Low-alloy structural steel materials suitable for medium and high-strength structural parts, welded parts, construction machinery parts, steel structural parts, brackets, frames, bases, load-bearing plates, and low-cost, high-strength metal structural parts.
Q345 is a commonly used low-alloy, high-strength structural steel with good strength, plasticity, toughness, weldability, and comprehensive structural properties. Compared to Q235, Q345 has higher strength and is suitable for manufacturing welded structural parts with higher load-bearing requirements, construction machinery parts, steel structural parts, brackets, bases, frames, bridge components, vehicle structural parts, and medium to high load metal parts. It costs less than stainless steel and most high-strength alloy steels, but has poor corrosion resistance and usually requires surface protection such as galvanizing, painting, powder spraying, blackening, phosphating, or rust prevention.
By focusing on application scenarios, boundaries of advantages, and non-recommended scenarios, it helps sales, customer service, and quoting staff quickly determine whether the material meets current part requirements.
Strength higher than Q235, good overall structural performance, good weldability, good load-bearing capacity, relatively controllable material costs, suitable for large welded structures, construction machinery and steel structural parts, wide material sources, and capable of cutting, bending, welding, machining, and surface protection treatments.
Construction machinery structural parts, equipment frames, welded bases, load-bearing supports, steel structural parts, connecting plates, mounting plates, vehicle structural parts, bridge components, mechanical frames, load-bearing sheet metal parts, fixture base plates, heavy-duty support parts, low-alloy high-strength welded parts, medium and high load metal structural parts.
Highly corrosive environmental parts, parts exposed outdoors for long periods without rust prevention, food direct contact parts, medical implants, high-precision high-speed transmission parts, high-hardness wear-resistant parts, highly elastic snap-fit parts, ultra-lightweight parts, parts requiring stainless steel appearance, and metal parts requiring maintenance-free corrosion resistance.
The following parameters come from product information and material knowledge fields, used for design review, quotation communication, and preliminary judgment before material selection.
| Material positioning | Low-alloy structural steel materials suitable for medium and high-strength structural parts, welded parts, construction machinery parts, steel structural parts, brackets, frames, bases, load-bearing plates, and low-cost, high-strength metal structural parts. |
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| Precision performance | The Q345 is suitable for laser cutting, plasma cutting, flame cutting, bending, welding, drilling, tapping, and general CNC machining. The accuracy of sheet metal and welded parts is affected by plate thickness, cutting method, bending and springback, welding thermal deformation, assembly fixtures, and surface treatment. Compared to CNC precision parts, Q345 is better suited for structural dimensions and engineering manufacturing. Precision hole positions, positioning surfaces, and assembly surfaces are recommended for post-processing or separate tolerance control. |
| Dimensional tolerances | For ordinary laser cutting or stamping, dimensional tolerances can be referenced as ±0.10mm-±0.30mm; after bending, the overall dimensional tolerance can be ±0.30mm-±1.00mm. Welded structural parts may need to be evaluated at ±0.50mm-±2.00mm. Dimensional deviations may be greater when using thick plate flame cutting or plasma cutting. If CNC machining is used, conventional dimensional tolerances can refer to ±0.05mm-±0.20mm. These values are standard reference ranges and do not guarantee absolute tolerances for all structures. In practice, they must be confirmed based on board thickness, dimensions, structure, processing methods, and post-processing. |
| Minimum Wall Thickness | Q345 is commonly used in the form of steel plates, profiles, steel pipes, and structural components. Standard thin plates can be used in thicknesses of 1.0mm, 1.5mm, 2.0mm, etc.; For ordinary structural parts, it is recommended not to be less than 2.0mm; for areas requiring welding, tapping, bearing assembly force, or structural loads, appropriate thickening is recommended. For large-scale load-bearing structures, it is not recommended to use overly thin sheets for direct load-bearing and should be designed with reinforcing ribs, folded edges, or profile structures. |
| Recommended wall thickness | For ordinary sheet metal parts and protective covers, 1.5mm-3.0mm is recommended; for ordinary brackets, connecting plates, mounting plates, and welded parts, 3.0mm-6.0mm is recommended; for frames, bases, load-bearing structures, and construction machinery, it is recommended to select larger plate thickness according to the load, and to improve rigidity and load-bearing capacity through reinforcing ribs, welded frameworks, profile combinations, and structural optimization. |
| Minimum aperture | Laser cutting aperture is recommended to be no less than one time the plate thickness, and stable design suggests a hole diameter of no less than 1.5mm-2.0mm. Small holes, dense holes, and holes near bending lines or welds on thick plates are prone to deformation, slag accumulation, or burrs. Screw holes, positioning holes, and assembly holes should be reasonably allowable based on board thickness, fastener specifications, coating thickness, and processing method. For precision holes, it is recommended to drill, ream, or bore the holes. |
