RAYCHIN LIMITED, we are materials experts who focus only on fasteners made from the highest performance specialty metals for the most challenging and extreme applications.

• Stainless Steel Series: Martensitic Stainless Steel, Ferritic Stainless Steel, Austenitic Stainless Steel, Austenitic-Ferritic (Duplex) Stainless Steel and Precipitation Hardening Stainless Steel.

• Super Alloys Series: Nickel-based Alloy, Cobalt-based Alloy, Iron-based Alloy, Molybdenum-based Alloy, ‌Titanium-based Alloy, Copper based Alloy, ‌Zirconium Alloy.

• Alloy Steel Series: Low Alloy Steel, Medium Alloy Steel, High Alloy Steel, Special Alloy Steel.

Round Head Bolts | Dome Head & Button Head Fasteners in Special Alloys | RAYCHIN Manufacturer

RAYCHIN manufactures round head bolts in 25+ alloys including Titanium, Inconel & Hastelloy. DIN 603 button head screws, dome head bolts & custom round fasteners compliant with ASME, ISO, JIS standards. Global supplier for marine, chemical & food industries.

Round Head Bolts for Low-Profile, Aesthetic & Corrosion-Resistant Applications

RAYCHIN is a premier manufacturer of precision round head bolts (commonly called dome head bolts, button head screws, or mushroom head bolts)—fasteners featuring a smoothly contoured, hemispherical head that provides an attractive finish while minimizing snag hazards. These specialized bolts offer superior corrosion resistance in hard-to-clean applications and are essential in industries requiring hygienic design, aerodynamic profiles, and marine environments. We engineer these fasteners from over 25 advanced alloys to meet stringent requirements in marine, food processing, chemical, architectural, and transportation industries worldwide.

Round Head Bolt Types & Classifications

We manufacture comprehensive round head bolt configurations to address diverse application needs:

1. Standard Round Head Bolts:

• Round Head Square Neck Bolts (Coach Bolts): Feature a square section beneath the head that locks into wood or metal, preventing rotation during installation. Manufactured to DIN 603, ISO 7377, and ASME B18.5 standards.

• Round Head Rib Neck Bolts: Similar to square neck but with ribbed underside for enhanced anti-rotation in marine woodwork and structural applications.

• Button Head Socket Cap Screws: Low-profile internal drive (Allen/hex) round head screws compliant with DIN 7380, ISO 7380-1, and ASME B18.3 standards.

2. Special Application Round Head Bolts:

• Dome Head Bolts with Slotted/Phillips Drive: Traditional drive styles for architectural hardware and vintage restoration projects.

• Round Head Shoulder Bolts: Combine dome head with precision shoulder for pivoting applications in corrosive environments.

• Round Head Flange Bolts: Integrate flange beneath dome head for increased bearing surface.

• Custom Round Head Designs: Manufactured to exact OEM specifications with unique head profiles, drive types, and special finishes.

Material Grades & International Standard Specifications

Our round head bolts are precision-engineered from the following advanced material systems with full international standard compliance:

1. Precipitation-Hardening Stainless Steels:

• 17-4 PH (UNS S17400): Supplied to ASTM A564 Type 630, AMS 5643, DIN 1.4542 in H900, H1025, H1150 tempers for high-strength marine round head bolts.

• PH 13-8 Mo (UNS S13800): Manufactured per ASTM A564 Type 625, AMS 5629 for superior corrosion resistance.

2. Nickel-Based Superalloys:

• Inconel® Alloys: Inconel 718 (UNS N07718/AMS 5663), Inconel 625 (UNS N06625/ASTM B446), Inconel 600 (UNS N06600) for extreme temperature exhaust system bolts.

• Monel® Alloys: Monel K500 (UNS N05500/AMS 4676), Monel 400 (UNS N04400) for marine hardware and chemical processing bolts.

• Hastelloy® Alloys: Hastelloy C276 (UNS N10276/ASTM B574), C22 (UNS N06022), B2 (UNS N10665) for severe chemical environments.

• Waspaloy (UNS N07001): Per AMS 5708, AMS 5824 for high-temperature applications.

