This article's table of contents introduction:
- Material Identification: Q345 (Now Q355 in GB/T 1591-2018)
- Chemical Composition (Wt%) – Delivery Standard
- Mechanical Properties (Delivery Condition)
- Fragment Sourcing & Delivery Specs
- Application-Specific Notes for SWSI Material Handling Fan
- Summary Delivery Checklist for Q345 Fragments:
This is a specific and technical request. It sounds like you are asking for fragment-level material specification details for the Q345 steel used in an Extractor Fan (specifically an SWSI - Single Width, Single Inlet - Material Handling Fan).
Here is the breakdown of the material delivery requirements and specifications for the Q345 steel fragments used in this application.
Material Identification: Q345 (Now Q355 in GB/T 1591-2018)
- Old Standard: GB/T 1591-2008 (Q345)
- New Standard: GB/T 1591-2018 (Q355) Note: Q345 has been replaced by Q355, but "Q345" is still widely used in technical specs, especially for legacy or non-critical structural repairs.
- Grade: Q345B (most common for fan construction; Q345C for low-temp environments)
- Type: Low Alloy High Strength Structural Steel
Chemical Composition (Wt%) – Delivery Standard
For Fragment Material Delivery (i.e., small pieces, cut-offs, or test samples), you must ensure the composition matches the parent material.
| Element | Q345A | Q345B | Q345C (for cold climates) |
|---|---|---|---|
| C | ≤0.20 | ≤0.20 | ≤0.18 |
| Si | ≤0.50 | ≤0.50 | ≤0.50 |
| Mn | 00 - 1.70 | 00 - 1.70 | 00 - 1.70 |
| P | ≤0.035 | ≤0.030 | ≤0.030 |
| S | ≤0.040 | ≤0.030 | ≤0.030 |
| V, Nb, Ti | Added if required | Added if required | Added if required |
Key for Extractor Fan: Q345B is typical. Avoid Q345A for fan housings due to stricter P/S limits.
Mechanical Properties (Delivery Condition)
For the fragments (assuming thickness ≤ 16mm):
- Yield Point (ReL): ≥ 345 MPa (50,000 PSI) - This is the minimum. Fragments must be tested if used for critical weld repairs.
- Tensile Strength (Rm): 470 - 630 MPa (68,000 - 91,000 PSI)
- Elongation (A): ≥ 20-21%
- Impact Test:
- Q345B: 34 J @ 20°C (Ambient)
- Q345C: 34 J @ 0°C (Cold weather extractor)
Why this matters for a Material Handling Fan: The fan handles dust, shavings, or bulk solids. The material must resist abrasion (hardness) and fatigue (toughness).
Fragment Sourcing & Delivery Specs
Since you specified "Fragment Material Delivery" (likely for repairs, spares, or small custom parts):
| Requirement | Standard / Specification |
|---|---|
| Source | Plate, Sheet, or Sectional steel fragments. No re-rolled scrap. |
| Surface | Free from cracks, laps, laminations (>2mm deep). Blast-cleaned if for weld repair. |
| Edge Condition | Factory sheared or flame-cut edges deburred. |
| Dimensional Tolerance | Per GB/T 709 (for plates) or per fan OEM drawing. |
| Certification | Mill Test Certificate (MTC) per EN 10204 Type 2.2 or 3.1 (if fragments are from a larger certified lot). |
Application-Specific Notes for SWSI Material Handling Fan
- Corrosion Margin: If the fan extracts wet air or condensing vapor, specify Q345NH (Weathering Steel) instead of standard Q345.
- Abrasion: For heavy dust (e.g., cement, grain), the fragments should be Q345 + Hardox liner, not bare Q345.
- Weldability: Q345 has a Carbon Equivalent (Ceq) of approximately 0.44. Fragments supplied for repair welding may require pre-heating (100-150°C) if thickness > 25mm.
Summary Delivery Checklist for Q345 Fragments:
- Material: Q345B (GB/T 1591)
- Dimension: As per fan housing repair drawing (e.g., 200x150mm fragments, 10mm plate).
- Condition: As-rolled (normalized for thick sections > 40mm).
- Marking: Each fragment shall be stamped with "Q345B" and Heat No. if traceability is required.
- Quantity: 5 pieces (or as specified) for fit-up / weld repair.