| Assembly clearance | For ordinary structural assemblies, it is recommended to reserve 0.20mm-0.50mm on one side; for thick plates, welded parts, and large structural parts, it is recommended to reserve more adjustment space based on welding deformation and manufacturing errors. Insertion, slot, and multi-piece welded assembly structures should be enlarged by combining plate thickness, cutting errors, and coating thickness to enlarge gaps. If powder coating, painting, galvanizing, or electroplating is required later, additional consideration of surface treatment thickness should be taken into account to avoid over-tight assembly or interference with hole positions. |
| Detailed performance | Q345 is suitable for making holes, grooves, folded edges, reinforcement ribs, welded structures, bearing plates, mounting holes, connection holes, lifting holes, and general engineering structural details. Passing through small slots, sharp corners, and narrow bridges requires consideration of burr cutting, thermal deformation, welding deformation, and processing costs. Text, logos, and markings are recommended to be achieved through laser marking, stamping, nameplates, inkjet coding, etching, or silkscreen printing. It is not recommended to design overly fine mechanical cutting text on thick plates. |
| Surface effect | The original surface of Q345 is usually gray-black, silver-gray, or steel with oxide scale, and may have rolling textures, oil stains, rust spots, or cutting marks. After sandblasting or shot blasting, a uniform rough substrate is obtained, suitable for painting or powder spraying; After galvanizing, it achieves a silver-white or gray-silver rust-resistant appearance; After painting or powder spraying, it can achieve multiple colors and provide good outdoor protection. If long-term appearance stability is desired, galvanizing, powder coating, painting, or switching to stainless steel are recommended. |
Based on material characteristics and suitable product ranges, customer needs are broken down into easier application directions to determine.
Construction machinery structural parts, equipment frames, welded bases, load-bearing supports, steel structural parts, connecting plates, mounting plates, vehicle structural parts, bridge components, mechanical frames, load-bearing sheet metal parts, fixture base plates, heavy-duty support parts, low-alloy high-strength welded parts, medium and high load metal structural parts.
Low-alloy structural steel materials suitable for medium and high-strength structural parts, welded parts, construction machinery parts, steel structural parts, brackets, frames, bases, load-bearing plates, and low-cost, high-strength metal structural parts.
Q345 is a low-alloy, high-strength structural steel, with strength and load-bearing capacity usually higher than Q235, making it suitable for welded parts, brackets, frames, and engineering structural components with higher structural strength requirements. It balances certain plasticity, toughness, and weldability, making it suitable for engineering manufacturing and low-cost structural applications. However, Q345 is still a rust-prone steel. Exposed to humidity, salt spray, or outdoor environments, rust will occur, requiring improvements such as galvanizing, painting, powder spraying, blackening, phosphating, or anti-rust oil to improve weather resistance.
Based on wall thickness, hole position, assembly clearance, dimensional tolerances, and material usage risks, determine in advance whether the part structure is suitable for Q345.
Post-processing of Q345 affects appearance, dimensions, hole position, assembly clearance, and usage validation results, and should be explained in advance during quotation, DFM review, and sample confirmation stages.
Post-processing should focus on appearance display, dimensional fitting, connection assembly, and testing verification. Parts involving assembly positions need to be reserved in advance for machining, coating, and trial assembly allowances.
For common issues such as threads, snaps, strength, temperature resistance, and weather resistance, identify in advance whether the material needs to be replaced or if another processing method should be used.
When customer demand exceeds Q345 material boundaries, it is necessary to promptly recommend alternative materials or processing technologies based on strength, temperature resistance, toughness, long-term stability, and mass production goals.
If lower cost and average strength are needed, Q235 is available; If higher strength and better mechanical properties are required, 45# steel, 40Cr, 42CrMo, or higher strength low-alloy steels can be chosen; If better corrosion resistance is required, 304 stainless steel, 316 stainless steel, galvanized steel plate, or weather-resistant steel can be chosen; If lightweight design is needed, you can choose 6061 Aluminum Alloy, 7075, or TC4 Titanium Alloy (Ti-6Al-4V); If high hardness and wear resistance are required, alloy steel, mold steel, or surface hardening materials can be chosen.
If customers need higher load capacity than Q235 while maintaining good weldability and cost advantages, the Q345 is the right choice. If it is just ordinary low-cost sheet metal parts or light-load structures, Q235 may be more economical. If parts need to be used outdoors for extended periods in humid, salt spray, or corrosive environments, it is not recommended to use exposed Q345 directly; stainless steel, galvanized steel, weathering steel, or additional reliable surface protection treatments should be chosen.
After uploading 3D/2D drawings and supplementing materials, quantities, tolerances, surface treatments, and delivery requirements, XPartsLab will provide next steps in 3D printing manufacturability, cost, and delivery pathways.