• Nimonic® Series: Nimonic 80A (UNS N07080), Nimonic 90 (UNS N07090) compliant with BS HR 501/502 standards.

3. Duplex & Super Duplex Stainless Steels:

• Duplex Steel: Duplex 2205 (UNS S32205) to ASTM A193 B8S, EN 1.4462 specifications for offshore round head bolts.

• Super Duplex Alloys: Alloy 926 (UNS N08926), AL-6XN® (UNS N08367) meeting ASTM A193 B8S, NACE MR0175.

4. Titanium Alloys:

• Grade 5 Titanium (Ti-6Al-4V): UNS R56400 per AMS 4928, ASTM F467 for lightweight aerospace dome head bolts.

• Grade 2 Titanium: UNS R50400 to ASTM B348, AMS 4921 for marine grade round head bolts.

5. Refractory & Exotic Metals:

• Tantalum (UNS R05200): ASTM B365, AMS 7845 for chemical reactor dome head bolts.

• Zirconium 702 (UNS R60702): ASTM B550, ASME SB550 for sulfuric acid applications.

• Molybdenum (UNS R03600) & Tungsten: For extreme temperature applications.

6. Specialty Alloys:

• Nitronic® Alloys: Nitronic 60 (UNS S21800), Nitronic 50 (UNS S20910) to ASTM A193 B8N for high-strength applications.

• High-Performance Stainless: 254 SMO (UNS S31254/EN 1.4547), 310SS (UNS S31000), Alloy 20 (UNS N08020), Alloy 330 (UNS N08330).

• Cobalt Alloys: MP35N (UNS R30035/AMS 5844), MP159 (AMS 5846) for ultra-high strength.

• Iron-Based Superalloy: A286 (UNS S66286) to AMS 5731, ASTM A453 Grade 660.

7. Aluminum Alloy:

• Aluminum 7075 (UNS A97075): AMS QQ-A-225/9, ASTM F467 in T6, T73 tempers for lightweight architectural round head bolts.

8. Pure Nickel & Incoloy:

• Nickel 200 (UNS N02200): ASTM B160, ASME SB160.

• Incoloy® Alloys: Incoloy 825 (UNS N08825), Incoloy 925 (UNS N09925).

Custom Round Head Bolt Manufacturing Services

RAYCHIN provides complete custom round head bolt manufacturing from your technical specifications:

• Standards Compliance: DIN 603, ISO 7377, ASME B18.5, JIS B1180, and customer drawings.

• Special Features: Anti-rotation squares/ribs, custom dome radii, special drives, thread-locking features, polished finishes.

• Surface Finishes: Mechanical polishing, electropolishing, passivation, special coatings.

• Full Processing: Hot/cold forging, CNC machining, thread rolling, heat treatment, surface finishing.

• Quality Assurance: Complete MTRs (EN 10204 3.1), salt spray testing, surface finish verification, compliance with FDA, 3-A Sanitary Standards, ISO 9001.

Industry Applications

• Marine & Shipbuilding: Deck hardware, hull fittings, marine railings (ABS, DNV, LR certified)

• Food & Beverage Processing: Equipment assembly, conveyor systems, sanitary fittings (3-A, FDA, EHEDG compliant)

• Chemical Processing: Tank covers, access panels, reactor lids

• Architectural & Construction: Decorative hardware, curtain walls, structural glazing

• Transportation: Rail interiors, aircraft interiors, luxury vehicle trim

• Pharmaceutical: Clean room equipment, processing machinery

Why Choose RAYCHIN?

• Material Expertise: 25+ years experience with corrosion-resistant round head bolts

• Surface Finish Specialization: Electropolishing and mirror finishing capabilities

• Industry Certifications: Products meet 3-A Sanitary, FDA, Marine Grade requirements

• Global Standards: Compliance with DIN, ISO, ASME, JIS, ASTM standards

• Design Support: CAD modeling and prototype development services

• Global Supply: Reliable supplier to North America, EU, Asia-Pacific, Middle East markets

Request Round Head Bolt Quotation
Contact RAYCHIN for engineering consultation and competitive pricing. Submit your drawings for dome head bolts, button head screws, or custom round head fasteners.

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