Stainless Hex Head Bolts (Partial Thread)
| Standard | DIN 931 · ISO 4014 · ASTM F593 |
|---|---|
| Material | SS304 / SS316 |
| Strength Grade | A2-70 / A4-80 |
| Size Range | M6-M36 |
| Surface Treatment | Passivated |
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Product Description
Product Description & Key Specifications
DIN 931 / ISO 4014 partial-thread stainless hex head bolts are supplied in SS304 / SS316 and A2-70 / A4-80 grades, with common sizes from M6-M36, passivated finish and matching stainless nuts and washers for project procurement.
Stainless hex head bolts with partial thread are designed for bolted joints where the unthreaded shank passes through part of the clamped area and the threaded section engages with a nut or tapped component. This geometry is commonly selected when the drawing defines a grip length, when thread exposure inside the joint should be reduced, or when the assembly needs better alignment between the bolt shank, washer stack and connected parts. Compared with full-thread bolts, partial-thread bolts can provide a cleaner bearing area and are often preferred for structural brackets, frames, mounting rails and equipment assemblies that see repeated service loads.
Passivation is used to improve the stainless surface condition after forming, machining or thread production. It helps remove free iron contamination and supports long-term corrosion resistance when the bolts are installed with compatible stainless nuts and washers. Eternal Fastener can supply bolts only or complete bolt-nut-washer sets according to DIN / ISO requirements, drawings, project bills of material and export packaging needs.
| Product type | Stainless hex head bolts, partial thread |
|---|---|
| Standards | DIN 931 / ISO 4014 / ASTM F593 reference |
| Material | SS304 / SS316 |
| Strength grade | A2-70 / A4-70 / A4-80 |
| Size range | M6-M36, with length and thread length confirmed by order |
| Common models | M8 x 40, M10 x 50, M12 x 60, M16 x 80, M20 x 100, or drawing-based grip length |
| Thread type | Metric coarse thread, partial thread |
| Surface finish | Passivated stainless surface |
| Supply form | Bolts only or matched bolt-nut-washer sets |
| Documentation | CoC, material certificate and dimensional report on request |
Dimensions & SpecificationsDIN 931 / ISO 4014
Technical Drawing
Dimensional Table
| Parameter | M1.6 | M2 | M2.5 | M3 | M3.5 | M4 | M5 | M6 | M7 | M8 | M10 | M12 | M14 | M16 | M18 | M20 | M22 | M24 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| P | 0.35 | 0.4 | 0.45 | 0.5 | 0.6 | 0.7 | 0.8 | 1 | 1 | 1.25 | 1.5 | 1.75 | 2 | 2 | 2.5 | 2.5 | 2.5 | 3 |
| da/max | 2 | 2.6 | 3.1 | 3.6 | 4.1 | 4.7 | 5.7 | 6.8 | 7.8 | 9.2 | 11.2 | 13.7 | 15.7 | 17.7 | 20.2 | 22.4 | 24.4 | 26.4 |
| ds/max | 1.6 | 2 | 2.5 | 3 | 3.5 | 4 | 5 | 6 | 7 | 8 | 10 | 12 | 14 | 16 | 18 | 20 | 22 | 24 |
| ds/min | 1.46 | 1.86 | 2.36 | 2.86 | 3.32 | 3.82 | 4.82 | 5.82 | 6.78 | 7.78 | 9.78 | 11.73 | 13.73 | 15.73 | 17.73 | 19.67 | 21.67 | 23.67 |
| e/min | 3.41 | 4.32 | 5.45 | 6.01 | 6.58 | 7.66 | 8.79 | 11.05 | 12.12 | 14.38 | 18.9 | 21.1 | 24.49 | 26.75 | 30.14 | 33.53 | 35.72 | 39.98 |
| k/max | 1.22 | 1.52 | 1.82 | 2.12 | 2.52 | 2.92 | 3.65 | 4.15 | 4.95 | 5.45 | 6.58 | 7.68 | 8.98 | 10.18 | 11.72 | 12.72 | 14.22 | 15.22 |
| k/min | 0.98 | 1.28 | 1.58 | 1.88 | 2.28 | 2.68 | 3.35 | 3.85 | 4.65 | 5.15 | 6.22 | 7.32 | 8.62 | 9.82 | 11.28 | 12.28 | 13.78 | 14.78 |
| r/min | 0.1 | 0.1 | 0.1 | 0.1 | 0.1 | 0.2 | 0.2 | 0.25 | 0.25 | 0.4 | 0.4 | 0.6 | 0.6 | 0.6 | 0.6 | 0.8 | 0.8 | 0.8 |
| s/max | 3.2 | 4 | 5 | 5.5 | 6 | 7 | 8 | 10 | 11 | 13 | 17 | 19 | 22 | 24 | 27 | 30 | 32 | 36 |
| s/min | 3.02 | 3.82 | 4.82 | 5.32 | 5.82 | 6.78 | 7.78 | 9.78 | 10.73 | 12.73 | 16.73 | 18.67 | 21.67 | 23.67 | 26.67 | 29.67 | 31.61 | 35.38 |
Engineering references
Technical resources
Review the applicable dimensions, drawing and standard relationship before confirming the ordered specification.02
Selection
Selection Advantages by Application
Solar PV Mounting Systems
Partial-thread bolts help maintain defined grip length in rails, brackets and frame connections. Common RFQ models include M8 x 40, M10 x 50 and M12 x 60 stainless hex bolts. SS304 / A2 is practical for general outdoor PV structures; SS316 / A4 is preferred for coastal solar projects.
