Torx Countersunk Screws (GB/T 2673-2000 / ISO 14581) — Steel Class 4.8, Bright Zinc Plated

FULLERKREG Torx countersunk flat-head screws in low carbon steel C1008, Class 4.8 with bright zinc plating and trivalent chromium passivation (Zinc Cr3) are manufactured to GB/T 2673-2000 and ISO 14581 standards. Featuring a 90° countersunk head with an internal Torx (TX) drive, these screws deliver reliable torque transmission, reduced cam-out risk, and a flush-mount finish. The bright zinc Cr3 coating provides a clean silver appearance with solid corrosion protection, fully RoHS and ELV compliant — free of hexavalent chromium (Cr6+). Ideal for general-purpose assemblies, light structural applications, furniture, electronics enclosures, and sheet metal work where cost-effective performance is required.

Product Specifications

Attribute	Detail
Product Name	Torx Countersunk Flat Head Screws
Standard	GB/T 2673-2000 / ISO 14581
Drive Type	Torx (TX) Internal Drive
Head Type	Countersunk (Flat Head), 90° included angle
Material	Low Carbon Steel C1008
Surface Treatment	Bright Zinc Plated, Trivalent Chromium Passivation (Cr3 / Cr-III)
Coating Compliance	RoHS compliant, ELV compliant — Cr6+ free
Strength Grade	Class 4.8
Size Range	M2 – M10
Length Range	3 mm – 80 mm
Brand	FULLERKREG

Product Photo Gallery

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Dimensional Drawing

Per GB/T 2673-2000 / ISO 14581 — Countersunk head with 90° included angle, Torx recess depth t, head diameter dk, head height k, thread pitch p.

• Head angle: 90° (±1°)
• Torx recess: TX drive per ISO 10664
• Thread: Metric coarse thread per ISO 68-1
• Thread tolerance: 6g
• Head tolerance: h13

Dimensional Data

Thread d	Pitch p (mm)	TX Drive	Head Dia. dk max (mm)	Head Dia. dk min (mm)	Head Height k max (mm)	Head Height k min (mm)	Recess Depth t min (mm)	Recess Depth t max (mm)	Min. Thread Length b (mm)	Unit Weight (g / 100 pcs)
M2	0.40	TX6	3.80	3.50	1.20	0.96	0.70	1.00	12	—
M2.5	0.45	TX8	4.70	4.40	1.50	1.21	0.85	1.20	14	—
M3	0.50	TX10	5.60	5.30	1.65	1.35	1.00	1.40	16	—
M4	0.70	TX20	7.50	7.14	2.20	1.86	1.30	1.80	20	—
M5	0.80	TX25	9.20	8.84	2.50	2.16	1.50	2.10	22	—
M6	1.00	TX30	11.00	10.57	3.00	2.61	1.80	2.50	24	—
M8	1.25	TX40	14.50	14.07	4.00	3.54	2.30	3.20	28	—
M10	1.50	TX50	18.00	17.57	5.00	4.54	2.80	3.80	32	—

* All dimensions in mm. Tolerances per GB/T 2673-2000 / ISO 14581. Unit weight (g/100 pcs) to be updated upon batch confirmation.

Standard Length Range by Diameter

Thread	Available Lengths (mm)
M2	3, 4, 5, 6, 8, 10, 12, 16, 20
M2.5	4, 5, 6, 8, 10, 12, 16, 20, 25
M3	4, 5, 6, 8, 10, 12, 16, 20, 25, 30
M4	5, 6, 8, 10, 12, 16, 20, 25, 30, 35, 40
M5	6, 8, 10, 12, 16, 20, 25, 30, 35, 40, 45, 50
M6	8, 10, 12, 16, 20, 25, 30, 35, 40, 45, 50, 55, 60
M8	10, 12, 16, 20, 25, 30, 35, 40, 45, 50, 55, 60, 70, 80
M10	16, 20, 25, 30, 35, 40, 45, 50, 55, 60, 70, 80

