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Help CenterFlat Steel & Engineering Flat Steel，Q355B/D、Q460、65Mn、60Si2Mn、Q235B、Q195、45#
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Flat Steel & Engineering Flat Steel，Q355B/D、Q460、65Mn、60Si2Mn、Q235B、Q195、45#NegotiableMOQ: 5 Metric Tons -
Flat Steel & Engineering Flat Steel，Q355B/D、Q460、65Mn、60Si2Mn、Q235B、Q195、45#NegotiableMOQ: 5 Metric Tons
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Flat Steel & Engineering Flat Steel，Q355B/D、Q460、65Mn、60Si2Mn、Q235B、Q195、45#NegotiableMOQ: 5 Metric Tons
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Flat Steel & Engineering Flat Steel，Q355B/D、Q460、65Mn、60Si2Mn、Q235B、Q195、45#NegotiableMOQ: 5 Metric Tons
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Flat Steel & Engineering Flat Steel，Q355B/D、Q460、65Mn、60Si2Mn、Q235B、Q195、45#NegotiableMOQ: 5 Metric Tons
1. Basic Definition
Flat steel (also known as flat iron) is a long strip steel with a rectangular cross-section and slightly blunted edges, belonging to a simple cross-section section steel with a width-to-thickness ratio generally greater than 3. According to national standard definition, it features a width of 12–300mm, a thickness of 3–60mm, and a standard length of 6m/12m, with customized lengths available.
2. Core Classification
2.1 Classification by Production Process
Hot Rolled Flat Steel: Formed by high-temperature rolling, featuring good strength and toughness, rough surface and low cost, which is the preferred choice for general structural projects. Compliant with GB/T 704-2016.
Cold Drawn Flat Steel: Formed by normal-temperature cold drawing, with high dimensional accuracy and smooth surface, suitable for precision mechanical parts. Compliant with YB/T 037-1993.
Forged Flat Steel: Formed by forging, with dense internal structure and ultra-high strength, applied for heavy-load and special working conditions with relatively high cost.
2.2 Classification by Main Material
Carbon Structural Steel: Q235B (most widely used with high cost performance), Q195, 45#. It features moderate strength and excellent weldability and processability.
High-Strength Low-Alloy Steel: Q355B/D, Q460. It boasts high strength, low temperature resistance and impact resistance, widely used in bridges, cranes and shipbuilding industries.
Special Materials: Spring steel (65Mn, 60Si2Mn) and tool steel, applied for manufacturing springs, cutting tools and other special parts.
2.3 Classification by Application
General Flat Steel: Used for building structures, stairs, supports and guardrails.
Spring Flat Steel: Used for automobile leaf springs and mechanical elastic components.
Tool Flat Steel: Used as blanks for cutting tools, molds and bench work tools.
3. Specification Parameters (National Standard GB/T 704)
3.1 Dimension Representation
Expressed as Width × Thickness × Length (mm), e.g. 50×5×6000 (width 50mm, thickness 5mm, length 6m).
3.2 Common Dimensions (Width × Thickness, mm)
Width: 12, 16, 20, 25, 30, 40, 50, 60, 80, 100, 120, 150, 200
Thickness: 3, 4, 5, 6, 8, 10, 12, 14, 16, 20, 25, 30
Length: Standard fixed lengths of 6m/12m, customized lengths from 3m to 15m are available.
3.3 Weight Calculation
Theoretical Weight (kg/m) = 0.00785 × Width × Thickness (mm)
Example: 50×5 flat steel → 0.00785×50×5 = 1.9625 kg/m
4. Production Process (Mainly Hot Rolling)
1. Raw Material: Qualified continuous casting square billets or round billets. 2. Heating: Heated to 1100–1250℃ for uniform austenitization. 3. Rolling: Rolled through multiple passes to form a standard rectangular cross-section. 4. Cooling: Air cooling or water cooling to control internal structure and hardness. 5. Cutting: Fixed-length cutting at 6m or 12m. 6. Finishing: Straightening, derusting, quality inspection and packaging.
5. Performance Characteristics
5.1 Advantages
Flexible Specifications: Customizable thickness, width and length reduce secondary cutting and improve material utilization by 1–5% compared with steel plates.
Excellent Processability: Easy for welding, drilling, bending and cutting, suitable for various secondary processing.
Stable Load-Bearing Capacity: The flat cross-section disperses load evenly and delivers better bending resistance than round steel of the same weight.
High Cost Performance: Mature hot rolling technology ensures lower price than steel plates and other section steels.
5.2 Surface Quality & Dimensional Accuracy
Hot Rolled Type: With surface oxide scale, surface roughness Ra 25–100μm, dimensional tolerance ±0.5–1mm.
Cold Drawn Type: Bright and smooth surface, surface roughness Ra 1.6–6.3μm, dimensional tolerance ±0.1–0.3mm.
6. Executive Standards
Hot Rolled Flat Steel: GB/T 704-2016 (Dimensions, shape, weight and allowable deviation)
Carbon Steel: GB/T 700-2006 (Q235), GB/T 699-2015 (45#)
Low-Alloy Steel: GB/T 1591-2018 (Q355)
7. Main Application Scenarios
1. Building Steel Structure: Roof frames, stairs, tread plates, supports, guardrails and curtain wall connectors.
2. Mechanical Manufacturing: Equipment frames, bases, backing plates, guide rails, gear blanks and tool cutting edges.
3. Automobile & Transportation: Body frames, bumpers, leaf springs, trailer chassis and railway accessories.
4. Engineering & Municipal Works: Bridge supports, street lamp base plates, cable trench supports and manhole cover frames.
8. Quality Inspection
1. Visual Inspection: No cracks, folds, scabs or serious rust on the surface, and no burrs on edges.
2. Dimensional Inspection: Width and thickness measured by caliper, length measured by tape measure, all deviations shall comply with GB/T 704 standard.
3. Mechanical Property Test: Tensile test (yield strength, tensile strength, elongation) and bending test (no crack after 180° bending).
4. Material Analysis: Spectral or chemical analysis to detect the content of C, Mn, Si, P, S and other elements.
9. Packaging & Delivery
Packaging: Bundled packing (50–200 pieces per bundle) with labels marked with specifications, material, batch number and production date at both ends.
Delivery Standard: Delivered by theoretical weight or actual weight, with official quality certificate including furnace number, chemical composition, mechanical properties and executive standards.
Delivery Time: 5-7 working days
10. Selection Suggestions
1. General structural projects: Choose Q235B hot rolled flat steel for lowest cost and excellent processability.
2. Precision mechanical parts: Choose 45#/Q355 cold drawn flat steel for high accuracy and smooth surface.
3. Heavy-load & low-temperature working conditions: Choose Q355D low-alloy flat steel.
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