Q195 is a Chinese standard (GB/T) carbon structural steel grade. The "Q" denotes its Yield Strength (Q from Qu fu dian, meaning yield point), and "195" indicates that its minimum yield strength is 195 MPa.
It is a mild steel with low carbon content, offering good ductility, weldability, and formability. While not as strong as grades like Q235 or Q345, its excellent plasticity makes it suitable for applications where bending, forming, or welding is required without high strength demands.
Key Characteristics:
Standard: GB/T 700 (Carbon Structural Steels)
Yield Strength (σs): ≥ 195 MPa
Tensile Strength (σb): 315 - 430 MPa
Elongation (δ5): ≥ 33% (This high value confirms its good ductility)
Applications: Widely used for low-pressure fluid delivery, fencing, scaffolding, furniture, greenhouse frames, and general structural parts.
Q195 Steel Pipe Product Parameters & Data Tables
Q195 is primarily used to manufacture Welded Steel Pipes (e.g., ERW pipes). It is less common for seamless pipes, which typically use grades like 10# or 20# steel.
1. Common Specifications & Dimensions
Q195 steel pipes are available in a wide range of sizes.
| Parameter | Typical Range / Common Options | |
|---|---|---|
| Production Process | ERW (Electric Resistance Welded) is most common. | |
| Outer Diameter (OD) | 6 mm ~ 630 mm (1/4" ~ 24") | |
| Wall Thickness (WT) | 0.5 mm ~ 12.7 mm (SCH10 ~ SCH80, or directly in mm) | |
| Length | Random Length (RLL): 4m ~ 12m, or Fixed Length (e.g., 6m) |
2. Mechanical Properties Table (Typical Values)
This table summarizes the key mechanical properties as per the standard.
| Property | Symbol | Value | Unit | Note |
|---|---|---|---|---|
| Yield Strength | σs | ≥ 195 | MPa (N/mm²) | Minimum requirement |
| Tensile Strength | σb | 315 - 430 | MPa (N/mm²) | Must fall within this range |
| Elongation | δ5 | ≥ 33 | % | Measured on a gauge length 5x the diameter |
| Hardness | HB | ≤ 131 | - | Brinell Hardness |
3. Chemical Composition Table (GB/T 700 Standard)
The chemical composition (by weight percentage) is crucial for determining its properties.
| Element | Standard Requirement (%) | Typical Value (%) | Note |
|---|---|---|---|
| Carbon (C) | ≤ 0.12 | 0.06 - 0.09 | Low carbon ensures good weldability. |
| Manganese (Mn) | ≤ 0.50 | 0.25 - 0.40 | |
| Silicon (Si) | ≤ 0.30 | 0.10 - 0.20 | |
| Sulfur (S) | ≤ 0.050 | ≤ 0.035 | Impurities, controlled for weldability. |
| Phosphorus (P) | ≤ 0.045 | ≤ 0.035 | Impurities, controlled for toughness. |
| Iron (Fe) | Balance | Remainder is iron and negligible impurities. |
Note: The "Grade A" designation (Q195A) may have slightly different deoxidation requirements but similar composition.
Comparison with International Equivalents
Q195 is often compared to similar mild steel grades from other international standards. These are not exact equivalents but are often used for similar applications.
| Standard | Grade | Yield Strength (Min) | Tensile Strength | Key Similarity |
|---|---|---|---|---|
| Chinese (GB/T) | Q195 | 195 MPa | 315-430 MPa | Base Grade |
| ASTM (USA) | A36 | 250 MPa | 400-550 MPa | Common structural steel, slightly stronger. |
| ASTM (USA) | A513 (Type 1) | Varies | Varies | Typical grade for ERW mechanical tubing. |
| JIS (Japanese) | SS330 (SS34) | 205 MPa | 330-430 MPa | Very close equivalent in terms of strength. |
| EN (European) | S185 | 185 MPa | 300-500 MPa | Very similar strength and application. |
| DIN (German) | St33 | 190-220 MPa | 320-370 MPa | Similar mild steel grade. |
Common Standards for Q195 Pipes
Pipes made from Q195 are produced under various GB standards based on their intended use:
GB/T 3091: Welded steel pipes for low-pressure fluid conveyance (e.g., water, gas, air).
GB/T 13793: Welded steel pipes for furnace and heat exchange.
GB/T 6728: Welded steel hollow sections for structural purposes.
Summary of Advantages and Limitations
Advantages:
Cost-Effective: One of the most economical steel grades.
Easy to Process: Excellent for cold bending, cutting, and welding.
Ductile: Withstands deformation without cracking.
Limitations:
Low Strength: Not suitable for high-stress structural applications or high-pressure systems.
Limited Corrosion Resistance: Requires galvanizing, painting, or other coatings for outdoor or corrosive environments.
Not for Precision Parts: Properties are less tightly controlled than in alloy steels.
In summary, Q195 steel pipe is a versatile, general-purpose mild steel tube chosen for its formability and low cost in non-critical applications. Its parameters make it a staple in construction, furniture, and low-pressure fluid systems.
