Introduction
QT550-5 is a spheroidal graphite iron casting grade covered by GB/T 1348. Typical applications include gear blanks, transmission components, crankshafts and machinery parts.
| Field | Value |
|---|---|
| Designation | QT550-5 |
| Material Type | Cast Iron |
| Sub Type | Ductile Cast Iron |
| Product Form | casting |
Manufacturing Process
Sand Casting
Shell Molding Casting
Lost Foam Casting
Equivalent Materials
Similar Materials
N/A
Reference Standards
| Standard | Standard Title | Edition | Specification | Identifier |
|---|---|---|---|---|
| GB/T 1348 | Spheroidal graphite iron castings | 2019 | QT550-5 | — |
Related Casting Products
Physical Properties
| Property | Value / Unit | Note | Source |
|---|---|---|---|
| Elastic Modulus | 172 GPa | measured at room temperature unless otherwise stated, not an acceptance limit | GB/T 1348 |
| Poisson Ratio | 0.275 | measured at room temperature unless otherwise stated, not an acceptance limit | GB/T 1348 |
| Thermal Conductivity | 34 W/(m·K) | Test at 300 °C; measured at room temperature unless otherwise stated, not an acceptance limit | GB/T 1348 |
| Specific Heat | 515 J/(kg·K) | measured at room temperature unless otherwise stated, not an acceptance limit; Temperature range: 20–500 °C | GB/T 1348 |
| Thermal Expansion | 12.5 ×10⁻⁶/K | measured at room temperature unless otherwise stated, not an acceptance limit; Temperature range: 20–400 °C | GB/T 1348 |
| Density | 7.1 kg/dm³ | measured at room temperature unless otherwise stated, not an acceptance limit | GB/T 1348 |
| Maximum Magnetic Permeability | 1200 µH/m | measured at room temperature unless otherwise stated, not an acceptance limit | GB/T 1348 |
| Hysteresis Loss | 1800 J/m3 | measured at room temperature unless otherwise stated, not an acceptance limit; B = 1 T | GB/T 1348 |
| Electrical Resistivity | 0.52 µΩ·m | measured at room temperature unless otherwise stated, not an acceptance limit | GB/T 1348 |
Chemical Composition
No specified chemical composition limits in GB/T 1348
Heat Treatment
GB/T 1348–2019
Heat treatment may be required under agreed delivery or retesting conditions. No grade-specific heat-treatment temperature or holding schedule is prescribed.
Mechanical Properties
Core Mechanical Properties
Conditions are not identical. Compare each stated condition and applicability separately.
GB/T 1348 — 2019 · Table 1 — Normative
| Property | 30 < t ≤ 60 mm | 60 < t ≤ 200 mm | t ≤ 30 mm |
|---|---|---|---|
| Yield Strength (Rp0.2) | ≥ 330 MPa | ≥ 320 MPa | ≥ 350 MPa |
| Tensile Strength | ≥ 520 MPa | ≥ 500 MPa | ≥ 550 MPa |
| Elongation | ≥ 4 % | ≥ 3 % | ≥ 5 % |
Common specimen condition: Separately cast, cast-on or side-by-side cast sample
Full original column conditions
- 30 < t ≤ 60 mm — Separately cast, cast-on or side-by-side cast sample · 30 < t ≤ 60 mm
- 60 < t ≤ 200 mm — Separately cast, cast-on or side-by-side cast sample · 60 < t ≤ 200 mm
- t ≤ 30 mm — Separately cast, cast-on or side-by-side cast sample · t ≤ 30 mm
- L0 = 5d; GB/T 228.1; Minimum prescribed value
- Separately cast, cast-on or side-by-side cast sample · 30 < t ≤ 60 mm: wall thickness ≤ 60 mm
- Separately cast, cast-on or side-by-side cast sample · 60 < t ≤ 200 mm: wall thickness ≤ 200 mm
- Separately cast, cast-on or side-by-side cast sample · t ≤ 30 mm: wall thickness ≤ 30 mm
GB/T 1348 — 2019 · Table C.1 — Informative
| Property | 30 < t ≤ 60 mm | 60 < t ≤ 200 mm | t ≤ 30 mm |
|---|---|---|---|
| Yield Strength (Rp0.2) | ≥ 310 MPa | ≥ 290 MPa | ≥ 330 MPa |
| Tensile Strength | ≥ 500 MPa | ≥ 450 MPa | ≥ 530 MPa |
| Elongation | ≥ 3 % | ≥ 2 % | ≥ 4 % |
Full original column conditions
- 30 < t ≤ 60 mm — Specimen cut from the casting · 30 < t ≤ 60 mm
- 60 < t ≤ 200 mm — Specimen cut from the casting · 60 < t ≤ 200 mm
- t ≤ 30 mm — Specimen cut from the casting · t ≤ 30 mm
- source designation QT550-5/C; sampling position and acceptance properties subject to agreement; L0 = 5d; GB/T 228.1; Informative minimum guideline, not an unconditional acceptance requirement; Informative reference value; not an acceptance requirement
- Specimen cut from the casting · 30 < t ≤ 60 mm: wall thickness ≤ 60 mm
- Specimen cut from the casting · 60 < t ≤ 200 mm: wall thickness ≤ 200 mm
- Specimen cut from the casting · t ≤ 30 mm: wall thickness ≤ 30 mm
GB/T 1348 — 2019 · Table G.1 — Informative
| Property | Value |
|---|---|
| Shear Strength | 500 MPa |
| Compressive Strength | 840 MPa |
- Annex G informative reference data; measured at room temperature unless otherwise stated, not an acceptance limit; Informative reference value; not an acceptance requirement
Additional Mechanical Properties
Fracture Toughness
GB/T 1348 — 2019 · Table G.1 — Informative
| Property | Value |
|---|---|
| Fracture Toughness (KIC) | 22 MPa√m |
- Annex G informative reference data; measured at room temperature unless otherwise stated, not an acceptance limit; Informative reference value; not an acceptance requirement
Other Mechanical Properties
GB/T 1348 — 2019 · Table G.1 — Informative
| Property | Value |
|---|---|
| Torsional Strength | 500 MPa |
- Annex G informative reference data; measured at room temperature unless otherwise stated, not an acceptance limit; Informative reference value; not an acceptance requirement
Welding Conditions
N/A
Applications
Ductile iron GB/T 1348 Grade QT550-5 is used for gear blanks, transmission components, crankshafts and machinery parts. Such castings are used in industrial drives, agricultural machinery, engines and off-highway equipment. Component selection depends on section size, loading and the required finished surface. Wear performance or fatigue life cannot be inferred from the grade name alone; any surface treatment and associated acceptance requirements must be specified for the actual part.
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Email Us for a QuoteLast Updated: November 6, 2026