Made to Your Drawing
Specify head shape, drive, thread, material and finish. We review the drawing and manufacturing requirements before quotation.
GB/T 1231 Structural Bolt Assembly
GB/T 1231
Specifications
| standard | GB/T 1231 |
| diameter | M12–M30 |
| grade | 10.9S |
| material | 20MnTiB / 35CrMo |
| thread | Metric Coarse |
| finish | Black Oxide / Zinc Flake |
| MOQ | 100 sets |
| custom | Available |
Available Sizes
M12M16M20M22M24M27M30
Materials
20MnTiB35CrMo42CrMo
Surface Treatment
Black OxideZinc Flake
Applications
Steel StructuresBridgesIndustrial BuildingsPower Plants
Mechanical Properties
10.9S
Related Products
High-Strength Fastener Coatings: Hydrogen Embrittlement Review
Look beyond coating appearance
Hydrogen embrittlement can cause delayed failure after assembly. Acid cleaning and electroplating can introduce hydrogen into susceptible fasteners. A clean appearance or completed assembly does not establish that this risk has been controlled.
Sources: High-Strength Fastener Coatings: Hydrogen Embrittlement Review — Bossard
Specify the complete coating process
Provide the fastener material and property requirements alongside the coating specification. Ask for a process review, applicable standards and documented controls. Treat hydrogen relief as a qualified process requirement, rather than an automatic guarantee against failure.
Confirm records before batch approval
Agree on process records, required testing and sample approval before manufacture. Keep corrosion protection, thread fit and assembly requirements in the same review. Final process selection depends on the product and application; this article supplies an RFQ checklist, not a blanket coating approval.
Related Products
GB/T 5782 Hex Head Bolt
Standard hex head bolt per GB/T 5782, widely used in general engineering and structural connections.
DIN 931 Hex Head Bolt
Partial thread hex head bolt per DIN 931 (ISO 4014), the most widely used bolt standard internationally.
DIN 933 Full Thread Hex Bolt
Full thread hex head bolt per DIN 933 (ISO 4017), fully threaded for through-bolt connections.
More guides
Surface Treatment Comparison: Zinc Plating vs HDG vs Zinc Flake
Compare coating processes, thread fit and hydrogen-embrittlement considerations before requesting a fastener quotation.
Understanding GB/T 32076.7: High Strength Bolt Assemblies for Steel Structures
A purchasing guide to the M39–M64 scope, assembly requirements and documentation for GB/T 32076.7.
Custom Fastener RFQ Checklist for Factory Bulk Orders
Prepare drawings, acceptance requirements and delivery information so a custom fastener enquiry can be reviewed efficiently.
Request a Quote
Specify your requirement
Your selections will be carried into the RFQ form.