Stainless steel - Hexagon bolt

Technical Characteristics of Stainless Hex Bolts

Hexagon bolts represent the industry standard for securing heavy machinery and structural components. The external hex drive allows for significant leverage, making them suitable for applications requiring substantial clamping force. When manufactured from stainless steel, these bolts offer a vital combination of mechanical strength and resistance to environmental degradation, eliminating the need for protective coatings that can flake or wear off.

Material Specifications and Properties

Choosing the right stainless steel grade is critical for ensuring the bolt can withstand both the physical load and the chemical environment. Our hex bolts are typically supplied in the cold-worked condition (Class 70) to ensure optimal tensile strength.

Steel Grade	AISI Standard	Performance in Hex Bolts	Tensile Strength
A2	304	Excellent for general atmospheric exposure. The standard choice for indoor and outdoor machinery where saltwater is not present.	Min. 700 N/mm²
A4	316	Required for marine and chemical environments. The molybdenum content prevents pitting corrosion on the bolt head and shank.	Min. 700 N/mm²

Quality Assurance and MTC

At Fastener Core, we prioritize transparency in material quality. We provide EN 10204 3.1 Material Test Certificates (MTC) free of charge upon request. These certificates validate the chemical composition and mechanical properties of the bolts supplied. While MTCs are complimentary, please note that any requests for third-party inspection services are subject to additional fees.

Key Industrial Applications

Stainless steel hex bolts are widely utilized across industries that demand hygiene and longevity:

• Water & Waste Management: Pump assembly and pipe flanges requiring resistance to moisture.
• Chemical Processing: Fastening tanks and vessels where chemical spill resistance is necessary.
• Food Industry: Conveyor systems and machinery where non-toxic, easy-to-clean fasteners are mandatory.
• Construction: Structural connections in outdoor architectural projects.

Frequently Asked Questions

What is the recommended tightening torque for stainless steel hex bolts?

Torque values depend heavily on the bolt diameter, the friction coefficient (lubrication), and the specific grade (A2/A4). Stainless steel has a higher coefficient of friction than carbon steel. It is critical to consult a specific torque chart for austenitic stainless steel to avoid over-tightening, which can lead to yield failure or thread galling.

Why do stainless steel bolts sometimes seize up during installation?

This phenomenon is known as "galling" or cold welding. It occurs when pressure and friction generate heat between the thread surfaces, causing them to fuse. To prevent this with hex bolts, ensure threads are clean, use a slow tightening speed (avoid high-speed impact drivers), and apply a suitable anti-seize lubricant.

How can I distinguish between A2 and A4 hex bolts?

Visually, they look identical. However, all our hex bolts are clearly head-marked for identification. You will see "A2-70" or "A4-70" stamped on the head of the bolt. "A2" indicates 304 grade, "A4" indicates 316 grade, and "70" indicates the strength class (700 N/mm² tensile strength).