Stainless Steel Bolt Strength Grades And Types

Stainless steel bolts are one of the most commonly used fastening materials in construction and decoration. Due to their high demand and wide range of applications, it is essential for those preparing for renovation projects to have a thorough understanding of them. So, how are the strength grades of stainless steel bolts classified, and what types are available? Let's first take a look at the strength grades of stainless steel bolts!

1. Strength Grades of Stainless Steel Bolts
What is a Stainless Steel Bolt?
A stainless steel bolt is a highly resistant fastener that can withstand corrosion from acids, alkalis, and salts. Depending on its composition, its resistance properties may vary-some may resist rust but not acids. In daily life, commonly used stainless steel bolts include models such as 304 and 316.

Strength Grades
① The most common performance grade for stainless steel bolts is 8.8, which indicates a tensile strength of 800 MPa and a yield strength of 640 MPa. Stainless steel bolts can be classified into 10 grades based on performance, ranging from 3.6 to 12.9. The decimal here is not a mathematical point-the left digit represents the material's ultimate strength, while the right digit represents the ratio of yield strength to tensile strength.

② Nuts are divided into 7 grades, from 4 to 12, where a higher number indicates greater minimum stress tolerance.

③ Based on thread classification:

External threads are categorized as 1A, 2A, and 3A.

Internal threads are categorized as 1B, 2B, and 3B.
The higher the number, the tighter the fit:

1A/1B: Loose tolerance, suitable for general applications.

2A/2B: The most commonly used thread tolerance in imperial fasteners.

3A/3B: The tightest fit, primarily used in safety-critical designs.

④ Thread grades also differ between external and internal threads:

External threads: 4H, 6H, 6G

Internal threads: 5H, 6H, 7H
The best thread combinations for strong fastening are H/g, H/H, or G/H.

2. Types of Stainless Steel Bolts
Stainless steel bolts come in dozens of varieties, each designed for specific purposes. Common types include:

• Hexagon head bolts
• Hexagon socket set screws
• Button head socket cap screws
• Cross-recessed pan head self-tapping screws
• Hex nuts
• Wing nuts