
Sustainability4
Producing a kilogram of 38CrMoAlA Q&T 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'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.
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
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 — frequently asked
What is 38CrMoAlA Q&T used for?
38CrMoAlA Q&T 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?
38CrMoAlA Q&T 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 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 Q&T 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?
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 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?
38CrMoAlA Q&T 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.
Can FabDigit make parts in 38CrMoAlA Q&T?
Yes — 38CrMoAlA Q&T 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.