Alloy Steel Grade 129 Precision Step Bolt Metric M16x50 Zinc Plating Black Shipbuilding
Alloy Steel Grade 129 Precision Step Bolt Metric M16x50 Zinc Plating Black Shipbuilding
1,Description:
Shoulder screws are also called shaft shoulder screws, stop screws, stop bolts, brake bolts, equal-height screws, etc. The plug screw is used in conjunction with the bolt pull rod and is mainly used as a mold accessory to control the opening stroke between the fixed mold seat plate, the runner push plate and the fixed mold template in the three-plate mold.
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Because it can be set on the parting surface of the mold, the mold design can be miniaturized. This type of product features high hardness, good toughness, excellent wear resistance and heat resistance. It is suitable for precision molds and can significantly extend their service life. Especially, the thermal deformation of precision molds has been effectively controlled, making it suitable for molds in high-temperature working environments.
Its standard is ISO 7379. The material of the 12.9 grade plug screw is SCM435 alloy steel, with an overall hardness of HRC40°.
2,Applications:
Grade 129 ultra-high strength alloy steel metric M16x50 precision step bolt is tailored for heavy-duty shipbuilding hull and deck assembly engineering, finished with industrial black zinc plating anti-corrosion coating to adapt to marine high-salinity humid corrosive environment all year round. Adopting Grade 129 chromium-molybdenum alloy steel raw material, the bolt is processed by secondary vacuum heat treatment, with far higher shear strength and impact resistance than grade 109 carbon steel fasteners, able to bear ocean wave impact load, hull telescoping stress and deck heavy equipment extrusion pressure during ship navigation. The dual-diameter precision step structure is polished by five-axis CNC finishing, with smooth step transition surface, no burr edge, accurate limit stroke, suitable for positioning and fastening of ship deck bulkhead, marine pipeline support, cabin heavy equipment base and hull reinforced connecting parts. Black zinc plating thickened protective layer resists seawater salt ion penetration, marine algae corrosive liquid and ocean wind sand abrasion, greatly reducing metal oxidation rust speed in offshore working areas. M16 large-diameter metric thread adopts reinforced tooth root design, effectively avoid tooth fracture under long-term heavy load, improve overall structural safety of ship bearing connection parts. All products comply with IMO marine fastener safety standards, pass 1000-hour marine salt spray inspection and heavy load fatigue cycle test. Compared with ordinary step bolts, this alloy steel model has better high-pressure bearing performance, will not deform or loosen when hull shakes violently, integrates positioning, limiting and fixed connection functions, reduces matching gasket use in ship assembly, simplifies on-site shipyard installation process, lowers later hull fastener replacement frequency, and is a core heavy-load anti-corrosion fastener for inland waterway ships and offshore engineering vessels.
3,Technical Advantages
Grade 129 Cr-Mo Alloy Steel chemical composition: 0.35% carbon, 1.1% chromium, 0.25% molybdenum, trace vanadium strengthening element, high density heavy-load alloy substrate. Material maintenance rules: Black marine zinc coating needs quarterly inspection on offshore sites; flush bolt surface with fresh water to remove seawater salt residue after voyage; supplement marine anti-corrosion grease on thread gaps; avoid impact scratch on step surface; replace bolts once coating peels over 10%, prohibit welding modification on alloy body to avoid material performance failure.
Available in small packing, carton packing, or pallet configurations to meet your shipping and storage requirements.
Manufactured by JIA SHAN Hardware Company with strict quality control measures and pre-shipment inspection.
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