Selection Guide

Requirement	Recommendation
General-purpose / light structural assembly	Class 4.8 low carbon steel is cost-effective and widely available for standard load applications
Flush surface finish required	Use countersunk head; ensure countersink angle matches 90°
Anti-cam-out / reliable drive	Torx (TX) drive preferred over Phillips or slotted for consistent torque application
RoHS / ELV compliance required	Zinc Cr3 (trivalent chromium) is fully Cr6+-free and compliant with EU RoHS & ELV directives
Indoor / light outdoor environment	Bright zinc Cr3 provides 72–120 h salt spray resistance — suitable for sheltered or indoor use
Furniture / electronics / sheet metal	Class 4.8 with bright zinc finish is the standard choice for non-critical assemblies
High-load / structural application	Upgrade to Class 10.9 alloy steel for higher clamping force requirements
Corrosive / marine environment	Consider stainless steel A2 or A4 grades instead

Class 4.8 vs. Other Strength Grades

Property	Class 4.8	Class 8.8	Class 10.9
Material	Low Carbon Steel C1008	Medium Carbon / Alloy Steel	Alloy Steel 10B21 (Q&T)
Min. Tensile Strength (Rm)	420 MPa	800 MPa	1040 MPa
Min. Yield Strength (Rp0.2)	340 MPa	640 MPa	940 MPa
Hardness (Vickers)	130–220 HV	250–320 HV	320–380 HV
Typical Application	General / light duty	General structural	High-strength mechanical
Cost	Lowest	Medium	Higher

Standard Reference

GB/T 2673-2000 is the Chinese national standard for countersunk head screws with Torx recess, technically equivalent to ISO 14581:2011. Key parameters defined by the standard:

• Head angle: 90° included angle (±1°)
• Drive recess: Torx (TX) per ISO 10664
• Thread: ISO metric coarse, tolerance class 6g
• Material: Low carbon steel C1008
• Strength class: 4.8 per ISO 898-1 (min. tensile strength 420 MPa)
• Surface: Bright zinc electroplating with trivalent chromium passivation (Cr3) — RoHS & ELV compliant, Cr6+-free

Material & Mechanical Properties

Property	Class 4.8 Value
Material	Low Carbon Steel C1008
Min. Tensile Strength (Rm)	420 MPa
Min. Proof Load Stress (Sp)	310 MPa
Min. Yield Strength (Rp0.2)	340 MPa
Min. Elongation (A)	14%
Hardness (Vickers)	130–220 HV
Surface Treatment	Bright Zinc Electroplating + Trivalent Chromium Passivation (Cr3)
Salt Spray Resistance	72–120 h (neutral salt spray, per ISO 9227)
Coating Thickness	5–12 μm (zinc layer)
Environmental Compliance	RoHS compliant, ELV compliant — Cr6+ free
Magnetic	Yes (ferromagnetic)

Packaging & Supply

Item	Detail
Standard Pack	100 pcs / bag, 1,000 pcs / box (varies by size)
MOQ	100 pcs (standard sizes); custom quantities available
Labeling	Size, standard, material, grade, surface, quantity — FULLERKREG brand label
Custom Packaging	Available on request (OEM / private label)
Lead Time	In-stock items: 1–3 business days; custom orders: 7–15 business days

Why FULLERKREG

🏭 Factory Direct — Manufactured in-house with full process control, no middlemen.
📐 Standard Compliant — Strictly per GB/T 2673-2000 / ISO 14581 and ISO 898-1; third-party inspection available.
🔬 Material Certified — Mill certificates (MTC) provided; C1008 steel composition verified per batch.
✅ RoHS & ELV Compliant — Zinc Cr3 surface is fully Cr6+-free; compliance documentation available on request.
📦 Bulk Ready — Wholesale quantities from 100 pcs to millions; competitive tiered pricing.
🌍 Global Shipping — Export experience to 30+ countries; DDP / FOB / EXW terms available.
🔧 Technical Support — Engineering team available for selection guidance, drawings, and custom specs.