1. Material Composition & Key Properties
Q: What defines the chemical/mechanical properties of 38Mn6?
A:
Chemical (wt%):
C: 0.34–0.42 | Mn: 1.30–1.70 | P: ≤0.025 | S: ≤0.025 | Si: 0.15–0.40.
Mechanical:
Yield Strength (σᵧ): ≥490 MPa | Tensile (σₜ): 650–850 MPa.
Elongation (A₅): ≥14% | Hardness: 190–240 HB.
Note: 38Mn6 is a Mn-alloyed medium-carbon steel with excellent hardenability (Jominy test: ≥15mm at 50HRC).
2. Manufacturing & Standards Compliance
Q: How are 38Mn6 tubes produced and certified?
A:
Process: Primarily seamless (hot-rolled + cold-drawn); welded variants require full-body normalization.
Heat Treatment: Quenching & tempering (Q&T) mandatory (880°C oil quench + 550–650°C temper).
Standard Scope: EN 10297-1 for high-pressure mechanical components (e.g., hydraulic cylinders).
3. Dimensional Tolerances
Q: What tolerances apply to 38Mn6 tubes?
A:
| Parameter | Tolerance | Criticality |
|---|---|---|
| OD (D) | ±0.8% (min ±0.4 mm) | Ensures interference fits |
| Wall Thickness | ±8% (min ±0.4 mm) | Critical for burst pressure |
| Straightness | ≤1.2 mm/m | Vital for dynamic load parts |
4. Applications & Limitations
Q: Where is 38Mn6 typically used?
A:
High-Pressure Systems: Hydraulic cylinders (≤800 bar), gas storage cylinders.
Automotive: Axle tubes, torsion bars (Q&T variants).
Avoid:
Temperatures >500°C (risk of temper embrittlement).
Sour service (H₂S) without ISO 15156-compliant coatings.
5. Quality Validation & Certifications
Q: How is quality assured?
A:
Mandatory Tests:
Tensile (EN ISO 6892-1) | Impact (ISO 148-1 at -20°C).
NDT: 100% ultrasonic (EN 10246-1) + magnetic particle (ISO 10893-8).
Certifications: EN 10204 3.2 | PED 2014/68/EU (Category III).
