What are the main materials and models of stainless steel fasteners?

Stainless steel fasteners are widely used in construction installation, machinery and equipment, power systems, automobile manufacturing, rail transportation, outdoor facilities, and new energy equipment. Due to their corrosion resistance, stable strength, clean appearance, and low maintenance costs, stainless steel has become an important choice for bolts, nuts, washers, screws, and other fasteners. Common products include Stainless Steel Screws, Hex Bolts, Pan Head Screws, Countersunk Flat Head Screws, etc.

 

Choosing the right stainless steel fasteners usually requires judging from two core dimensions: the material grade and the specifications and applicable standards. The following is a systematic explanation from an industry application perspective.
 

 

 

1. Austenitic Stainless Steel (Mainstream Type)

The austenitic series is the most widely used material in stainless steel fasteners, accounting for the mainstream market share. Its characteristics include excellent corrosion resistance, good plasticity, suitability for cold heading, and rust resistance.

 

304 Stainless Steel

304 is the most common general-purpose material, suitable for ordinary indoor and outdoor environments, balancing performance and cost. Commonly used in:
Furniture mounting parts
Equipment housing connectors
Architectural hardware
Machine screws with Phillips heads
Stainless steel pan head screws

The 304 series is also commonly used in assemblies, such as:
M10 304 Stainless Steel Hex Bolt Screw Nut Flat Washer Combination

316 Stainless Steel

316 adds molybdenum to 304, resulting in stronger resistance to salt spray and chloride ion corrosion, suitable for high humidity, high salt, and high corrosion environments. Commonly used in:
Seaside projects
Marine equipment
Food machinery
Medical equipment
Chemical equipment
302HQ / 304HC
These materials are mainly used in precision screw manufacturing, with excellent cold forming performance, suitable for small-size, high-precision products.

 

2. Martensitic Stainless Steel (High-Strength Type)
Martensitic materials can have their hardness and strength increased through heat treatment, suitable for environments subjected to mechanical loads or abrasion.

410 Stainless Steel
High strength, commonly used in:
Industrial machinery connectors
Automotive structural components
Stainless steel set screws
420 Stainless Steel
Hardness higher than 410, suitable for wear-resistant applications, such as locking components, positioning components, and high-strength fasteners.

 

3. Ferritic Stainless Steel (Economy Grade)
Representative grade: 430. Offers some corrosion resistance, lower cost than 304, suitable for general environments.
Common applications:
Applied appliance housings
Decorative parts
Interior structural components
Suitable for budget-sensitive projects, but not recommended for high-humidity or long-term outdoor exposure environments.

 

4. Duplex and Special Stainless Steel (High-End Applications)
2205 Duplex Steel
Combines high strength with excellent corrosion resistance, suitable for offshore platforms, energy equipment, and large-scale structural engineering.

17-4PH Precipitation Hardening Steel
Extremely high strength, widely used in aerospace, precision machinery, and special equipment connection systems.

 

 

 

Stainless steel fastener classifications are typically composed of product type, thread specification, length, head type, and standard.

 

1. Bolts
Used for structural fixing, equipment assembly, and load-bearing connections.

 

Common Types:
Hex Bolts
Flanged Hexagon Head Bolt Screw
Hexagon Head Machine Screw
Metric Thread
Flat Spring Lock
Washer Bolt
304 Stainless Steel

Common Specifications:
M6
M8
M10
M12
M16

Examples:
M10 Clamp Wire Terminal
M8 Socket Head Cap Screws Terminal with Spacer

 

2. Screws
Suitable for thin plates, equipment panels, electrical assemblies, and precision installation.

 

Common Products:

Pan Head Screw (Stainless Steel)

Countersunk Flat Head Screws

Flat-head Hexagon Socket (Stainless Steel Screws)

Machine Screw with Phillips Head

 

Application Notes:
Pan head screws are suitable for surface mounting.
Countersunk screws are suitable for applications requiring a flat surface.
Hexagon socket screws are suitable for high-torque installation.

 

3. Set Screws
Mainly used for shaft positioning, component locking, and mechanical transmission systems.

Typical Products:
Set Screw with Hollow Head Bolt Base

Stainless steel set screws

 

4. Self-Tapping Screws
No pre-installed nut required; can be directly screwed into wood, plastic, or thin steel sheets.

Common Categories: Stainless steel sheet metal screws, Stainless steel roofing screws, Stainless steel cladding screws, Stainless steel trim screws, Stainless tapcon. Suitable for: Roofing installation, Curtain wall fixing, Metal panel connection, Exterior wall system construction.

 

 

 

Metric Specifications: M indicates metric threads, for example: M6 × 20, M8 × 30, M10 × 50. Meaning: Thread diameter × Length (mm). Imperial Specifications: For example: 1/4-20 × 1". Commonly used in North American market equipment and export projects. Long Size Specifications: For example, 100mm stainless steel screws. Suitable for deep installation, thick plate connections, or special structural requirements.

 

Common Standards: Fastener production is usually based on the following standards: GB (Chinese National Standard), DIN (German Standard), ISO (International Standard), ANSI/ASME (American Standard System), JIS (Japanese Standard). Japanese Industrial Standards

Customers in different markets typically specify standard systems, which need to be confirmed during procurement.

 

 

Humid or Coastal Environments

Recommended Selection:
316 Stainless Steel
2205 Duplex Steel

General Industrial and Building Environments
Recommended Selection:
304 Stainless Steel
SS Screws

High-Strength Mechanical Scenarios

Recommended Selection:
410
420
17-4PH

Low-Cost Indoor Applications
Recommended Selection:
430 Stainless Steel

 

 

When selecting stainless steel fasteners, the following should be confirmed:

Material Grade
Thread Specification
Length Dimension
Head Type Structure
Strength Grade
Surface Condition
Standard Applicable Environment

For example, when purchasing M6 Hexagon Socket Head Screw 304 Stainless Steel Knurling, it should be confirmed whether knurling, anti-slip properties, torque requirements, and the size of matching tools are required.

 

 

The mainstream materials for stainless steel fasteners are 304, 316, 410, and 430, with 304 having the widest application range, followed by 316...

 

More suitable for corrosive environments, 410 offers higher strength, while 430 is suitable for cost-controlled projects. Models include Hex Bolts, steel screws, self-tapping screws, pan head screws, countersunk head screws, and various assemblies.

 

In actual selection, a comprehensive judgment should be made based on the usage environment, load requirements, installation method, and budget to obtain a more stable and economical connection solution.