What is the difference between fasteners made from Grade 8, A354, and 8.8?
It can seem confusing, so let’s see if we can clarify a little about the difference between fasteners made from Grade 8, A354, and 8.8. First and foremost, all of the above would be classified as high strength fasteners, but not all high strength fasteners are the same.
Let’s start with Metric Property Class 8.8, or as it is generally referred to as “Class 8.8”. This is a high strength standard associated exclusively with metric fasteners and would fall under the ISO 898-1 standard. It covers thread sizes M3 thru to M39.
Grade 8 is one of the most commonly referenced high strength fasteners and falls under the SAE J429 Standard. It covers parts with threads from 1/4” thru to 1-1/2”.
A354 Grade BD
A354 Grade BD is also a commonly referenced high strength fastener standard with almost identical chemical and mechanical properties to the Grade 8. The main difference between the two is that A354 Grade BD covers threads from 1/4” thru to 4” and has higher allowable Phosphorus and Sulfur contents.
Please see the table below for more details.