Renewable energy fastenersMarine & Coastal Hardware
SS316 / A4 is recommended where salt spray, chloride exposure or wet outdoor service is present. Typical marine RFQs include M10 x 50, M12 x 60 and M16 x 80 partial-thread stainless bolts; A4-80 can be specified when higher mechanical performance is required.
Marine fastenersConstruction & Outdoor Structures
SS304 / A2 suits stainless brackets, railings, facade attachments and exposed equipment frames in normal atmospheric service. M12 x 60, M16 x 80 and M20 x 100 are common starting points when the joint needs an unthreaded shank through the clamped parts.
Construction fastenersRailway & Rolling Stock Equipment
Useful for covers, brackets and maintenance-access joints where external hex drive access, stainless corrosion resistance and locking method selection are important. M8 x 40, M10 x 50 and M12 x 60 are often requested for bracket and access-panel assemblies.
Railway fastenersWater Treatment / Hygienic Equipment
SS316 / A4 and passivated finish are suitable for wet, washdown or hygienic equipment environments. Common RFQ sizes include M8 x 40, M10 x 50, M12 x 60 and M16 x 80; confirm cleanability, washer selection, crevice risk and certificate requirements before ordering.
Hygienic equipment fasteners03
Assembly
Recommended Matching Products
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Manufacturing
Manufacturing & Quality Control
Manufacturing CapabilityQuality Control
Cold forming or hot forging selected by size and quantityIncoming stainless material verification
CNC machining support for non-standard length or thread requirementsThread gauge inspection for metric thread fit
Passivation and stainless surface finishingDimensional inspection against drawing or standard
Standard, semi-standard and drawing-based productionTensile, hardness or salt-spray tests arranged when specified
Export packaging by project requirementCoC, MTC and inspection report prepared on request
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FAQ
Common Questions Before RFQ
What is the difference between DIN 931 and DIN 933?
DIN 931 refers to partial-thread hex head bolts, while DIN 933 refers to full-thread hex head bolts. Use DIN 931 / ISO 4014 when the joint requires a defined grip length or an unthreaded shank through the clamped area.
When should I choose partial thread instead of full thread?
Partial-thread bolts are commonly selected when thread exposure inside the grip area should be reduced or when the drawing specifies a defined shank length. Full-thread bolts are preferred when full-length thread engagement or adjustment range is required.
Should I choose SS304 or SS316?
SS304 / A2 is suitable for general corrosion-resistant indoor and outdoor assemblies. SS316 / A4 is preferred for marine, coastal, washdown, chemical or chloride-exposed environments.
Can these bolts be supplied in A4-80?
Yes. SS316 / A4-80 can be supplied for stainless partial-thread hex head bolts when higher stainless strength and improved chloride corrosion resistance are required.
What DIN 931 stainless bolt sizes are commonly requested?
Common RFQ models include M8, M10, M12, M16 and M20 partial-thread stainless hex bolts, with typical order examples such as M8 x 40, M10 x 50, M12 x 60, M16 x 80 and M20 x 100. Final length, thread length, grip length and certificate requirements should be confirmed by drawing or purchase specification.
Can you supply matching nuts and washers?
Yes. Matching stainless hex nuts, flat washers, spring washers, toothed lock washers or nylon insert lock nuts can be supplied as bolt-nut-washer sets.
Are MTC and EN 10204 3.1 certificates available?
Material certificates, CoC and dimensional inspection reports can be supplied according to project requirements. EN 10204 3.1 certificate requirements should be confirmed before production.
Need stainless hex head bolts for your project?
Send your drawing, standard, size, material, grade, quantity and certificate requirements. Our team can recommend the suitable material, surface finish, matching nuts and washers, then provide a project quotation.
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