Selection Guide

The property class indicates tensile strength and yield ratio. Class 8.8 has 800 MPa tensile strength and 640 MPa yield; class 10.9 is 1000 MPa / 900 MPa. For heavy loads, vibration or safety-critical joints, class 10.9 and above is recommended.

316 contains molybdenum and resists chloride corrosion better, suiting coastal, chemical and marine environments. 304 is more economical for general outdoor and indoor use. Fasteners are commonly A2-70 (304) and A4-80 (316).

Electro-galvanizing offers good appearance and low cost for indoor use. Hot-dip galvanizing has a thick coating and long salt-spray life for outdoor structures. Dacromet has no hydrogen embrittlement risk and excellent corrosion resistance, suiting high-strength parts and harsh environments.

There is no absolute conversion; it depends on the environment. Neutral salt spray of 48–96h generally suits indoor use, 240h and above suits outdoor use, and 720h and above suits coastal or highly corrosive environments. Selection should also consider the environment category.

Common methods include spring washers, lock nuts, double nuts, thread adhesive, lock washers and preload control. In vibrating applications, combine methods and apply torque to specification.

Stainless steel threads are prone to cold welding and adhesive wear under load, leading to galling. Reduce torque, use thread lubricant, control assembly speed, or pair with a different material to avoid it.

Provide a drawing (with dimensions, tolerances, material, property class, surface finish and quantity) or a sample. First-article confirmation is recommended before volume production.

Standard export packing uses cartons, pallets and stretch film, with moisture-proof treatment on request. Lead time depends on specification and quantity: standard parts are usually 15–25 days; custom parts are confirmed separately.